January 20, 2010

-page 60-

Many paradoxes are an easy source of antinomies, for example, Zeno gave some famously lets say, logical-cum-mathematical arguments that might be interpreted as demonstrating that motion is impossible. But our eyes as it was, demonstrate motion (exhibit moving things) all the time. Where did Zeno go wrong? Where do our eyes go wrong? If we cannot readily answer at least one of these questions, then we are in antinomy. In the Critique of Pure Reason, Kant gave demonstrations of the same kind -in the Zeno example they were obviously not the same kind of both, e.g., that the world has a beginning in time and space, and that the world has no beginning in time or space. He argues that both demonstrations are at fault because they proceed on the basis of pure reason unconditioned by sense experience.


At this point, we display attributes to the theory of experience, as it is not possible to define in an illuminating way, however, we know what experiences are through acquaintances with some of our own, e.g., visual experiences of as afterimage, a feeling of physical nausea or a tactile experience of an abrasive surface (which might be caused by an actual surface -rough or smooth, or which might be part of a dream, or the product of a vivid sensory imagination). The essential feature of experience is it feels a certain way -that there is something that it is like to have it. We may refer to this feature of an experience as its character.

Another core feature of the sorts of experiences with which this may be of a concern, is that they have representational content. (Unless otherwise indicated, experience will be reserved for their contentual representations.) The most obvious cases of experiences with content are sense experiences of the kind normally involved in perception. We may describe such experiences by mentioning their sensory modalities ad their contents, e.g., a gustatory experience (modality) of chocolate ice cream (content), but do so more commonly by means of perceptual verbs combined with noun phrases specifying their contents, as in Macbeth saw a dagger. This is, however, ambiguous between the perceptual claim There was a (material) dagger in the world that Macbeth perceived visually and Macbeth had a visual experience of a dagger (the reading with which we are concerned, as it is afforded by our imagination, or perhaps, experiencing mentally hallucinogenic imagery).

As in the case of other mental states and events with content, it is important to distinguish between the properties that and experience represents and the properties that it possesses. To talk of the representational properties of an experience is to say something about its content, not to attribute those properties to the experience itself. Like every other experience, a visual; experience of a non-shaped square, of which is a mental event, and it is therefore not itself, or finds to some irregularity or is it square, even though it represents those properties. It is, perhaps, fleeting, pleasant or unusual, even though it does not represent those properties. An experience may represent a property that it possesses, and it may even do so in virtue of a rapidly changing (complex) experience representing something as changing rapidly. However, this is the exception and not the rule.

Which properties can be [directly] represented in sense experience is subject to debate. Traditionalists include only properties whose presence could not be doubted by a subject having appropriate experiences, e.g., colour and shape in the case of visual experience, and apparent shape, surface texture, hardness, etc., in the case of tactile experience. This view is natural to anyone who has an egocentric, Cartesian perspective in epistemology, and who wishes for pure data in experiences to serve as logically certain foundations for knowledge, especially to the immediate objects of perceptual awareness in or of sense-data, such categorized of colour patches and shapes, which are usually supposed distinct from surfaces of physical objectivity. Qualities of sense-data are supposed to be distinct from physical qualities because their perception is more relative to conditions, more certain, and more immediate, and because sense-data is private and cannot appear other than they are they are objects that change in our perceptual field when conditions of perception change. Physical objects remain constant.

Others who do not think that this wish can be satisfied, and who are more impressed with the role of experience in providing animisms with ecologically significant information about the world around them, claim that sense experiences represent properties, characteristic and kinds that are much richer and much more wide-ranging than the traditional sensory qualities. We do not see only colours and shapes, they tell us, but also earth, water, men, women and fire: We do not smell only odours, but also food and filth. There is no space here to examine the factors relevantly responsible to their choice of situational alternatives. Yet, this suggests that character and content are not really distinct, and there is a close tie between them. For one thing, the relative complexity of the character of sense experience places limitations upon its possible content, e.g., a tactile experience of something touching ones left ear is just too simple to carry the same amount of content as typically convincing to an every day, visual experience. Moreover, the content of a sense experience of a given character depends on the normal causes of appropriately similar experiences, e.g., the sort of gustatory experience that we have when eating chocolate would be not represented as chocolate unless it was normally caused by chocolate. Granting a contingent ties between the character of an experience and its possible causal origins, once, again follows that its possible content is limited by its character.

Character and content are none the less irreducibly different, for the following reasons. (1) There are experiences that completely lack content, e.g., certain bodily pleasures. (2) Not every aspect of the character of an experience with content is relevant to that content, e.g., the unpleasantness of an aural experience of chalk squeaking on a board may have no representational significance. (3) Experiences in different modalities may overlap in content without a parallel overlap in character, e.g., visual and tactile experiences of circularity feel completely different. (4) The content of an experience with a given character may vary according to the background of the subject, e.g., a certain content singing bird only after the subject has learned something about birds.

According to the act/object analysis of experience (which is a special case of the act/object analysis of consciousness), every experience involves an object of experience even if it has no material object. Two main lines of argument may be offered in support of this view, one phenomenological and the other semantic.

In an outline, or projective view, the phenomenological argument is as follows. Whenever we have an experience, even if nothing beyond the experience answers to it, we seem to be presented with something through the experience (which is itself diaphanous). The object of the experience is whatever is so presented to us-is that it is an individual thing, an event, or a state of affairs.

The semantic argument is that objects of experience are required in order to make sense of certain features of our talk about experience, including, in particular, the following. (1) Simple attributions of experience, e.g., Rod is experiencing an oddity that is not really square but in appearance it seems more than likely a square, this seems to be relational. (2) We appear to refer to objects of experience and to attribute properties to them, e.g., The after-image that John experienced was certainly odd. (3) We appear to quantify ov er objects of experience, e.g., Macbeth saw something that his wife did not see.

The act/object analysis comes to grips with several problems concerning the status of objects of experiences. Currently the most common view is that they are sense-data - private mental entities that actually posses the traditional sensory qualities represented by the experiences of which they are the objects. But the very idea of an essentially private entity is suspect. Moreover, since an experience may apparently represent something as having a determinable property, e.g., redness, without representing it as having any subordinate determinate property, e.g., any specific shade of red, a sense-datum may actually have a determinate property subordinate to it. Even more disturbing is that sense-data may have contradictory properties, since experiences can have contradictory contents. A case in point is the waterfall illusion: If you stare at a waterfall for a minute and then immediately fixate on a nearby rock, you are likely to have an experience of the rocks moving upward while it remains in the same place. The sense-data theorist must either deny that there are such experiences or admit contradictory objects.

These problems can be avoided by treating objects of experience as properties. This, however, fails to do justice to the appearances, for experience seems not to present us with properties embodied in individuals. The view that objects of experience is Meinongian objects accommodate this point. It is also attractive in as far as (1) it allows experiences to represent properties other than traditional sensory qualities, and (2) it allows for the identification of objects of experience and objects of perception in the case of experiences that constitute perception.

According to the act/object analysis of experience, every experience with content involves an object of experience to which the subject is related by an act of awareness (the event of experiencing that object). This is meant to apply not only to perceptions, which have material objects (whatever is perceived), but also to experiences like hallucinations and dream experiences, which do not. Such experiences none the less appear to represent something, and their objects are supposed to be whatever it is that they represent. Act/object theorists may differ on the nature of objects of experience, which have been treated as properties. Meinongian objects (which may not exist or have any form of being), and, more commonly private mental entities with sensory qualities. (The term sense-data is now usually applied to the latter, but has also been used as a general term for objects of sense experiences, as in the work of G.E. Moore) Act/object theorists may also differ on the relationship between objects of experience and objects of perception. In terms of perception (of which we are indirectly aware) are always distinct from objects of experience (of which we are directly aware). Meinongian, however, may treat objects of perception as existing objects of experience. But sense-datum theorists must either deny that there are such experiences or admit contradictory objects. Still, most philosophers will feel that the Meinongians acceptance of impossible objects is too high a price to pay for these benefits.

A general problem for the act/object analysis is that the question of whether two subjects are experiencing one and the same thing (as opposed to having exactly similar experiences) appears to have an answer only on the assumption that the experiences concerned are perceptions with material objects. But in terms of the act/object analysis the question must have an answer even when this condition is not satisfied. (The answer is always negative on the sense-datum theory; it could be positive on other versions of the act/object analysis, depending on the facts of the case.)

In view of the above problems, the case for the act/object analysis should be reassessed. The Phenomenological argument is not, on reflection, convincing, for it is easy enough to grant that any experience appears to present us with an object without accepting that it actually does. The semantic argument is more impressive, but is none the less answerable. The seemingly relational structure of attributions of experience is a challenge dealt with below in connection with the adverbial theory. Apparent reference to and quantification over objects of experience can be handled by analysing them as reference to experiences themselves and quantification over experiences tacitly typed according to content. Thus, The after-image that John experienced was colourfully appealing becomes Johns after-image experience was an experience of colour, and Macbeth saw something that his wife did not see becomes Macbeth had a visual experience that his wife did not have.

Pure cognitivism attempts to avoid the problems facing the act/object analysis by reducing experiences to cognitive events or associated disposition, e.g., Susys experience of a rough surface beneath her hand might be identified with the event of her acquiring the belief that there is a rough surface beneath her hand, or, if she does not acquire this belief, with a disposition to acquire it that has somehow been blocked.

This position has attractions. It does full justice to the cognitive contents of experience, and to the important role of experience as a source of belief acquisition. It would also help clear the way for a naturalistic theory of mind, since there seems to be some prospect of a physicalist/functionalist account of belief and other intentional states. But pure cognitivism is completely undermined by its failure to accommodate the fact that experiences have a felt character that cannot be reduced to their content, as aforementioned.

The adverbial theory is an attempt to undermine the act/object analysis by suggesting a semantic account of attributions of experience that does not require objects of experience. Unfortunately, the oddities of explicit adverbializations of such statements have driven off potential supporters of the theory. Furthermore, the theory remains largely undeveloped, and attempted refutations have traded on this. It may, however, be founded on sound basis intuitions, and there is reason to believe that an effective development of the theory (which is merely hinting at) is possible.

The relevant intuitions are (1) that when we say that someone is experiencing an A, or has an experience of an A, we are using this content-expression to specify the type of thing that the experience is especially apt to fit, (2) that doing this is a matter of saying something about the experience itself (and maybe about the normal causes of like experiences), and (3) that it is no-good of reasons to posit of its position to presuppose that of any involvements, is that its descriptions of an object in which the experience is. Thus the effective role of the content-expression in a statement of experience is to modify the verb it compliments, not to introduce a special type of object.

Perhaps, the most important criticism of the adverbial theory is the many property problem, according to which the theory does not have the resources to distinguish between, e.g.,

(1) Frank has an experience of a brown triangle

and:

(2) Frank has an experience of brown and an experience of a triangle.

Which is entailed by (1) but does not entail it. The act/object analysis can easily accommodate the difference between (1) and (2) by claiming that the truth of (1) requires a single object of experience that is both brown and triangular, while that of the (2) allows for the possibility of two objects of experience, one brown and the other triangular, however, (1) is equivalent to:

(1*) Frank has an experience of somethings being both brown and triangular.

And (2) is equivalent to:

(2*) Frank has an experience of somethings being brown and an experience of somethings being triangular,

and the difference between these can be explained quite simply in terms of logical scope without invoking objects of experience. The Adverbialists may use this to answer the many-property problem by arguing that the phrase a brown triangle in (1) does the same work as the clause somethings being both brown and triangular in (1*). This is perfectly compatible with the view that it also has the adverbial function of modifying the verb has an experience of, for it specifies the experience more narrowly just by giving a necessary condition for the satisfaction of the experience (the condition being that there are something both brown and triangular before Frank).

A final position that should be mentioned is the state theory, according to which a sense experience of an A is an occurrent, non-relational state of the kind that the subject would be in when perceiving an A. Suitably qualified, this claim is no doubt true, but its significance is subject to debate. Here it is enough to remark that the claim is compatible with both pure cognitivism and the adverbial theory, and that state theorists are probably best advised to adopt adverbials as a means of developing their intuitions.

Yet, clarifying sense-data, if taken literally, is that which is given by the senses. But in response to the question of what exactly is so given, sense-data theories posit private showings in the consciousness of the subject. In the case of vision this would be a kind of inner picture shown which it only indirectly represents aspects of the external world that has in and of itself a worldly representation. The view has been widely rejected as implying that we really only see extremely thin coloured pictures interposed between our minds eye and reality. Modern approaches to perception tend to reject any conception of the eye as a camera or lense, simply responsible for producing private images, and stress the active life of the subject in and of the world, as the determinant of experience.

Nevertheless, the argument from illusion is of itself the usually intended directive to establish that certain familiar facts about illusion disprove the theory of perception called naïevity or direct realism. There are, however, many different versions of the argument that must be distinguished carefully. Some of these distinctions centre on the content of the premises (the nature of the appeal to illusion); others centre on the interpretation of the conclusion (the kind of direct realism under attack). Let us set about by distinguishing the importantly different versions of direct realism which one might take to be vulnerable to familiar facts about the possibility of perceptual illusion.

A crude statement of direct realism might go as follows. In perception, we sometimes directly perceive physical objects and their properties, we do not always perceive physical objects by perceiving something else, e.g., a sense-datum. There are, however, difficulties with this formulation of the view, as for one thing a great many philosophers who are not direct realists would admit that it is a mistake to describe people as actually perceiving something other than a physical object. In particular, such philosophers might admit, we should never say that we perceive sense-data. To talk that way would be to suppose that we should model our understanding of our relationship to sense-data on our understanding of the ordinary use of perceptual verbs as they describe our relation to and of the physical world, and that is the last thing paradigm sense-datum theorists should want. At least, many of the philosophers who objected to direct realism would prefer to express in what they were of objecting too in terms of a technical (and philosophically controversial) concept such as acquaintance. Using such a notion, we could define direct realism this way: In veridical experience we are directly acquainted with parts, e.g., surfaces, or constituents of physical objects. A less cautious venison of the view might drop the reference to veridical experience and claim simply that in all experience we are directly acquainted with parts or constituents of physical objects. The expressions knowledge by acquaintance and knowledge by description, and the distinction they mark between knowing things and knowing about things, are generally associated with Bertrand Russell (1872-1970), that scientific philosophy required analysing many objects of belief as logical constructions or logical fictions, and the programme of analysis that this inaugurated dominated the subsequent philosophy of logical atomism, and then of other philosophers, Russells The Analysis of Mind, the mind itself is treated in a fashion reminiscent of Hume, as no more than the collection of neutral perceptions or sense-data that make up the flux of conscious experience, and that looked at another way that also was to make up the external world (neutral monism), but An Inquiry into Meaning and Truth (1940) represents a more empirical approach to the problem. Yet, philosophers have perennially investigated this and related distinctions using varying terminology.

Distinction in our ways of knowing things, highlighted by Russell and forming a central element in his philosophy after the discovery of the theory of definite descriptions. A thing is known by acquaintance when there is direct experience of it. It is known by description if it can only be described as a thing with such-and-such properties. In everyday parlance, I might know my spouse and children by acquaintance, but know someone as the first person born at sea only by description. However, for a variety of reasons Russell shrinks the area of things that can be known by acquaintance until eventually only current experience, perhaps my own self, and certain universals or meanings qualify anything else is known only as the thing that has such-and-such qualities.

Because one can interpret the relation of acquaintance or awareness as one that is not epistemic, i.e., not a kind of propositional knowledge, it is important to distinguish the above aforementioned views read as ontological theses from a view one might call epistemological direct realism? In perception we are, on at least some occasions, non-inferentially justified in believing a proposition asserting the existence of a physical object. Since it is that these objects exist independently of any mind that might perceive them, and so it thereby rules out all forms of idealism and phenomenalism, which hold that there are no such independently existing objects. Its being to direct realism rules out those views defended under the cubic of critical naive realism, or representational realism, in which there is some non-physical intermediary -usually called a sense-datum or a sense impression -that must first be perceived or experienced in order to perceive the object that exists independently of this perception. Often the distinction between direct realism and other theories of perception is explained more fully in terms of what is immediately perceived, than mediately perceived. What relevance does illusion have for these two forms of direct realism?

The fundamental premise of the arguments is from illusion seems to be the theses that things can appear to be other than they are. Thus, for example, straight sticks when immerged in water looks bent, a penny when viewed from certain perspective appears as an illusory spatial elliptic circularity, when something that is yellow when place under red fluorescent light looks red. In all of these cases, one version of the argument goes, it is implausible to maintain that what we are directly acquainted with is the real nature of the object in question. Indeed, it is hard to see how we can be said to be aware of the really physical object at all. In the above illusions the things we were aware of actually were bent, elliptical and red, respectively. But, by hypothesis, the really physical objects lacked these properties. Thus, we were not aware of the substantial reality of been real as a physical objects or theory.

So far, if the argument is relevant to any of the direct realises distinguished above, it seems relevant only to the claim that in all sense experience we are directly acquainted with parts or constituents of physical objects. After all, even if in illusion we are not acquainted with physical objects, but their surfaces, or their constituents, why should we conclude anything about the hidden nature of our relations to the physical world in veridical experience?

We are supposed to discover the answer to this question by noticing the similarities between illusory experience and veridical experience and by reflecting on what makes illusion possible at all. Illusion can occur because the nature of the illusory experience is determined, not just by the nature of events or sorted, conflicting affairs but the object perceived as itself the event in cause, but also by other conditions, both external and internal as becoming of an inner or as the outer experience. But all of our sensations are subject to these causal influences and it would be gratuitous and arbitrary to select from indefinitely of many and subtly different perceptual experiences some special ones those that get us in touch with the real nature of the physical world and its surrounding surfaces. Red fluorescent light affects the way things look, but so does sunlight. Water reflects light, but so does air. We have no unmediated access to the external world.

The Philosophy of science, and scientific epistemology are not the only area where philosophers have lately urged the relevance of neuroscientific discoveries. Kathleen Akins argues that a traditional view of the senses underlies the variety of sophisticated naturalistic programs about intentionality. Current neuroscientific understanding of the mechanisms and coding strategies implemented by sensory receptors shows that this traditional view is mistaken. The traditional view holds that sensory systems are veridical in at least three ways. (1) Each signal in the system correlates along with diminutive ranging properties in the external (to the body) environment. (2) The structure in the relevant relations between the external properties the receptors are sensitive to is preserved in the structure of the relations between the resulting sensory states, and (3) the sensory system theory, is not properly a single theory, but any approach to a complicated or complex structure that abstract away from the particular physical, chemical or biological nature of its components and simply considers the structure they together administer the terms of the functional role of individual parts and their contribution to the functioning of the whole, without fabricated additions or embellishments, that this is an external event. Using recent neurobiological discoveries about response properties of thermal receptors in the skin as an illustration, are, here, conversely acceptable of sensory systems from which are narcissistic than veridical. All three traditional assumptions are violated. These neurobiological details and their philosophical implications open novel questions for the philosophy of perception and for the appropriate foundations for naturalistic projects about intentionality. Armed with the known neurophysiology of sensory receptors, for example, our philosophy of perception or of perceptual intentionality will no longer focus on the search for correlations between states of sensory systems and veridically detected external properties. This traditionally philosophical (and scientific) project rests upon a mistaken veridical view of the senses. Neurophysiological constructs allow for the knowledge of sensory receptors to actively show that sensory experience does not serve the naturalist as well as a simple paradigm case of intentional relations between representation and the world. Once again, available scientific detail shows the naivety of some traditional philosophical projects.

Focusing on the anatomy and physiology of the pain transmission system, Valerie Hardcastle (1997) urges a similar negative implication for a popular methodological assumption. Pain experiences have long been philosophers favorite cases for analysis and theorizing about conscious experience generally. Nevertheless, every position about pain experiences has been defended recently: eliminativist, a variety of objectivists view, relational views, and subjectivist views. Why so little agreement, despite agreement that pain experience is the place to start an analysis or theory of consciousness? Hardcastle urges two answers. First, philosophers tend to be uninformed about the neuronal complexity of our pain transmission systems, and build their analyses or theories on the outcome of a single component of a multi-component system. Second, even those who understand some of the underlying neurobiology of pain tends to advocate gate-control theories. But the best existing gate-control theories are vague about the neural mechanisms of the gates. Hardcastle instead proposes a dissociable dual system of pain transmission, consisting of a pain sensory system closely analogous in its neurobiological implementation to other sensory systems, and a descending pain inhibitory system. She argues that this dual system is consistent with recent neuroscientific discoveries and accounts for all the pain phenomena that have tempted philosophers toward particular (but limited) theories of pain experience. The neurobiological uniqueness of the pain inhibitory system, contrasted with the mechanisms of other sensory modalities, renders pain processing atypical. In particular, the pain inhibitory system dissociates pains sensation from stimulation of nociceptors (pain receptors). Hardcastle concludes from the neurobiological uniqueness of pain transmission that pain experiences are atypical conscious events, and hence not a good place to start theorizing about or analyzing the general type.

Developing and defending theories of content is a central topic in current philosophy of mind. A common desideratum in this debate is a theory of cognitive representation consistent with a physical or naturalistic ontology. Here, described are a few contributions neuro philosophers have made to this literature.

When one perceives or remembers that he is out of coffee, his brain state possesses intentionality or aboutness. The percept or memory is about ones being out of coffee, and it represents one for being out of coffee. The representational state has content. Some psychosemantics seek to explain what it is for a representational state to be about something: to provide an account of how states and events can have specific representational content. Some physicalist psychosemantics seek to do this using resources of the physical sciences exclusively. Neuro-philosophers have contributed to two types of physicalist psychosemantics: the Functional Role approach and the Informational approach.

The nucleus of functional roles of semantics holds that a representation has its content in virtue of relations it bears to other representations. Its paradigm application is to concepts of truth-functional logic, like the conjunctive and disjunctive or, a physical event instantiates the function as justly the case that it maps two true inputs onto a single true output. Thus an expression bears the relations to others that give it the semantic content of and, proponents of functional role semantics propose similar analyses for the content of all representations (Form 1986). A physical event represents birds, for example, if it bears the right relations to events representing feathers and others representing beaks. By contrast, informational semantics associates content to a state depending upon the causal relations obtaining between the state and the object it represents. A physical state represents birds, for example, just in case an appropriate causal relation obtains between it and birds. At the heart of informational semantics is a causal account of information. Red spots on a face carry the information that one has measles because the red spots are caused by the measles virus. A common criticism of informational semantics holds that mere causal covariation is insufficient for representation, since information (in the causal sense) is by definition, always veridical while representations can misrepresent. A popular solution to this challenge invokes a teleological analysis of function. A brain state represents X by virtue of having the function of carrying information about being caused by X (Dretske 1988). These two approaches do not exhaust the popular options for some psychosemantics, but are the ones to which neuro philosophers have contributed.

Jerry Fodor and Ernest LePore raise an important challenge to Churchlands psychosemantics. Location in a state space alone seems insufficient to fix representational states endorsed by content. Churchland never explains why a point in a three-dimensional state space represents the Collor, as opposed to any other quality, object, or event that varies along three dimensions. Churchlands account achieves its explanatory power by the interpretation imposed on the dimensions. Fodor and LePore allege that Churchland never specifies how a dimension comes to represent, e.g., degree of saltiness, as opposed to yellow-blue wavelength opposition. One obvious answer appeals to the stimuli that form the external inputs to the neural network in question. Then, for example, the individuating conditions on neural representations of colours are that opponent processing neurons receive input from a specific class of photoreceptors. The latter in turn have electromagnetic radiation (of a specific portion of the visible spectrum) as their activating stimuli. Nonetheless, this appeal to exterior impulsions as the ultimate stimulus that included individual conditions for representational content and context, for which makes the resulting approaches of an interpretation implied by the versional information to semantics. If, not only, from which this approach is accordantly supported with other neurobiological inferences.

The neurobiological paradigm for informational semantics is the feature detector: One or more neurons that are (I) maximally responsive to a particular type of stimulus, and (ii) have the function of indicating the presence of that stimulus type. Examples of such stimulus-types for visual feature detectors include high-contrast edges, motion direction, and colours. A favorite feature detector among philosophers is the alleged fly detector in the frog. Lettvin et al. (1959) identified cells in the frog retina that responded maximally to small shapes moving across the visual field. The idea that this cell’s activity functioned to detect flies rested upon knowledge of the frogs’ diet. Using experimental techniques ranging from single-cell recording to sophisticated functional imaging, neuroscientists have recently discovered a host of neurons that are maximally responsive to a variety of stimuli. However, establishing condition (ii) on a feature detector is much more difficult. Even some paradigm examples have been called into question. David Hubel and Torsten Wiesels (1962) Nobel Prize adherents, who strove to establish the receptive fields of neurons in striate cortices were often interpreted as revealing cells manouevre with those that function continued of their detection, however, Lehky and Sejnowski (1988) have challenged this interpretation. They trained an artificial neural network to distinguish the three-dimensional shape and orientation of an object from its two-dimensional shading pattern. Their network incorporates many features of visual neurophysiology. Nodes in the trained network turned out to be maximally responsive to edge contrasts, but did not appear to have the function of edge detection.

Kathleen Akins (1996) offers a different neuro philosophical challenge to informational semantics and its affiliated feature-detection view of sensory representation. We saw in the previous section how Akins argues that the physiology of thermoreceptor violates three necessary conditions on veridical representation. From this fact she draws doubts about looking for feature detecting neurons to ground some psychosemantics generally, including thought contents. Human thoughts about flies, for example, are sensitive to numerical distinctions between particular flies and the particular locations they can occupy. But the ends of frog nutrition are well served without a representational system sensitive to such ontological refinements. Whether a fly seen now is numerically identical to one seen a moment ago, need not, and perhaps cannot, figure into the frogs feature detection repertoire. Akins critique casts doubt on whether details of sensory transduction will scale up to encompass of some adequately unified psychosemantics. It also raises new questions for human intentionality. How do we get from activity patterns in narcissistic sensory receptors, keyed not to objective environmental features but rather only to effects of the stimuli on the patch of tissue innervated, to the human ontology replete with enduring objects with stable configurations of properties and relations, types and their tokens (as the fly-thought example presented above reveals), and the rest? And how did the development of a stable, and rich ontology confer survival advantages to human ancestors?

Consciousness has reemerged as a topic in philosophy of mind and the cognition and attitudinal values over the past three decades. Instead of ignoring it, many physicalists now seek to explain it (Dennett, 1991). Here we focus exclusively on ways those neuroscientific discoveries have impacted philosophical debates about the nature of consciousness and its relation to physical mechanisms. Thomas Nagel (1937—), argues that conscious experience is subjective, and thus permanently recalcitrant to objective scientific understanding. He invites us to ponder what it is like to be a bat and urges the intuition that no amount of physical-scientific knowledge (including neuroscientific) supplies a complete answer. Nagels work is centrally concerned with the nature of moral motivation and the possibility of as rational theory of moral and political commitment, and has been a major impetus of interests in realistic and Kantian approaches to these issues. The modern philosophy of mind has been his ‘What is it Like to Be a Bat? , Arguing that there is an irreducible subjective aspect of experience that cannot be grasped by the objective methods of natural science, or by philosophies such as functionalism that confine themselves to those methods, as the intuition pump up has generated extensive philosophical discussion. At least two well-known replies make direct appeal to neurophysiology. John Biro suggests that part of the intuition pumped by Nagel, that bat experience is substantially different from human experience, presupposes systematic relations between physiology and phenomenology. Kathleen Akins (1993) delves deeper into existing knowledge of bat physiology and reports much that is pertinent to Nagels question. She argues that many of the questions about subjectivity that we still consider open hinge on questions that remain unanswered about neuroscientific details.

The more recent philosopher David Chalmers (1996), has argued that any possible brain-process account of consciousness will leave open an explanatory gap between the brain process and properties of the conscious experience. This is because no brain-process theory can answer the hard question: Why should that particular brain process give rise to conscious experience? We can always imagine (conceive of) a universe populated by creatures having those brain processes but completely lacking conscious experience. A theory of consciousness requires an explanation of how and why some brain process causes consciousness replete with all the features we commonly experience. The fact that the more difficult of questions remains unanswered implicates that we will probably never get to culminate of an explanation of consciousness, in that, at the level of neural compliance. Paul and Patricia Churchland have recently offered the following diagnosis and reply. Chalmers offer a conceptual argument, based on our ability to imagine creatures possessing brains like ours but wholly lacking in conscious experience. But the more one learns about how the brain produces conscious experience-and literature is beginning to emerge (e.g., Gazzaniga, 1995) - the harder it becomes to imagine a universe consisting of creatures with brain processes like ours but lacking consciousness. This is not just to bare assertions. The Churchlands appeal to some neurobiological detail. For example, Paul Churchland (1995) develops a neuroscientific account of consciousness based on recurrent connections between thalamic nuclei (particularly diffusely projecting nuclei like the intralaminar nuclei) and the cortex. Churchland argues that the thalamocortical recurrency accounts for the selective features of consciousness, for the effects of short-term memory on conscious experience, for vivid dreaming during REM. (rapid-eye movement) sleep, and other core features of conscious experience. In other words, the Churchlands are claiming that when one learns about activity patterns in these recurrent circuits, one can’t imagine or conceive of this activity occurring without these core features of conscious experience. (Other than just mouthing the words, I am now imagining activity in these circuits without selective attention/the effects of short-term memory/vivid dreaming . . . )

A second focus of sceptical arguments about a complete neuroscientific explanation of consciousness is sensory qualia: the introspectable qualitative aspects of sensory experience, the features by which subjects discern similarities and differences among their experiences. The colours of visual sensations are a philosopher’s favorite example. One famous puzzle about colour qualia is the alleged conceivability of spectral inversions. Many philosophers claim that it is conceptually possible (if perhaps physically impossible) for two humans not to diverge apart of similarities, but such are the compatibles as forwarded by their differing enation to neurophysiology. While the colour that fires engines and tomatoes appear to have of only one subject, is the colour that grasses and frogs appear in having the other (and vice versa). A large amount of neuroscientifically-informed philosophy has addressed this question. A related area where neurophilosophical considerations have emerged concerns the metaphysics of colours themselves (rather than Collor experiences). A longstanding philosophical dispute is whether colours are objective properties Existing external to perceiver or rather identifiable as or dependent upon minds or nervous systems. Some recent work on this problem begins with characteristics of Collor experiences: For example that Collor similarity judgments produce Collor orderings that align on a circle. With this resource, one can seek mappings of phenomenology onto environmental or physiological regularities. Identifying colours with particular frequencies of electromagnetic radiation does not preserve the structure of the hue circle, whereas identifying colours with activity in opponent processing neurons does. Such a tidbit is not decisive for the Collor objectivist-subjectivist debate, but it does convey the type of neurophilosophical work being done on traditional metaphysical issues beyond the philosophy of mind.

We saw in the discussion of Hardcastle (1997) two sections above that Neurophilosophers have entered disputes about the nature and methodological import of pain experiences. Two decades earlier, Dan Dennett (1978) took up the question of whether it is possible to build a computer that feels pain. He compares and notes the strong move between neurophysiological discoveries and common sense intuitions about pain experience. He suspects that the incommensurability between scientific and common sense views is due to incoherence in the latter. His attitude is wait-and-see. But foreshadowing Churchlands reply to Chalmers, Dennett favours scientific investigations over conceivability-based philosophical arguments.

Neurological deficits have attracted philosophical interest. For thirty years philosophers have found implications for the unity of the self in experiments with commissurotomy patients. In carefully controlled experiments, commissurotomy patients display two dissociable seats of consciousness. Patricia Churchland scouts philosophical implications of a variety of neurological deficits. One deficit is blindsight. Some patients with lesions to primary visual cortex report being unable to see items in regions of their visual fields, yet perform far better than chance in forced guess trials about stimuli in those regions. A variety of scientific and philosophical interpretations have been offered. Ned Form (1988) worries that many of these conflate distinct notions of consciousness. He labels these notions phenomenal consciousness (P-consciousness) and access consciousness (A-consciousness). The former is that which, what it is like-ness of experience. The latter are the availability of representational content to self-initiated action and speech. Form argues that P-consciousness is not always representational whereas A-consciousness is. Dennett and Michael Tye are sceptical of non-representational analyses of consciousness in general. They provide accounts of blindsight that do not depend on Forms distinction.

Many other topics are worth neurophilosophical pursuit. We mentioned commissurotomy and the unity of consciousness and the self, which continues to generate discussion. Qualia beyond those of Collor and pain have begun to attract neurophilosophical attention has self-consciousness. The first issues to arise in the philosophy of neuroscience (before there was a recognized area) were the localization of cognitive functions to specific neural regions. Although the localization approach had dubious origins in the phrenology of Gall and Spurzheim, and was challenged severely by Flourens throughout the early nineteenth century, it reemerged in the study of aphasia by Bouillaud, Auburtin, Broca, and Wernicke. These neurologists made careful studies (where possible) of linguistic deficits in their aphasic patients followed by brain autopsys postmortem. Brocas initial study of twenty-two patients in the mid-nineteenth century confirmed that damage to the left cortical hemisphere was predominant, and that damage to the second and third frontal convolutions was necessary to produce speech production deficits. Although the anatomical coordinates Brocas postulates for the speech production centres do not correlate exactly with damage producing production deficits as both are in this area of frontal cortexes and speech production requires of some greater degree of composure, in at least, that still bears his name (Brocas area and Brocas aphasia). Less than two decades later Carl Wernicke published evidence for a second language Centre. This area is anatomically distinct from Brocas area, and damage to it produced a very different set of aphasic symptoms. The cortical area that still bears his name (Wernickes area) is located around the first and second convolutions in temporal cortex, and the aphasia that bear his name (Wernickes aphasia) involves deficits in language comprehension. Wernickes method, like Brocas, was based on lesion studies: a careful evaluation of the behavioural deficits followed by post mortem examination to find the sites of tissue damage and atrophy. Lesion studies suggesting more precise localization of specific linguistic functions remain the groundwork of a strengthening foundation to which supports all while it remains in tack to this day in unarticulated research

Lesion studies have also produced evidence for the localization of other cognitive functions: for example, sensory processing and certain types of learning and memory. However, localization arguments for these other functions invariably include studies using animal models. With an animal model, one can perform careful behavioural measures in highly controlled settings, then ablate specific areas of neural tissue (or use a variety of other techniques to Form or enhance activity in these areas) and remeasure performance on the same behavioural tests. But since we lack an animal model for (human) language production and comprehension, this additional evidence isn’ available to the neurologist or neurolinguist. This fact makes the study of language a paradigm case for evaluating the logic of the lesion/deficit method of inferring functional localization. Philosopher Barbara Von Eckardt (1978) attempts to make explicitly the steps of reasoning involved in this common and historically important method. Her analysis begins with Robert Cummins early analysis of functional explanation, but she extends it into a notion of structurally adequate functional analysis. These analyses break down a complex capacity C into its constituent capacities 1, c2, . . . cn, where the constituent capacities are consistent with the underlying structural details of the system. For example, human speech production (complex capacity C) results from formulating a speech intention, then selecting appropriate linguistic representations to capture the content of the speech intention, then formulating the motor commands to produce the appropriate sounds, then communicating these motor commands to the appropriate motor pathways (constituent capacities c1, c2, . . . , cn). A functional-localization hypothesis has the form: Brain structure S in an organism (type) O has constituent capacity ci, where ci is a function of some part of O. An example, Brains Brocas area (S) in humans (O) formulates motor commands to produce the appropriate sounds (one of the constituent capacities ci). Such hypotheses specify aspects of the structural realization of a functional-component model. They are part of the theory of the neural realization of the functional model.

Armed with these characterizations, Von Eckardt argues that inference to some functional-localization hypothesis proceeds in two steps. First, a functional deficit in a patient is hypothesized based on the abnormal behaviour the patient exhibits. Second, localization of function in normal brains is inferred on the basis of the functional deficit hypothesis plus the evidence about the site of brain damage. The structurally-adequate functional analysis of the capacity connects the pathological behaviour to the hypothesized functional deficit. This connection suggests four adequacy conditions on a functional deficit hypothesis. First, the pathological behaviour P (e.g., the speech deficits characteristic of Brocas aphasia) must result from failing to exercise some complex capacity C (human speech production). Second, there must be a structurally-adequate functional analysis of how people exercise capacity C that involves some constituent capacity ci (formulating motor commands to produce the appropriate sounds). Third, the operation of the steps described by the structurally-adequate functional analysis minus the operation of the component performing ci (Brocas area) must result in pathological behaviour P. Fourth, there must not be a better available explanation for why the patient does P. Arguments to a functional deficit hypothesis on the basis of pathological behaviour is thus an instance of argument to the best available explanation. When postulating a deficit in a normal functional component provides the best available explanation of the pathological data, we are justified in drawing the inference.

Von Eckardt applies this analysis to a neurological case study involving a controversial reinterpretation of agnosia. Her philosophical explication of this important neurological method reveals that most challenges to localization arguments of whether to argue only against the localization of a particular type of functional capacity or against generalizing from localization of function in one individual to all normal individuals. (She presents examples of each from the neurological literature.) Such challenges do not impugn the validity of standard arguments for functional localization from deficits. It does not follow that such arguments are unproblematic. But they face difficult factual and methodological problems, not logical ones. Furthermore, the analysis of these arguments as involving a type of functional analysis and inference to the best available explanation carries an important implication for the biological study of cognitive function. Functional analyses require functional theories, and structurally adequate functional analyses require checks imposed by the lower level sciences investigating the underlying physical mechanisms. Arguments to best available explanation are often hampered by a lack of theoretical imagination: the available explanations are often severely limited. We must seek theoretical inspiration from any level of theory and explanation. Hence making explicitly the logic of this common and historically important form of neurological explanation reveals the necessity of joint participation from all scientific levels, from cognitive psychology down to molecular neuroscience. Von Eckardt anticipated what came to be heralded as the co-evolutionary research methodology, which remains a centerpiece of neurophilosophy to the present day.

Over the last two decades, evidence for localization of cognitive function has come increasingly from a new source: the development and refinement of neuroimaging techniques. The form of localization-of-function argument appears not to have changed from that employing lesion studies (as analysed by Von Eckardt). Instead, these imaging technologies resolve some of the methodological problems that plage lesion studies. For example, researchers do not need to wait until the patient dies, and in the meantime probably acquires additional brain damage, to find the lesion sites. Two functional imaging techniques are prominent: Positron emission tomography, or PET, and functional magnetic resonance imaging, or MRI. Although these measure different biological markers of functional activity, both now have a resolution down too around one millimetre. As these techniques increase spatial and temporal resolution of functional markers and continue to be used with sophisticated behavioural methodologies, the possibility of localizing specific psychological functions to increasingly specific neural regions continues to grow



What we now know about the cellular and molecular mechanisms of neural conductance and transmission is spectacular. The same evaluation holds for all levels of explanation and theory about the mind/brain: maps, networks, systems, and behaviour. This is a natural outcome of increasing scientific specialization. We develop the technology, the experimental techniques, and the theoretical frameworks within specific disciplines to push forward our understanding. Still, a crucial aspect of the total picture gets neglected: the relationships between the levels, the glue that binds knowledge of neuron activity to subcellular and molecular mechanisms, network activity patterns to the activity of and connectivity between single neurons, and behavioural network activity. This problem is especially glaring when we focus on the relationship between cognitivist psychological theories, postulating information-bearing representations and processes operating over their contents, and the activity patterns in networks of neurons. Co-evolution between explanatory levels still seems more like a distant dream rather than an operative methodology.

It is here that some neuroscientists appeal to computational methods. If we examine the way that computational models function in more developed sciences (like physics), we find the resources of dynamical systems constantly employed. Global effects (such as large-scale meteorological patterns) are explained in terms of the interaction of local lower-level physical phenomena, but only by dynamical, nonlinear, and often chaotic sequences and combinations. Addressing the interlocking levels of theory and explanation in the mind/brain using computational resources that have worked to bridge levels in more mature sciences might yield comparable results. This methodology is necessarily interdisciplinary, drawing on resources and researchers from a variety of levels, including higher levels like experimental psychology, program-writing and connectionist artificial intelligence, and philosophy of science.

However, the use of computational methods in neuroscience is not new. Hodgkin, Huxley, and Katz incorporated values of voltage-dependent potassium conductance they had measured experimentally in the squid giant axon into an equation from physics describing the time evolution of a first-order kinetic process. This equation enabled them to calculate best-fit curves for modelled conductance versus time data that reproduced the S-shaped (sigmoidal) function suggested by their experimental data. Using equations borrowed from physics, Rall (1959) developed the cable model of dendrites. This theory provided an account of how the various inputs from across the dendritic tree interact temporally and spatially to determine the input-output properties of single neurons. It remains influential today, and has been incorporated into the genesis software for programming neurally realistic networks. More recently, David Sparks and his colleagues have shown that a vector-averaging model of activity in neurons of correctly predicts experimental results about the amplitude and direction of saccadic eye movements. Working with a more sophisticated mathematical model, Apostolos Georgopoulos and his colleagues have predicted direction and amplitude of hand and arm movements based on averaged activity of 224 cells in motor cortices. Their predictions have borne out under a variety of experimental tests. We mention these particular studies only because we are familiar with them. We could multiply examples of the fruitful interaction of computational and experimental methods in neuroscience easily by one-hundred-fold. Many of these extend back before computational neuroscience was a recognized research endeavour.

We’ve already seen one example, the vector transformation accounts, of neural representation and computation, under active development in cognitive neuroscience. Other approaches using cognitivist resources are also being pursued. Many of these projects draw upon cognitivist characterizations of the phenomena to be explained. Many exploit cognitivist experimental techniques and methodologies, but, yet, some even attempt to derive cognitivist explanations from cell-biological processes (e.g., Hawkins and Kandel 1984). As Stephen Kosslyn puts it, cognitive neuroscientists employ the information processing view of the mind characteristic of cognitivism without trying to separate it from theories of brain mechanisms. Such an endeavour calls for an interdisciplinary community willing to communicate the relevant portions of the mountain of detail gathered in individual disciplines with interested nonspecialists: not just people willing to confer with those working at related levels, but researchers trained in the methods and factual details of a variety of levels. This is a daunting requirement, but it does offer some hope for philosophers wishing to contribute to future neuroscience. Thinkers trained in both the synoptic vision afforded by philosophy and the factual and experimental basis of genuine graduate-level science would be ideally equipped for this task. Recognition of this potential niche has been slow among graduate programs in philosophy, but there is some hope that a few programs are taking steps to fill it.

In the final analysis there will be philosophers unprepared to accept that, if a given cognitive capacity is psychologically real, then there must be an explanation of how it is possible for an individual in the course of human development to acquire that cognitive capacity, or anything like it, can have a role to play in philosophical accounts of concepts and conceptual abilities. The most obvious basis for such a view would be a Frégean distrust of psychology that leads to a rigid division of labour between philosophy and psychology. The operative thought is that the task of a philosophical theory of concepts is to explain what a given concept is or what a given conceptual ability consist in. This, it is frequently maintained, is something that can be done in complete independence of explaining how such a concept or ability might be acquired. The underlying distinction is one between philosophical questions cantering around concept possession and psychological questions cantering around concept possibilities for an individual to acquire that ability, then it cannot be psychologically real. Nevertheless, this distinction is strictly one that agrees in the adherence to the distinction, it provides no support for a rejection of any given cognitive capacity for which is psychologically real. The neo-Frégean distinction is directly against the view that facts about how concepts are acquired have a role to play in explaining and individualizing concepts. But this view does not have to be disputed by a supporter as such, nonetheless, all that the supporter is to commit is that the principle that no satisfactory account of what a concept is should make it impossible to provide explanation of how that concept can be acquired. That is, that this principle has nothing to say about the further question of whether the psychological explanation has a role to play in a constitutive explanation of the concept, and hence is not in conflict with the neo-Frégean distinction.

A full account of the structure of consciousness, will employ a pressing opportunity or requirements to provide that to illustrate those higher conceptual representations as given to forms of consciousness, to which little attention on such an account will take and about how it might emerge from given points of value, is the thought that an explanation of everything that is distinctive about consciousness will emerge out of an accorded advantage over and above of what it is for the subject, to be capable of thinking about himself. Nonetheless, to appropriate a convenient employment with an applicable understanding of the complicated and complex phenomenon of consciousness, however, ours is to challenge the arousing objectionable character as attributed by the attractions of an out-and-out form of consciousness. Seeming to be the most basic of facts confronting us, yet, it is almost impossible to say what consciousness is. Whenever complicated and complex biological and neural processes go on between the cranial walls of existent vertebrae, as it is my consciousness that provides the medium, though which my consciousness provides the awakening flame of awareness which enables me to think, and if there is no thinking, there is no sense of consciousness. Which their existence the possibility to envisage the entire moral and political framework constructed to position of ones idea of interactions to hold a person rationally approved, although the development of requirement needed of the motivational view as well as the knowledge for which is rationality and situational of the agent.

Meanwhile, whatever complex biological and neural processes go on within the mind, it is my consciousness that provides the awakening awarenesses, whereby my experiences and thoughts have their existence, where my desires are felt and where my intentions are formed. But then how am I to expound upon the I-ness of me or myself that the self is the spectator, or at any rate the owner of this afforded effort as spoken through the strength of the imagination, that these problems together make up what is sometimes called the hard problem of consciousness. One of the difficulties is thinking about consciousness is that the problems seem not to be scientific ones, as the German philosopher, mathematician and polymath Gottfried Leibniz (1646-1716), remarked that if we could construct a machine that could think and feel and then blow it up to the size of a football field and thus be able to examine its working parts as thoroughly as we pleased, would still not find consciousness. And finally, drew to some conclusion that consciousness resides in simple subjects, not complex ones. Even if we are convinced that consciousness somehow emerges from the complexity of the brain functioning, we may still feel baffled about the ways that emergencies takes place, or it takes place in just the way it does. Seemingly, to expect is a prime necessity for ones own personal expectations, even so, to expect of expectation is what is needed of opposites, such that there is no positivity to expect, however, to accept of the doubts that are none, so that the expectation as a forerunner to expect should be nullified. Descartes deceptions of the senses are nothing but a clear orientation of something beyond expectation, indeed.

There are no facts about linguistic mastery that will determine or explain what might be termed the cognitive dynamics that are individual processes that have found their way forward for a theory of consciousness, it sees, to chart the characteristic features individualizing the various distinct conceptual forms of consciousness in a way that will provide a taxonomy of unconsciousness is to show how this actualization is the characterlogical contribution of functional dynamic determinations, that, if, not at least, at the level of contentual representation. What is hoping is now clear is that these forms of higher forms of consciousness emerge from a rich foundation of non-conceptual representations of thought, which can only expose and clarify their conviction that these forms of conscious thought hold the key, not just to an eventful account of how mastery of the conscious paradigms, but to a proper understanding of the plexuity of self-consciousness and/or the overall conjecture of consciousness that stands alone as to an everlasting vanquishment into the endlessness of unchangeless states of unconsciousness, where its abysses are only held by incestuousness.

Theory itself, is consistent with fact or reality, not false or incorrect, but truthful, it is sincerely felt or expressed unforeignly and so, that it is essential and exacting of several standing rules and senses of governing requirements. As, perhaps, the distress of mind begins its lamination of binding substances through which arises of an intertwined web whereby that within and without the estranging assimilations in sensing the definitive criteria by some limited or restrictive particularities of some possible value as taken by a variable accord with reality. To position of something, as to make it balanced, level or square, that we may think of a proper alignment as something, in so, that one is certain, like trust, another derivation of the same appears on the name is etymologically, or strong seers. Conformity of fact or the actuality of a statement as been or accepted as true to an original or standard set class theory from which it is considered as the supreme reality and to have the ultimate meaning, and value of existence. It is, nonetheless, a compound position, such as a conjunction or negation, the truth-values have always determined whose truth-values of that component thesis.

Moreover, science, unswerving exactly to position of something very well hidden, its nature in so that to make it believed, is quickly and imposes on sensing and responding to the definitive qualities or state of being actual or true, such that as a person, an entity, or an event, that might be gainfully employed of all things possessing actuality, existence, or essence. In other words, in that which is objectively inside and out, and in addition it seems to appropriate that of reality, in fact, to the satisfying factions of instinctual needs through the awarenesses of and adjustments abided to environmental demands. Thus, the enabling acceptation of a presence that to prove the duties or function of such that the act or part thereof, that something done or effected presents upon our understanding or plainly the condition of truth which is seen for being realized, and the resultant amounts to the remnant retrogressions that are also, undoubtingly realized.

However, a declaration made to explain or justify action, or its believing desire upon which it is to act, by which the conviction underlying facts or cause, that provide logical sense for a premise or occurrence for logical, rational. Analytic mental states have long since lost in reason, but, yet, the premise usually takes upon the minor premises of an argument, using this faculty of reason that arises too throughout the spoken exchange or a debative discussion, and, of course, spoken in a dialectic way. To determining or conclusively logical impounded by thinking through its directorial solution to the problem, would therefore persuade or dissuade someone with reason that posits of itself with the good sense or justification of reasonability. In which, good causes are simply justifiably to be considered as to think. By which humans seek or attain knowledge or truth. Mere reason is insufficient to convince us of its veracity. Still, comprehension perceptively welcomes an intuitively given certainty, as the truth or fact, without the use of the rational process, as one comes to assessing someones character, it sublimely configures one consideration, and often with resulting comprehensions, in which it is assessing situations or circumstances and draw sound conclusions into the reign of judgement.

Operatively, that by being in accorded with reason or, perhaps, of sound thinking, that the discovery made, is by some reasonable solution that may or may not resolve the problem, that being without the encased enclosure that bounds common sense from arriving to some practicality, especially if using reason, would posit the formed conclusions, in that of inferences or judgements. In that, all evidential alternates of a confronting argument within the use in thinking or thought out responses to issuing the furthering argumentation to fit or join in the sum parts that are composite to the intellectual faculties, by which case human understanding or the attemptive grasp to its thought, are the resulting liberty encroaching men of zeal, well-meaningly, but without understanding.

Being or occurring in fact or having to some verifiable existence, real objects, and a real illness. . . .Really true and actual and not imaginary, alleged, or ideal, as people and not ghosts, from which are we to find on practical matters and concerns of experiencing the real world. The surrounding surfaces, might we, as, perhaps attest to this for the first time. Being no less than what they state, we have not taken its free pretence, or affections for a real experience highly, as many may encounter real trouble. This, nonetheless, projects of an existing objectivity in which the world despite subjectivity or conventions of thought or language is or have valuing representation, reckoned by actual power, in that of relating to, or being an image formed by light or another identifiable simulation, that converge in space, the stationary or fixed properties, such as a thing or whole having actual existence. All of which, are accorded a truly factual experience into which the actual attestations have brought to you by the afforded efforts of our very own imaginations.

Ideally, in theory the imagination, a concept of reason that is transcendent but non-empirical as to think os conception of and ideal thought, that potentially or actual exists in the mind as a product exclusive to the mental act. In the philosophy of Plato, an archetype of which a corresponding being in phenomenal reality is an imperfect replica, that also, Hegels absolute truth, as the conception and ultimate product of reason (the absolute meaning a mental image of something remembered).

Conceivably, in the imagination the formation of a mental image of something that is or should be b perceived as real nor present to the senses. Nevertheless, the image so formed can confront and deal with the reality by using the creative powers of the mind. That is characteristically well removed from reality, but all powers of fantasy over reason are a degree of insanity/ still, fancy as they have given a product of the imagination free reins, that is in command of the fantasy while it is exactly the mark of the neurotic that his very own fantasy possesses him.

All things possessing actuality, existence or essence that exists objectively and in fact based on real occurrences that exist or known to have existed, a real occurrence, an event, i.e., had to prove the facts of the case, as something believed to be true or real, determining by evidence or truth as to do. However, the usage in the sense allegation of fact, and the reasoning are wrong of the facts and substantive facts, as we may never know the facts of the case. These usages may occasion qualms among critics who insist that facts can only be true, but the usages are often useful for emphasis. Therefore, we have related to, or used the discovery or determinations of fast or accurate information in the discovery of facts, then evidence has determined the comprising events or truth is much as ado about their owing actuality. Its opposition forming the literature that treats real people or events as if they were fictional or uses real people or events as essential elements in an otherwise fictional rendition, i.e., of, relating to, produced by, or characterized by internal dissension, as given to or promoting internal dissension. So, then, it is produced artificially than by a natural process, especially the lacking authenticity or genuine factitious values of another than what is or of reality should be.

Substantively set statements or principles devised to explain a group of facts or phenomena, especially one that we have tested or is together experiment with and taken for us to conclude and can be put-upon to make predictions about natural phenomena. Having the consistency of explanatory statements, accepted principles, and methods of analysis, finds to a set of theorems that make up a systematic view of a branch in mathematics or extends upon the paradigms of science, the belief or principle that guides action or helps comprehension or judgements, usually by an ascription based on limited information or knowledge, as a conjecture, tenably to assert the creation from a speculative assumption that bestows to its beginning. Theoretically, to, affiliate oneself with to, or based by itself on theory, i.e., the restriction to theory, is not as much a practical theory of physics, as given to speculative theorizing. Also, the given idea, because of which formidable combinations awaiting upon the inception of an idea, demonstrated as true or is given to demonstration. In mathematics its containment lies of the proposition that has been or is to be proved from explicit assumption and is primarily with theoretical assessments or hypothetical theorizing than possibly these might be thoughtful measures and taken as the characteristics by which we measure its quality value?

Looking back, one can see a discovering degree of homogeneity among the philosophers of the early twentieth century about the topics central to their concerns. More striking still, is the apparent profundities and abstrusity of concerns for which appear at first glance to be separated from the discerned debates of previous centuries, between realism and idealist, say, of rationalists and empiricist.

Thus, no matter what the current debate or discussion, the central issue is often without conceptual and contentual representations, that if one is without concept, is without idea, such that in one foul swoop would ingest the mere truth that lies to the underlying paradoxes of why is there something instead of nothing? Whatever it is that makes, what would otherwise be mere utterances and inscriptions into instruments of communication and understanding. This philosophical problem is to demystify this over-flowing emptiness, and to relate to what we know of ourselves and subjective matters resembling reality or ours is to an inherent perceptivity of the world and its surrounding surfaces.

Contributions to this study include the theory of speech arts, and the investigation of communicable communications, especially the relationship between words and ideas, and words and the world. It is, nonetheless, that which and utterance or sentence expresses, the proposition or claim made about the world. By extension, the content of a predicate that any expression effectively connecting with one or more singular terms to make a sentence, the expressed condition that the entities referred to may satisfy, in which case the resulting sentence will be true. Consequently we may think of a predicate as a function from things to sentences or even to truth-values, or other sub-sentential components that contribute to sentences that contain it. The nature of content is the central concern of the philosophy of language.

What some person expresses of a sentence often depends on the environment in which he or she is placed. For example, the disease I refer to by a term like arthritis or the kind of tree I call of its criteria will define a beech of which I know next to nothing. This raises the possibility of imaging two persons as an alternative different environment, but in which everything appears the same to each of them. The wide content of their thoughts and saying will be different if the situation surrounding them is appropriately different, situation may here include the actual objects hey perceive, or the chemical or physical kinds of objects in the world they inhabit, or the history of their words, or the decisions of authorities on what counts as an example of one term thy use. The narrow content is that part of their thought that remains identical, through the identity of the way things appear, despite these differences of surroundings. Partisans of wide, . . . as, something called broadly, content may doubt whether any content is in this sense narrow, partisans of narrow content believe that it is the fundamental notion, with wide content being on narrow content confirming context.

All and all, assuming their rationality has characterized people is common, and the most evident display of our rationality is capable to think. This is the rehearsal in the mind of what to say, or what to do. Not all thinking is verbal, since chess players, composers, and painters all think, and there is no deductive reason that their deliberations should take any more verbal a form than their actions. It is permanently tempting to conceive of this activity about the presence in the mind of elements of some language, or other medium that represents aspects of the world and its surrounding surface structures. However, the model has been attacked, notably by Ludwig Wittgenstein (1889-1951), whose influential application of these ideas was in the philosophy of mind. Wittgenstein explores the role that reports of introspection, or sensations, or intentions, or beliefs can play of our social lives, to undermine the Cartesian mental picture is that they functionally describe the goings-on in an inner theatre of which the subject is the lone spectator. Passages that have subsequentially become known as the rule following considerations and the private language argument are among the fundamental topics of modern philosophy of language and mind, although their precise interpretation is endlessly controversial.

Effectively, the hypotheses especially associated with Jerry Fodor (1935-), whom is known for the resolute realism, about the nature of mental functioning, that occurs in a language different from ones ordinary native language, but underlying and explaining our competence with it. The idea is a development of the notion of an innate universal grammar (Avram Noam Chomsky, 1928-), in as such, that we agree that since a computer programs are linguistically complex sets of instructions were the relative executions by which explains of surface behaviour or the adequacy of the computerized programming installations, if it were definably amendable and, advisably corrective, in that most are disconcerting of many that are ultimately a reason for us of thinking intuitively and without the indulgence of retrospective preferences, but an ethical majority in defending of its moral line that is already confronting us. That these programs may or may not improve to conditions that are lastly to enhance of the right sort of an existence forwarded toward a more valuing amount in humanities lesser extensions that embrace ones riff of necessity to humanities abeyance to expressions in the finer of qualities.

As an explanation of ordinary language-learning and competence, the hypothesis has not found universal favour, as only ordinary representational powers that by invoking the image of the learning persons capabilities are apparently whom the abilities for translating are contending of an innate language whose own powers are mysteriously a biological given. Perhaps, the view that everyday attributions of intentionality, beliefs, and meaning to other persons proceed by means of a tactic use of a theory that enables one to construct these interpretations as explanations of their doings. We commonly hold the view along with functionalism, according to which psychological states are theoretical entities, identified by the network of their causes and effects. The theory-theory has different implications, depending upon which feature of theories we are stressing. Theories may be thought of as capable of formalization, as yielding predictions and explanations, as achieved by a process of theorizing, as answering to empirical evidence that is in principle describable without them, as liable to be overturned by newer and better theories, and so on.

The main problem with seeing our understanding of others as the outcome of a piece of theorizing is the nonexistence of a medium in which this theory can be couched, as the child learns simultaneously the minds of others and the meaning of terms in its native language, is not gained by the tactic use of a theory, enabling us to infer what thoughts or intentions explain their actions, but by re-living the situation in their shoes or from their point of view, and by that understanding what they experienced and theory, and therefore expressed. Understanding others is achieved when we can ourselves deliberate as they did, and hear their words as if they are our own. The suggestion is a modern development frequently associated in the verstehen traditions of Dilthey (1833-1911), Weber (1864-1920) and Collingwood (1889-1943).

We may call any process of drawing a conclusion from a set of premises a process of reasoning. If the conclusion concerns what to do, the process is called practical reasoning, otherwise pure or theoretical reasoning. Evidently, such processes may be good or bad, if they are good, the premises support or even entail the conclusion drawn, and if they are bad, the premises offer no support to the conclusion. Formal logic studies the cases in which conclusions are validly drawn from premises, but little human reasoning is overly of the forms logicians identify. Partly, we are concerned to draw conclusions that go beyond our premises, in the way that conclusions of logically valid arguments do not for the process of using evidence to reach a wider conclusion. Nonetheless, such anticipatory pessimism in the opposite direction to the prospects of conformation theory, denying that we can assess the results of abduction in terms of probability. A cognitive process of reasoning in which a conclusion is played-out from a set of premises usually confined of cases in which the conclusions are supposed in following from the premises, i.e., an inference is logically valid, in that of deductibility in a logically defined syntactic premise but without there being to any reference to the intended interpretation of its theory. Furthermore, as we reason we use indefinite traditional knowledge or commonsense sets of presuppositions about what it is likely or not a task of an automated reasoning project, which is to mimic this causal use of knowledge of the way of the world in computer programs.

Some theories usually emerge themselves of engaging to exceptionally explicit predominancy as [ supposed ] truths that they have not organized, making the theory difficult to survey or study as a whole. The axiomatic method is an idea for organizing a theory, one in which tries to select from among the supposed truths a small number from which they can see all others to be deductively inferable. This makes the theory more tractable since, in a sense, they contain all truths in those few. In a theory so organized, they call the few truths from which they deductively imply all others axioms. David Hilbert (1862-1943) had argued that, just as algebraic and differential equations, which we were used to study mathematical and physical processes, could have themselves be made mathematical objects, so axiomatic theories, like algebraic and differential equations, which are means to representing physical processes and mathematical structures could be of investigating.

Conformation to theory, the philosophy of science, is a generalization or set referring to unobservable entities, i.e., atoms, genes, quarks, unconscious wishes. The ideal gas law, for example, refers to such observable pressures, temperature, and volume, the molecular-kinetic theory refers to molecules and their material possession, . . . although an older usage suggests the lack of adequate evidence in support thereof, as an existing philosophical usage does in truth, follow in the tradition (as in Leibniz, 1704), as many philosophers had the conviction that all truths, or all truths about a particular domain, followed from as few than for being many governing principles. These principles were taken to be either metaphysically prior or epistemologically prior or both. In the first sense, they we took to be entities of such a nature that what exists s caused by them. When the principles were taken as epistemologically prior, that is, as axioms, they were taken to be either epistemologically privileged, e.g., self-evident, not needing to be demonstrated, or again, included or, to such that all truths so truly follow from them by deductive inferences. Gödel (1984) showed in the spirit of Hilbert, treating axiomatic theories as themselves mathematical objects that mathematics, and even a small part of mathematics, elementary number theory, could not be axiomatized, that more precisely, any class of axioms that is such that we could effectively decide, of any proposition, whether or not it was in that class, would be too small to capture in of the truths.

The notion of truth occurs with remarkable frequency in our reflections on language, thought and action. We are inclined to suppose, for example, that truth is the proper aim of scientific inquiry, that true beliefs help to achieve our goals, that to understand a sentence is to know which circumstances would make it true, that reliable preservation of truth as one argues of valid reasoning, that moral pronouncements should not be regarded as objectively true, and so on. To assess the plausibility of such theses, and to refine them and to explain why they hold (if they do), we require some view of what truth be a theory that would account for its properties and its relations to other matters. Thus, there can be little prospect of understanding our most important faculties in the sentence of a good theory of truth.

Such a thing, however, has been notoriously elusive. The ancient idea that truth is some sort of correspondence with reality has still never been articulated satisfactorily, and the nature of the alleged correspondence and the alleged reality persistently remains objectionably enigmatical. Yet the familiar alternative suggestions that true beliefs are those that are mutually coherent, or pragmatically useful, or verifiable in suitable conditions has each been confronted with persuasive counterexamples. A twentieth-century departure from these traditional analyses is the view that truth is not a property at all that the syntactic form of the predicate, is true, distorts its really semantic character, which is not to describe propositions but to endorse them. Nevertheless, we have also faced this radical approach with difficulties and suggest, counter intuitively that truth cannot have the vital theoretical role in semantics, epistemology and elsewhere that we are naturally inclined to give it. Thus, truth threatens to remain one of the most enigmatic of notions: An explicit account of it can seem essential yet beyond our reach. All the same, recent work provides some evidence for optimism.

A theory is based in philosophy of science, is a generalization or se of generalizations purportedly referring to observable entities, i.e., atoms, quarks, unconscious wishes, and so on. The ideal gas law, for example, cites to only such observable pressures, temperature, and volume, the molecular-kinetic theory refers top molecules and their properties, although an older usage suggests the lack of an adequate make out in support therefrom as merely a theory, latter-day philosophical usage does not carry that connotation. Einsteins special and General Theory of Relativity, for example, is taken to be extremely well founded.

These are two main views on the nature of theories. According to the received view theories are partially interpreted axiomatic systems, according to the semantic view, a theory is a collection of models (Suppe, 1974). By which, some possibilities, unremarkably emerge as supposed truths that no one has neatly systematized by making theory difficult to make a survey of or study as a whole. The axiomatic method is an ideal for organizing a theory (Hilbert, 1970), one tries to select from among the supposed truths a small number from which they can see all the others to be deductively inferable. This makes the theory more tractable since, in a sense, they contain all truths in those few. In a theory so organized, they call the few truths from which they deductively incriminate all others axioms. David Hilbert (1862-1943) had argued that, morally justified as algebraic and differential equations, which were antiquated into the study of mathematical and physical processes, could hold on to themselves and be made mathematical objects, so they could make axiomatic theories, like algebraic and differential equations, which are means of representing physical processes and mathematical structures, objects of mathematical investigation.

In the tradition (as in Leibniz, 1704), many philosophers had the conviction that all truths, or all truths about a particular domain, followed from a few principles. These principles were taken to be either metaphysically prior or epistemologically prior or both. In the first sense, they were taken to be entities of such a nature that what exists is caused by them. When the principles were taken as epistemologically prior, that is, as axioms, they were taken to be either epistemologically privileged, i.e., self-evident, not needing to be demonstrated, or again, inclusive or, to be such that all truths do in truth follow from them (by deductive inferences). Gödel (1984) showed in the spirit of Hilbert, treating axiomatic theories as themselves mathematical objects that mathematics, and even a small part. Of mathematics, elementary number theory, could not be axiomatized, that, more precisely, any class of axioms that is such that we could effectively decide, of any proposition, whether or not it was in that class, would be too small to capture all of the truths.

The notion of truth occurs with remarkable frequency in our reflections on language, thought, and action. We are inclined to suppose, for example, that truth is the proper aim of scientific inquiry, that true beliefs help us to achieve our goals, tat to understand a sentence is to know which circumstances would make it true, that reliable preservation of truth as one argues from premises to a conclusion is the mark of valid reasoning, that moral pronouncements should not be regarded as objectively true, and so on. In order to assess the plausible of such theses, and in order to refine them and to explain why they hold, if they do, we expect some view of what truth be of a theory that would keep an account of its properties and its relations to other matters. Thus, there can be little prospect of understanding our most important faculties without a good theory of truth.

The ancient idea that truth is one sort of correspondence with reality has still never been articulated satisfactorily: The nature of the alleged correspondence and te alleged reality remains objectivably rid of obstructions. Yet, the familiar alternative suggests ~. That true beliefs are those that are mutually coherent, or pragmatically useful, or verifiable in suitable conditions has each been confronted with persuasive counterexamples. A twentieth-century departure from these traditional analyses is the view that truth is not a property at al ~. That the syntactic form of the predicate, . . . is true, distorts the real semantic character, with which is not to describe propositions but to endorse them. Still, this radical approach is also faced with difficulties and suggests, counter intuitively that truth cannot have the vital theoretical role in semantics, epistemology and elsewhere that we are naturally inclined to give it. Thus, truth threatens to remain one of the most enigmatic of notions, and a confirming account of it can seem essential yet, on the far side of our reach. However, recent work provides some grounds for optimism.

The belief that snow is white owes its truth to a certain feature of the external world, namely, to the fact that snow is white. Similarly, the belief that dogs bark is true because of the fact that dogs bark. This trivial observation leads to what is perhaps the most natural and popular account of truth, the correspondence theory, according to which a belief (statement, a sentence, propositions, etc. (as true just in case there exists a fact corresponding to it (Wittgenstein, 1922, Austin! 950). This thesis is unexceptionable, however, if it is to provide a rigorous, substantial and complete theory of truth ~. If it is to be more than merely a picturesque way of asserting all equivalences to the form. The belief that p is true p.

Then it must be supplemented with accounts of what facts are, and what it is for a belief to correspond to a fact, and these are the problems on which the correspondence theory of truth has floundered. For one thing, it is far from going unchallenged that any significant gain in understanding is achieved by reducing the belief that snow is white is true to the facts that snow is white exists: For these expressions look equally resistant to analysis and too close in meaning for one to provide a crystallizing account of the other. In addition, the undistributed relationship that holds in particular between the belief that snow is white and the fact that snow is white, between the belief that dogs bark and the fact that a dog barks, and so on, is very hard to identify. The best attempt to date is Wittgensteins 1922, so-called picture theory, by which an elementary proposition is a configuration of terms, with whatever stare of affairs it reported, as an atomic fact is a configuration of simple objects, an atomic fact corresponds to an elementary proposition and makes it true, when their configurations are identical and when the terms in the proposition for it to the similarly-placed objects in the fact, and the truth value of each complex proposition the truth values entail of the elementary ones. However, eve if this account is correct as far as it goes, it would need to be completed with plausible theories of logical configuration, rudimentary proposition, reference and entailment, none of which is better-off to come.

The cental characteristic of truth One that any adequate theory must explain is that when a proposition satisfies its conditions of proof or verification then it is regarded as true. To the extent that the property of corresponding with reality is mysterious, we are going to find it impossible to see what we take to verify a proposition should show the possession of that property. Therefore, a tempting alternative to the correspondence theory an alternative that eschews obscure, metaphysical concept that explains quite straightforwardly why Verifiability infers, truth is simply to identify truth with Verifiability (Peirce, 1932). This idea can take on variously formed. One version involves the further assumption that verification is holistic, . . . in that a belief is justified (i.e., verified) when it is part of an entire system of beliefs that are consistent and counter balanced (Bradley, 1914 and Hempel, 1935). This is known as the coherence theory of truth. Another version involves the assumption associated with each proposition, some specific procedure for finding out whether one should believe it or not. On this account, to say that a proposition is true is to sa that the appropriate procedure would verify (Dummett, 1979. and Putnam, 1981). While mathematics this amounts to the identification of truth with provability.

The attractions of the verificationist account of truth are that it is refreshingly clear compared with the correspondence theory, and that it succeeds in connecting truth with verification. The trouble is that the bond it postulates between these notions is implausibly strong. We do in true statements take verification to indicate truth, but also we recognize the possibility that a proposition may be false in spite of there being impeccable reasons to believe it, and that a proposition may be true although we are not able to discover that it is. Verifiability and ruth are no doubt highly correlated, but surely not the same thing.

A third well-known account of truth is known as pragmatism (James, 1909 and Papineau, 1987). As we have just seen, the verificationist selects a prominent property of truth and considers the essence of truth. Similarly, the pragmatist focuses on another important characteristic namely, that true belief is a good basis for action and takes this to be the very nature of truth. True assumpsitions are said to be, by definition, those that provoke actions with desirable results. Again, we have an account statement with a single attractive explanatory characteristic, besides, it postulates between truth and its alleged analysand in this case, utility is implausibly close. Granted, true belief tends to foster success, but it happens regularly that actions based on true beliefs lead to disaster, while false assumptions, by pure chance, produce wonderful results.

One of the few uncontroversial facts about truth is that the proposition that snow is white if and only if snow is white, the proposition that lying is wrong is true if and only if lying is wrong, and so on. Traditional theories acknowledge this fact but regard it as insufficient and, as we have seen, inflate it with some further principle of the form, X is true if and only if X has property P (such as corresponding to reality, Verifiability, or being suitable as a basis for action), which is supposed to specify what truth is. Some radical alternatives to the traditional theories result from denying the need for any such further specification (Ramsey, 1927, Strawson, 1950 and Quine, 1990). For example, ne might suppose that the basic theory of truth contains nothing more that equivalences of the form, The proposition that p is true if and only if p (Horwich, 1990).

That is, a proposition, K with the following properties, that from K and any further premises of the form. Einsteins claim was the proposition that p you can imply p. Whatever it is, now supposes, as the deflationist says, that our understanding of the truth predicate consists in the stimulative decision to accept any instance of the schema. The proposition that p is true if and only if p, then your problem is solved. For K is the proposition, Einsteins claim is true , it will have precisely the inferential power needed. From it and Einsteins claim is the proposition that quantum mechanics are wrong, you can use Leibnizs law to imply The proposition that quantum mechanic is wrong is true; which given the relevant axiom of the deflationary theory, allows you to derive Quantum mechanics is wrong. Thus, one point in favour of the deflationary theory is that it squares with a plausible story about the function of our notion of truth, in that its axioms explain that function without the need for further analysis of what truth is.

Not all variants of deflationism have this quality virtue, according to the redundancy performatives theory of truth, the pair of sentences, The proposition that p is true and plain ps, has the same meaning and expresses the same statement as one and another, so it is a syntactic illusion to think that p is true attributes any sort of property to a proposition (Ramsey, 1927 and Strawson, 1950). Yet in that case, it becomes hard to explain why we are entitled to infer The proposition that quantum mechanics are wrong is true form Einsteins claim is the proposition that quantum mechanics are wrong. Einsteins claim is true. For if truth is not property, then we can no longer account for the inference by invoking the law that if X, appears identical with Y then any property of X is a property of Y, and vice versa. Thus the redundancy/performatives theory, by identifying rather than merely correlating the contents of The proposition that p is true and p, precludes the prospect of a good explanation of one on truths most significant and useful characteristics. So, putting restrictions on our assembling claim to the weak is better, of its equivalence schema: The proposition that p is true is and is only p.

Support for deflationism depends upon the possibleness of showing that its axiom instances of the equivalence schema unsupplements by any further analysis, will suffice to explain all the central facts about truth, for example, that the verification of a proposition indicates its truth, and that true beliefs have a practical value. The first of these facts follows trivially from the deflationary axioms, for given ours a prior knowledge of the equivalence of p and The a propositions that p is true, any reason to believe that p becomes an equally good reason to believe that the preposition that p is true. We can also explain the second fact in terms of the deflationary axioms, but not quite so easily. Consider, to begin with, beliefs of the form that if I perform the act A, then my desires will be fulfilled. Notice that the psychological role of such a belief is, roughly, to cause the performance of A. In other words, given that I do have belief, then typically.

I will perform the act A

Notice also that when the belief is true then, given the deflationary axioms, the performance of A will in fact lead to the fulfilment of ones desires, i.e., If being true, then if I perform A, and my desires will be fulfilled.

Therefore, if it is true, then my desires will be fulfilled. So valuing the truth of beliefs of that form is quite treasonable. Nevertheless, inference has derived such beliefs from other beliefs and can be expected to be true if those other beliefs are true. So assigning a value to the truth of any belief that might be used in such an inference is reasonable.

To the extent that such deflationary accounts can be given of all the acts involving truth, then the explanatory demands on a theory of truth will be met by the collection of all statements like, The proposition that snow is white is true if and only if snow is white, and the sense that some deep analysis of truth is needed will be undermined.

Nonetheless, there are several strongly felt objections to deflationism. One reason for dissatisfaction is that the theory has an infinite number of axioms, and therefore cannot be completely written down. It can be described, as the theory whose axioms are the propositions of the fore p if and only if it is true that p, but not explicitly formulated. This alleged defect has led some philosophers to develop theories that show, first, how the truth of any proposition derives from the referential properties of its constituents, and second, how the referential properties of primitive constituents are determinated (Tarski, 1943 and Davidson, 1969). However, assuming that all propositions including belief attributions remain controversial, law of nature and counterfactual conditionals depends for their truth values on what their constituents refer to implicate. In addition, there is no immediate prospect of a presentable, finite possibility of reference, so that it is far form clear that the infinite, list-like character of deflationism can be avoided.

Additionally, it is commonly supposed that problems about the nature of truth are intimately bound up with questions as to the accessibility and autonomy of facts in various domains: Questions about whether the facts can be known, and whether they can exist independently of our capacity to discover them (Dummett, 1978, and Putnam, 1981). One might reason, for example, that if T is true means nothing more than T will be verified, then certain forms of scepticism, specifically, those that doubt the correctness of our methods of verification, that will be precluded, and that the facts will have been revealed as dependent on human practices. Alternatively, it might be said that if truth were an inexplicable, primitive, non-epistemic property, then the fact that T is true would be completely independent of us. Moreover, we could, in that case, have no reason to assume that the propositions we believe in, that in adopting its property, so scepticism would be unavoidable. In a similar vein, it might be thought that as special, and perhaps undesirable features of the deflationary approach, is that truth is deprived of such metaphysical or epistemological implications.

Upon closer scrutiny, in that, it is far from clear that there exists any account of truth with consequences regarding the accessibility or autonomy of non-semantic matters. For although an account of truth may be expected to have such implications for facts of the form T is true, it cannot be assumed without further argument that the same conclusions will apply to the fact T. For it cannot be assumed that T and T are true and is equivalent to one another given the account of true that is being employed. Of course, if truth is defined in the way that the deflationist proposes, then the equivalence holds by definition. Nevertheless, if truth is defined by reference to some metaphysical or epistemological characteristic, then the equivalence schema is thrown into doubt, pending some demonstration that the trued predicate, in the sense assumed, will be satisfied in as far as there are thought to be epistemological problems hanging over Ts that do not threaten T is true, giving the needed demonstration will be difficult. Similarly, if truth is so defined that the fact, T is felt to be more, or less, independent of human practices than the fact that T is true, then again, it is unclear that the equivalence schema will hold. It would seem, therefore, that the attempt to base epistemological or metaphysical conclusions on a theory of truth must fail because in any such attempt the equivalence schema will be simultaneously relied on and undermined.

The most influential idea in the theory of meaning in the past hundred yeas is the thesis that meaning of an indicative sentence is given by its truth-conditions. On this conception, to understand a sentence is to know its truth-conditions. The conception was first clearly formulated by Frége (1848-1925), was developed in a distinctive way by the early Wittgenstein (1889-1951), and is a leading idea of Davidson (1917-). The conception has remained so central that those who offer opposing theories characteristically define their position by reference to it.

The conception of meaning as truth-conditions necessarily are not and should not be advanced as a complete account of meaning. For instance, one who understands a language must have some idea of the range of speech acts conventionally acted by the various types of a sentence in the language, and must have some idea of the significance of various kinds of speech acts. The claim of the theorist of truth-conditions should as an alternative is targeted on the notion of content: If two indicative sentences differ in what they strictly and literally say, then this difference is fully accounted for by the difference in their truth-conditions. Most basic to truth-conditions is simply of a statement that is the condition the world must meet if the statement is to be true. To know this condition is equivalent to knowing the meaning of the statement. Although this sounds as if it gives a solid anchorage for meaning, some of the security disappears when it turns out that the truth condition can only be defined by repeating the very same statement, as a truth condition of snow is white is that snow is white, the truth condition of Britain would have capitulated had Hitler invaded is the Britain would have capitulated had Hitler invaded. It is disputed whether this element of running-on-the-spot disqualifies truth conditions from playing the central role in a substantive theory of meaning. Truth-conditional theories of meaning are sometimes opposed by the view that to know the meaning of a statement is to be able to use it in a network of inferences.

Whatever it is that makes, what would otherwise be mere sounds and inscriptions into instruments of communication and understanding. The philosophical problem is to demystify this power, and to relate it to what we know of ourselves and the world. Contributions to the study include the theory of speech acts and the investigation of communication and the relationship between words and ideas and the world and surrounding surfaces, by which some persons express by a sentence are often a function of the environment in which he or she is placed. For example, the disease I refer to by a term like arthritis or the kind of tree I refer to as a maple will be defined by criteria of which I know next to nothing. The raises the possibility of imagining two persons in alternatively differently environmental, but in which everything appears the same to each of them, but between them they define a space of philosophical problems. They are the essential components of understanding nd any intelligible proposition that is true must be capable of being understood. Such that which is expressed by an utterance or sentence, the proposition or claim made about the world may by extension, the content of a predicated or other sub-sentential component is what it contributes to the content of sentences that contain it. The nature of content is the cental concern of the philosophy of language.

In particularly, the problems of indeterminancy of translation, inscrutability of reference, language, predication, reference, rule following, semantics, translation, and the topics referring to subordinate headings associated with logic. The loss of confidence in determinate meaning (Each is another encoding) is an element common both to postmodern uncertainties in the theory of criticism, and to the analytic tradition that follows writers such as Quine (1908-). Still it may be asked, why should we suppose that fundamental epistemic notions should be keep an account of for in behavioural terms what grounds are there for supposing that p knows p is a subjective matter in the prestigiousness of its statement between some subject statement and physical theory of physically forwarded of an objection, between nature and its mirror? The answer is that the only alternative seems to be to take knowledge of inner states as premises from which our knowledge of other things is normally implied, and without which our knowledge of other things is normally inferred, and without which knowledge would be ungrounded. However, it is not really coherent, and does not in the last analysis make sense, to suggest that human knowledge have foundations or grounds. It should be remembered that to say that truth and knowledge can only be judged by the standards of our own day is not to say that it is less meaningful nor is it more cut off from the world, which we had supposed. Conjecturing it is as just that nothing counts as justification, unless by reference to what we already accept, and that at that place is no way to get outside our beliefs and our oral communication so as to find some experiment with others than coherence. The fact is that the professional philosophers have thought it might be otherwise, since one and only they are haunted by the clouds of epistemological scepticism.

What Quine opposes as residual Platonism is not so much the hypostasising of non-physical entities as the notion of correspondence with things as the final court of appeal for evaluating present practices. Unfortunately, Quine, for all that it is incompatible with its basic insights, substitutes for this correspondence to physical entities, and specially to the basic entities, whatever they turn out to be, of physical science. Nevertheless, when their doctrines are purified, they converge on a single claim. That no account of knowledge can depend on the assumption of some privileged relations to reality. Their work brings out why an account of knowledge can amount only to a description of human behaviour.

What, then, is to be said of these inner states, and of the direct reports of them that have played so important a role in traditional epistemology? For a person to feel is nothing else than for him to have an ability to make a certain type of non-inferential report, to attribute feelings to infants is to acknowledge in them latent abilities of this innate kind. Non-conceptual, non-linguistic knowledge of what feelings or sensations is like is attributively to beings on the basis of potential membership of our community. Infants and the more attractive animals are credited with having feelings on the basis of that spontaneous sympathy that we extend to anything humanoid, in contrast with the mere response to stimuli attributed to photoelectric cells and to animals about which no one feels sentimentally. Supposing that moral prohibition against hurting infants is consequently wrong and the better-looking animals are; those moral prohibitions grounded in their possession of feelings. The relation of dependence is really the other way round. Similarly, we could not be mistaken in supposing that a four-year-old child has knowledge, but no one-year-old, any more than we could be mistaken in taking the word of a statute that eighteen-year-old can marry freely but seventeen-year-old cannot. (There is no more ontological ground for the distinction that may suit us to make in the former case than in the later.) Again, such a question as Are robots conscious? Calling for a decision on our part whether or not to treat robots as members of our linguistic community. All this is a piece with the insight brought into philosophy by Hegel (1770-1831), that the individual apart from his society is just another animal.

Willard van Orman Quine, the most influential American philosopher of the latter half of the 20th century, when after the wartime period in naval intelligence, punctuating the rest of his career with extensive foreign lecturing and travel. Quines early work was on mathematical logic, and issued in A System of Logistic (1934), Mathematical Logic (1940), and Methods of Logic (1950), whereby it was with the collection of papers from a Logical Point of View (1953) that his philosophical importance became widely recognized. Quines work dominated concern with problems of convention, meaning, and synonymy cemented by Word and Object (1960), in which the indeterminancy of radical translation first takes centre-stage. In this and many subsequent writings Quine takes a bleak view of the nature of the language with which we ascribe thoughts and beliefs to ourselves and others. These intentional idioms resist smooth incorporation into the scientific world view, and Quine responds with scepticism toward them, not quite endorsing eliminativism, but regarding them as second-rate idioms, unsuitable for describing strict and literal facts. For similar reasons he has consistently expressed suspicion of the logical and philosophical propriety of appeal to logical possibilities and possible worlds. The languages that are properly behaved and suitable for literal and true descriptions of the world as those of mathematics and science. The entities to which our best theories refer must be taken with full seriousness in our ontologies, although an empiricist. Quine thus supposes that the abstract objects of set theory are required by science, and therefore exist. In the theory of knowledge Quine associated with a holistic view of verification, conceiving of a body of knowledge in terms of a web touching experience at the periphery, but with each point connected by a network of relations to other points.

Quine is also known for the view that epistemology should be naturalized, or conducted in a scientific spirit, with the object of investigation being the relationship, in human beings, between the voice of experience and the outputs of belief. Although Quines approaches to the major problems of philosophy have been attacked as betraying undue scientism and sometimes behaviourism, the clarity of his vision and the scope of his writing made him the major focus of Anglo-American work of the past forty years in logic, semantics, and epistemology. As well as the works cited his writings cover The Ways of Paradox and Other Essays (1966), Ontological Relativity and Other Essays (1969), Philosophy of Logic (1970), The Roots of Reference (1974) and The Time of My Life: An Autobiography (1985).

Coherence is a major player in the theatre of knowledge. There are cogence theories of belief, truth and justification, as these are to combine themselves in the various ways to yield theories of knowledge coherence theories of belief are concerned with the content of beliefs. Consider a belief you now have, the beliefs that you are reading a page in a book, in so, that what makes that belief the belief that it is? What makes it the belief that you are reading a page in a book than the belief that you have a monster in the garden?

One answer is that the belief has a coherent place or role in a system of beliefs, perception or the having the perceptivity that has its influence on beliefs. As, you respond to sensory stimuli by believing that you are reading a page in a book than believing that you have a monster in the garden. Belief has an influence on action, or its belief is a desire to act, if belief will differentiate the differences between them, that its belief is a desire or if you were to believe that you are reading a page than if you believed in something about a monster. Sortal perceptivals hold accountably the perceptivity and action that are indeterminate to its content if its belief is the action as if stimulated by its inner and latent coherence in that of your belief, however. The same stimuli may produce various beliefs and various beliefs may produce the same action. The role that gives the belief the content it has is the role it plays within a network of relations to other beliefs, some latently causal than others that relate to the role in inference and implication. For example, I infer different things from believing that I am reading a page in a book than from any other belief, justly as I infer about other beliefs.

The information of perceptibility and the output of an action supplement the central role of the systematic relations the belief has to other belief, but the systematic relations give the belief the specific contentual representation it has. They are the fundamental source of the content of belief. That is how coherence comes in. A belief has the representational content by which it does because of the way in which it coheres within a system of beliefs (Rosenberg, 1988). We might distinguish weak coherence theories of the content of beliefs from stronger coherence theories. Weak coherence theories affirm that coherence is one determinant of the representation given that the contents are of belief. Strong coherence theories of the content of belief affirm that coherence is the sole determinant of the contentual representations of belief.

When we turn from belief to justification, we confront a similar group of coherence theories. What makes one belief justified and another not? Again, there is a distinction between weak and strong theoretic principles that govern its theory of coherence. Weak theories tell us that the ways in which a belief coheres with a background system of beliefs are one determinant of justification, other typical determinants being perception, memory, and intuitive projection, are, however strong theories, or dominant projections are in coherence to justification as solely a matter of how a belief coheres with a system of latent hierarchal beliefs. There is, nonetheless, another distinction that cuts across the distinction between weak and strong coherence theories between positive and negative coherence theory (Pollock, 1986). A positive coherence theory tells us that if a belief coheres with a background system of belief, then the belief is justifiable. A negative coherence theory tells us that if a belief fails to cohere with a background system of beliefs, then the belief is not justifiable. We might put this by saying that, according to the positivity of a coherence theory, coherence has the power to produce justification, while according to its being adhered by negativity, the coherence theory has only the power to nullify justification.

A strong coherence theory of justification is a formidable combination by which a positive and a negative theory tell us that a belief is justifiable if and only if it coheres with a background system of inter-connectivity of beliefs. Coherence theories of justification and knowledge have most often been rejected for being unable to deal with an accountable justification toward the perceptivity upon the projection of knowledge (Audi, 1988, and Pollock, 1986), and, therefore, considering a perceptual example that will serve as a kind of crucial test will be most appropriate. Suppose that a person, call her Julie, and works with a scientific instrumentation that has a gauging measure upon temperatures of liquids in a container. The gauge is marked in degrees, she looks at the gauge and sees that the reading is 105 degrees. What is she justifiably to believe, and why? Is she, for example, justified in believing that the liquid in the container is 105 degrees? Clearly, that depends on her background beliefs. A weak coherence theorist might argue that, though her belief that she sees the shape 105 is immediately justified as direct sensory evidence without appeal to a background system, the belief that the location in the container is 105 degrees results from coherence with a background system of latent beliefs that affirm to the shaping perceptivity that its 105 as visually read to be 105 degrees on the gauge that measures the temperature of the liquid in the container. This, nonetheless, of a weak coherence view that combines coherence with direct perceptivity as its evidence, in that the foundation of justification, is to account for the justification of our beliefs.

A strong coherence theory would go beyond the claim of the weak coherence theory to affirm that the justification of all beliefs, including the belief that one sees the shaping to sensory data that holds accountably of a measure of 105, or even the more cautious belief that one sees a shape, resulting from the perceptivals of coherence theory, in that it coheres with a background system. One may argue for this strong coherence theory in a number of different ways. One line or medium through which to appeal to the coherence theory of contentual representations. If the content of the perceptual belief results from the relations of the belief to other beliefs in a network system of beliefs, then one may notably argue that the justification of perceptivity, that the belief is a resultant from which its relation of the belief to other beliefs, in the network system of beliefs is in argument for the strong coherence theory is that without any assumptive reason that the coherence theory of contentual beliefs, in as much as the supposed causes that only produce the consequences we expect. Consider the very cautious belief that I see a shape. How may the justifications for that perceptual belief are an existent result that is characterized of its material coherence with a background system of beliefs? What might the background system tell us that would justify that belief? Our background system contains a simple and primal theory about our relationship to the world and surrounding surfaces that we perceive as it is or should be believed. To come to the specific point at issue, we believe that we can tell a shape when we see one, completely differentiated its form as perceived to sensory data, that we are to trust of ourselves about such simple matters as whether we see a shape before us or not, as in the acceptance of opening to nature the inter-connectivity between belief and the progression through which is acquired from past experiential conditions of application, and not beyond deception. Moreover, when Julie sees the believing desire to act upon what either coheres with a weak or strong coherence of theory, she shows that its belief, as a measurable quality or entity of 105, has the essence in as much as there is much more of a structured distinction of circumstance, which is not of those that are deceptive about whether she sees that shape or sincerely does not see of its shaping distinction, however. Visible light is good, and the numeral shapes are large, readily discernible and so forth. These are beliefs that Trust has single handedly authenticated reasons for justification. Her successive malignance to sensory access to data involved is justifiably a subsequent belief, in that with those beliefs, and so she is justified and creditable.

The philosophical; problems include discovering whether belief differs from other varieties of assent, such as acceptance discovering to what extent degrees of belief is possible, understanding the ways in which belief is controlled by rational and irrational factors, and discovering its links with other properties, such as the possession of conceptual or linguistic skills. This last set of problems includes the question of whether prelinguistic infants or animals are properly said to have beliefs.

Thus, we might think of coherence as inference to the best explanation based on a background system of beliefs, since we are not aware of such inferences for the most part, the inferences must be interpreted as unconscious inferences, as information processing, based on or finding the background system that proves most convincing of acquiring its act and used from the motivational force that its underlying and hidden desire are to do so. One might object to such an account on the grounds that not all justifiable inferences are self-explanatory, and more generally, the account of coherence may, at best, is ably successful to competitions that are based on background systems (BonJour, 1985, and Lehrer, 1990). The belief that one sees a shape competes with the claim that one does not, with the claim that one is deceived, and other sceptical objections. The background system of beliefs informs one that one is acceptingly trustworthy and enables one to meet the objections. A belief coheres with a background system just in case it enables one to meet the sceptical objections and in the way justifies one in the belief. This is a standard strong coherence theory of justification (Lehrer, 1990).

Illustrating the relationship between positive and negative coherence theories in terms of the standard coherence theory is easy. If some objection to a belief cannot be met in terms of the background system of beliefs of a person, then the person is not justified in that belief. So, to return to Julie, suppose that she has been told that a warning light has been installed on her gauge to tell her when it is not functioning properly and that when the red light is on, the gauge is malfunctioning. Suppose that when she sees the reading of 105, she also sees that the red light is on. Imagine, finally, that this is the first time the red light has been on, and, after years of working with the gauge, Julie, who has always placed her trust in the gauge, believes what the gauge tells her, that the liquid in the container is at 105 degrees. Though she believes what she reads is at 105 degrees is not a justified belief because it fails to cohere with her background belief that the gauge is malfunctioning. Thus, the negative coherence theory tells us that she is not justified in her belief about the temperature of the contents in the container. By contrast, when the red light is not illuminated and the background system of trust tells her that under such conditions that gauge is a trustworthy indicator of the temperature of the liquid in the container, then she is justified. The positive coherence theory tells us that she is justified in her belief because her belief coheres with her background system of trust tells she that under such conditions that gauge is a trustworthy indicator of the temperature of the liquid in the container, then she is justified. The positive coherence theory tells us that she is justified in her belief because her belief coheres with her background system continues as a trustworthy system.

The foregoing of coherence theories of justification have a common feature, namely, that they are what is called internalistic theories of justification what makes of such a view are the absence of any requirement that the person for whom the belief is justified have any cognitive access to the relation of reliability in question. Lacking such access, such a person will usually, have no reason for thinking the belief is true or likely to be true, but will, on such an account, are none the lesser to appear epistemologically justified in accepting it. Thus, such a view arguably marks a major break from the modern epistemological traditions, which identifies epistemic justification with having a reason, perhaps even a conclusive reason, for thinking that the belief is true. An epistemologist working within this tradition is likely to feel that the externalist, than offering a competing account of the same concept of epistemic justification with which the traditional epistemologist is concerned, has simply changed the subject.

They are theories affirming that coherence is a matter of internal relations between beliefs and that justification is a matter of coherence. If, then, justification is solely a matter of internal relations between beliefs, we are left with the possibility that the internal relations might fail to correspond with any external reality. How, one might object, can be to assume the including of interiority. A subjective notion of justification bridge the gap between mere true belief, which might be no more than a lucky guess, and knowledge, which must be grounded in some connection between internal subjective conditions and external objective realities?

The answer is that it cannot and that something more than justified true belief is required for knowledge. This result has, however, been established quite apart from consideration of coherence theories of justification. What are required maybes put by saying that the justification that one must be undefeated by errors in the background system of beliefs? Justification is undefeated by errors just in case any correction of such errors in the background system of belief would sustain the justification of the belief on the basis of the corrected system. So knowledge, on this sort of positivity is acclaimed by the coherence theory, which is the true belief that coheres with the background belief system and corrected versions of that system. In short, knowledge is true belief plus justification resulting from coherence and undefeated by error (Lehrer, 1990). The connection between internal subjective conditions of belief and external objectivity are from which realitys result from the required correctness of our beliefs about the relations between those conditions and realities. In the example of Julie, she believes that her internal subjectivity to conditions of sensory data in which the experience and perceptual beliefs are connected with the external objectivity in which reality is the temperature of the liquid in the container in a trustworthy manner. This background belief is essential to the justification of her belief that the temperature of the liquid in the container is 105 degrees, and the correctness of that background belief is essential to the justification remaining undefeated. So our background system of beliefs contains a simple theory about our relation to the external world that justifies certain of our beliefs that cohere with that system. For instance, such justification to convert to knowledge, that theory must be sufficiently free from error so that the coherence is sustained in corrected versions of our background system of beliefs. The correctness of the simple background theory provides the connection between the internal condition and external reality.

The coherence theory of truth arises naturally out of a problem raised by the coherence theory of justification. The problem is that anyone seeking to determine whether she has knowledge is confined to the search for coherence among her beliefs. The sensory experiences she has been deaf-mute until they are represented in the form of some perceptual belief. Beliefs are the engines that pull the train of justification. Nevertheless, what assurance do we have that our justification is based on true beliefs? What justification do we have that any of our justifications are undefeated? The fear that we might have none, that our beliefs might be the artifacts of some deceptive demon or scientist, leads to the quest to reduce truth to some form, perhaps an idealized form, of justification (Rescher, 1973, and Rosenberg, 1980). That would close the threatening sceptical gap between justification and truth. Suppose that a belief is true if and only if it is justifiable of some person. For such a person there would be no gap between justification and truth or between justification and undefeated justification. Truth would be coherence with some ideal background system of beliefs, perhaps one expressing a consensus among systems or some consensus among belief systems or some convergence toward a consensus. Such a view is theoretically attractive for the reduction it promises, but it appears open to profound objectification. One is that there is a consensus that we can all be wrong about at least some matters, for example, about the origins of the universe. If there is a consensus that we can all be wrong about something, then the consensual belief system rejects the equation of truth with the consensus. Consequently, the equation of truth with coherence with a consensual belief system is itself incoherent.

Coherence theories of the content of our beliefs and the justification of our beliefs themselves cohere with our background systems but coherence theories of truth do not. A defender of Coherentism must accept the logical gap between justified belief and truth, but may believe that our capacities suffice to close the gap to yield knowledge. That view is, at any rate, a coherent one.

What makes a belief justified and what makes a true belief knowledge? Thinking that whether a belief deserves one of these appraisals is natural depends on what causal subject to have the belief. In recent decades a number of epistemologists have pursed this plausible idea with a variety of specific proposals. Some causal theories of knowledge have it that a true belief that ‘p’ is knowledge just in case it has the right causal connection to the fact that ‘p’. Such a criterion can be applied only to cases where the fact that p is a sort that can enter causal relations, this seems to exclude mathematically and other necessary facts and perhaps any fact expressed by a universal generalization, and proponents of this sort of criterion have usually of this sort of criterion have usually supposed that it is limited to perceptual knowledge of particular facts about the subjects environment.

For example, Armstrong (1973), proposed that a belief of form This (perceived) object is ‘F’ is (non-inferential) knowledge if and only if the belief is a completely reliable sign that the perceived object is ‘F’, that is, the fact that the object is ‘F’ contributed to causing the belief and its doing so depended on properties of the believer such that the laws of nature dictated that, for any subject ‘P’ is to occur, and so thus a perceived object of ‘y’, if ‘P’ undergoing those properties are for us to believe that ‘y’ is ‘F’, then ‘y’ is ‘F’. (Dretske (1981) offers a similar account, in terms of the beliefs being caused by a signal received by the perceiver that carries the information that the object is ‘F’.

This sort of condition fails, however, to be sufficient for non-inferential perceptual knowledge because it is compatible with the beliefs being unjustified, and an unjustifiable belief cannot be knowledge. For example, suppose that your mechanisms for colour perception are working well, but you have been given good reason to think otherwise, to think, say, that the substantive primary colours that are perceivable, that things look chartreuse to you and chartreuse things look magenta. If you fail to heed these reasons you have for thinking that your colour perception or sensory data is a way. Believing in a thing, which looks to blooms of vividness that you are to believe of its chartreuse, your belief will fail to be justified and will therefore fail to be knowledge, even though it is caused by the things being magenta in such a way as to be a completely reliable sign, or to carry the information, in that the thing is one of the subtractive primary colour, in fact of a purplish-red orientation.

One could fend off this sort of counterexample by simply adding to the causal condition the requirement that the belief be justified, buy this enriched condition would still be insufficient. Suppose, for example, that in nearly all people, but not in you, as it happens, causes the aforementioned aberration in colour perceptions. The experimenter tells you that you have taken such a drug but then says, no, hold off a minute, the pill you took was just a placebo, suppose further, that this last thing the experimenter tells you is false. Her telling you that it was a false statement, and, again, telling you this gives you justification for believing of a thing that looks a subtractive primary colour to you that it is a sensorial primary colour, in that the fact you were to expect that the experimenters last statements were false, making it the case that your true belief is not knowledgeably correct, thought as though to satisfy its causal condition.

Goldman (1986) has proposed an importantly different causal criterion namely, that a true belief is knowledge, if it is produced by a type of process that is globally and locally reliable. Causing true beliefs is sufficiently high is globally reliable if its propensity. Local reliability has to do with whether the process would have produced a similar but false belief in certain counterfactual situations alternative to the actual situation. This way of marking off true beliefs that are knowledge does not require the fact believed to be casually related to the belief, and so it could in principle apply to knowledge of any kind of truth.

Goldman requires that global reliability of the belief-producing process for the justification of a belief, he requires it also for knowledge because justification is required for knowledge, in what requires for knowledge but does not require for justification, which is locally reliable. His idea is that a justified true belief is knowledge if the type of process that produced it would not have produced it in any relevant counterfactual situation in which it is false. The relevant alternative account of knowledge can be motivated by noting that other concepts exhibit the same logical structure. Two examples of this are the concept flat and the concept empty (Dretske, 1981). Both appear to be absolute concepts-A space is empty only if it does not contain anything and a surface is flat only if it does not have any bumps. However, the absolute character of these concepts is relative to a standard. In the case of flat, there is a standard for what counts as a bump and in the case of empty, there is a standard for what counts as a thing. To be flat is to be free of any relevant bumps and to be empty is to be devoid of all relevant things.

Nevertheless, the human mind abhors a vacuum. When an explicit, coherent world-view is absent, it functions on the basis of a tactic one. A tactic world-view is not subject to a critical evaluation, and it can easily harbour inconsistencies. Indeed, our tactic set of beliefs about the nature of reality is made of contradictory bits and pieces. The dominant component is a leftover from another period, the Newtonian clock universe still lingers as we cling to this old and tired model because we know of nothing else that can take its place. Our condition is the condition of a culture that is in the throes of a paradigm shift. A major paradigm shift is complex and difficult because a paradigm holds us captive: We see reality through it, as through coloured glasses, but we do not know that, we are convinced that we see reality as it is. Hence the appearance of a new and different paradigm is often incomprehensible. To someone raised believing that the Earth is flat, the suggestion that the Earth is spherical would seem preposterous: If the Earth were spherical, would not the poor antipodes fall down into the sky?

Yet, as we now face a new millennium, we are forced to face this challenge. The fate of the planet is in question, and it was brought to its present precarious condition largely because of our trust in the Newtonian paradigm. As Newtonian world-view has to go, and, if one looks carefully, the main feature of the new, emergent paradigm can be discerned. The search for these features is what was the influence of a fading paradigm. All paradigms include subterranean realms of tactic assumptions, the influence of which outlasts the adherence to the paradigm itself.

The first line of exploration suggests the weird aspects of the quantum theory, with fertile grounds for our feeling of which should disappear in inconsistencies with the prevailing world-view. This feeling is in replacing by the new one, i.e., if one believes that the Earth is flat, the story of Magellans travels is quite puzzling: How travelling due west is possible for a ship and, without changing direct. Arrive at its place of departure? Obviously, when the flat-Earth paradigm is replaced by the belief that Earth is spherical, the puzzle is instantly resolved.

The founders of Relativity and quantum mechanics were deeply engaging but incomplete, in that none of them attempted to construct a philosophical system, however, that the mystery at the heart of the quantum theory called for a revolution in philosophical outlooks. During which time, the 1920s, when quantum mechanics reached maturity, began the construction of a full-blooded philosophical system that was based not only on science but on nonscientific modes of knowledge as well. As, the fading influence drawn upon the paradigm goes well beyond its explicit claim. We believe, as the scenists and philosophers did, that when we wish to find out the truth about the universe, nonscientific nodes of processing human experiences can be ignored, poetry, literature, art, music are all wonderful, but, in relation to the quest for knowledge of the universe, they are irrelevant. Yet, it was Alfred North Whitehead who pointed out the fallacy of this speculative assumption. In this, as well as in other aspects of thinking of some reality in which are the building blocks of reality are not material atoms but throbs of experience. Whitehead formulated his system in the late 1920s, and yet, as far as I know, the founders of quantum mechanics were unaware of it. It was not until 1963 that J. M. Burgers pointed out that its philosophy accounts very well for the main features of the quanta, especially the weird ones, enabling as in some aspects of reality is higher or deeper than others, and if so, what is the structure of such hierarchical divisions? What of our place in the universe? Finally, what is the relationship between the great aspiration within the lost realms of nature? An attempt to endow us with a cosmological meaning in such a universe seems totally absurd, and, yet, this very universe is just a paradigm, not the truth. When you reach its end, you may be willing to join the alternate view as accorded to which, surprisingly bestow us with what is restored, although in a post-postmodern context.

The philosophical implications of quantum mechanics have been regulated by subjective matters, as to emphasis the connections between what I believe, in that investigations of such interconnectivity are anticipatorially the hesitations that are an exclusion held within the western traditions, however, the philosophical thinking, from Plato to Platinous had in some aspects of interpretational presentation of her expression of a consensus of the physical community. Other aspects are shared by some and objected to (sometimes vehemently) by others. Still other aspects express my own views and convictions, as turning about to be more difficult that anticipated, discovering that a conversational mode would be helpful, but, their conversations with each other and with me in hoping that all will be not only illuminating but finding to its read may approve in them, whose dreams are dreams among others than themselves.

These examples make it seem likely that, if there is a criterion for what makes an alternative situation relevant that will save Goldmans claim about reliability and the acceptance of knowledge, it will not be simple.

The interesting thesis that counts as a causal theory of justification, in the meaning of causal theory intend of the belief that is justified just in case it was produced by a type of process that is globally reliable, that is, its propensity to produce true beliefs-that can be defined to a favourably bringing close together the proportion of the belief and to what it produces, or would produce where it used as much as opportunity allows, that is true-is sufficiently that a belief acquires favourable epistemic status by having some kind of reliable linkage to the truth. Variations of this view have been advanced for both knowledge and justified belief. The first formulations of are reliably in its account of knowing appeared in if not by F.P. Ramsey (1903-30) who made important contributions to mathematical logic, probability theory, the philosophy of science and economics. Instead of saying that quarks have such-and-such properties, the Ramsey sentence says that it is moderately something that has those properties. If the process is repeated for all of the theoretical terms, the sentence gives the topic-neutral structure of the theory, but removes any implication that we know what the term so covered have as a meaning. It leaves open the possibility of identifying the theoretical item with whatever, but it is that best fits the description provided, thus, substituting the term by a variable, and existentially qualifying into the result. Ramsey was one of the first thinkers to accept a redundancy theory of truth, which he combined its radical views of the function of many kinds of the proposition. Neither generalizations, nor causal propositions, not those treating probabilities or ethics, described facts, but each has a different specific function in our intellectual commentators on the early works of Wittgenstein, and his continuing friendship with the latter liked to Wittgensteins return to Cambridge and to philosophy in 1929.

The most sustained and influential application of these ideas were in the philosophy of mind, or brain, as Ludwig Wittgenstein (1889-1951) whom Ramsey persuaded that remained work for him to do, the way that is most undoubtedly was of an appealingly charismatic figure in a 20th-century philosophy, living and writing with a power and intensity that frequently overwhelmed his contemporaries and readers, the early period is centred on the picture theory of meaning according to which sentence represents a state of affairs by being a kind of picture or model of it. Containing the elements that were in corresponding to those of the state of affairs and structure or form that mirrors that a structure of the state of affairs that it represents. All logic complexity is reduced to that of the propositional calculus, and all propositions are truth-function of atomic or basic propositions.

In the later period the emphasis shifts dramatically to the actions of people and the role linguistic activities play in their lives. Thus, whereas in the Tractatus language is placed in a static, formal relationship with the world, in the later work Wittgenstein emphasis its use in the context of standardized social activities of ordering, advising, requesting, measuring, counting, excising concerns for each other, and so on. These different activities are thought of as so many language games that together make or a form of life. Philosophy typically ignores this diversity, and in generalizing and abstracting distorts the real nature of its subject-matter. In addition to the Tractatus and the!investigations collections of Wittgensteins work published posthumously include Remarks on the Foundations of Mathematics (1956), Notebooks (1914-1916) (1961), Pholosophische Bemerkungen (1964), Zettel (1967, and On Certainty (1969).

Clearly, there are many forms of Reliabilism. Just as there are many forms of Foundationalism and coherence. How is Reliabilism related to these other two theories of justification? It is usually regarded as a rival. This is aptly so, in as far as Foundationalism and Coherentism traditionally focussed on purely evidential relations than psychological processes, but Reliabilism might also be offered as a deeper-level theory, subsuming some of the precepts of either Foundationalism or Coherentism. Foundationalism says that there are basic beliefs, which acquire justification without dependence on inference, Reliabilism might rationalize this indicating that the basic beliefs are formed by reliable non-inferential processes. Coherence stresses the primary of systematicity in all doxastic decision-making. Reliabilism might rationalize this by pointing to increases in reliability that accrue from systematicity consequently, Reliabilism could complement Foundationalism and coherence than completed with them.

These examples make it seem likely that, if there is a criterion for what makes an alternate situation relevant that will save Goldmans claim about local reliability and knowledge. Will did not be simple. The interesting thesis that counts as a causal theory of justification, in the making of causal theory intended for the belief as it is justified in case it was produced by a type of process that is globally reliable, that is, its propensity to produce true beliefs that can be defined, to a well-thought-of approximation, as the proportion of the beliefs it produces, or would produce where it used as much as opportunity allows, that is true is sufficiently relializable. Variations of this view have been advanced for both knowledge and justified belief, its first formulation of a reliability account of knowing appeared in the notation from F.P.Ramsey (1903-30). The theory of probability, he was the first to show how a personalists theory could be developed, based on a precise behavioural notion of preference and expectation. In the philosophy of language. Much of Ramseys work was directed at saving classical mathematics from intuitionism, or what he called the Bolshevik menace of Brouwer and Weyl. In the theory of probability he was the first to show how a personalists theory could be developed, based on precise behavioural notation of preference and expectation. In the philosophy of language, Ramsey was one of the first thankers, which he combined with radical views of the function of many kinds of a proposition. Neither generalizations, nor causal propositions, nor those treating probability or ethics, describe facts, but each has a different specific function in our intellectual economy. Ramsey was one of the earliest commentators on the early work of Wittgenstein, and his continuing friendship with Wittgenstein.

Ramseys sentence theory is the sentence generated by taking all the sentences affirmed in a scientific theory that use some term, e.g., quark. Replacing the term by a variable, and existentially quantifying into the result. Instead of saying that quarks have such-and-such properties, the Ramsey sentence says that there is something that has those properties. If the process is repeated for all of a group of the theoretical terms, the sentence gives the topic-neutral structure of the theory, but removes any implication that we know what the term so treated characterized. It leaves open the possibility of identifying the theoretical item with whatever, and it is that best fits the description provided. Virtually, all theories of knowledge. Of course, share an externalist component in requiring truth as a condition for known in. Reliabilism goes further, however, in trying to capture additional conditions for knowledge by ways of a nomic, counterfactual or other such external relations between belief and truth. Closely allied to the nomic sufficiency account of knowledge, primarily due to Dretshe (1971, 1981), A.I. Goldman (1976, 1986) and R. Nozick (1981). The core of this approach is that ‘X’s’ belief that ‘p’ qualifies as knowledge just in case ‘X’ believes ‘p’, because of reasons that would not obtain unless ps being true, or because of a process or method that would not yield belief in ‘p’ if ‘p’ were not true. For example, ‘X’ would not have its current reasons for believing there is a telephone before it. Perhaps, would it not come to believe that this in the way it suits the purpose, thus, there is a differentiable fact of a reliable guarantor that the beliefs bing true. A stouthearted and valiant counterfactual approach says that ‘X’ knows that p only if there is no relevant alternative situation in which ‘p’ is false but ‘X’ would still believe that a proposition ‘p’; must be sufficient to eliminate all the alternatives to ‘p’ where an alternative to a proposition ‘p’ is a proposition incompatible with ‘p’? That in, ones justification or evidence for ‘p’ must be sufficient for one to know that every alternative to ‘p’ is false. This element of our evolving thinking, about which knowledge is exploited by sceptical arguments. These arguments call our attentions to alternatives that our evidence sustains itself with no elimination. The sceptic inquires to how we know that we are not seeing a cleverly disguised mule. While we do have some evidence against the likelihood of such as deception, intuitively knowing that we are not so deceived is not strong enough for us. By pointing out alternate but hidden points of nature, in that we cannot eliminate, as well as others with more general application, as dreams, hallucinations, etc., the sceptic appears to show that every alternative is seldom. If ever, satisfied.

This conclusion conflicts with another strand in our thinking about knowledge, in that we know many things. Thus, there is a tension in our ordinary thinking about knowledge ~. We believe that knowledge is, in the sense indicated, an absolute concept and yet, we also believe that there are many instances of that concept.

If one finds absoluteness to be too central a component of our concept of knowledge to be relinquished, one could argue from the absolute character of knowledge to a sceptical conclusion (Unger, 1975). Most philosophers, however, have taken the other course, choosing to respond to the conflict by giving up, perhaps reluctantly, the absolute criterion. This latter response holds as sacrosanct our commonsense belief that we know many things (Pollock, 1979 and Chisholm, 1977). Each approach is subject to the criticism that it preserves one aspect of our ordinary thinking about knowledge at the expense of denying another. The theory of relevant alternatives can be viewed as an attempt to provide a more satisfactory response to this tension in our thinking about knowledge. It attempts to characterize knowledge in a way that preserves both our belief that knowledge is an absolute concept and our belief that we have knowledge.

Just as space, the classical questions include: Is space real? Is it some kind of mental construct or artefact of our ways of perceiving and thinking? Is it substantival or purely? relational? According to substantivalism, space is an objective thing consisting of points or regions at which, or in which, things are located. Opposed to this is relationalism, according to which the only things that are real about space are the spatial (and temporal) relations between physical objects. Substantivalism was advocated by Clarke speaking for Newton, and relationalism by Leibniz, in their famous correspondence, and the debate continues today. There is also an issue whether the measure of space and time are objective, or whether an element of convention enters them. Whereby, the influential analysis of David Lewis suggests that a regularity hold as a matter of convention when it solves a problem of coordinating in a group. This means that it is to the benefit of each member to conform to the regularity, providing the others do so. Any number of solutions to such a problem may exist, for example, it is to the advantages of each of us to drive on the same side of the road as others, but indifferent whether we all drive o the right or the left. One solution or another may emerge for a variety of reasons. It is notable that on this account convections may arise naturally; they do not have to be the result of specific agreement. This frees the notion for use in thinking about such things as the origin of language or of political society.

The finding to a theory that magnifies the role of decisions, or free selection from among equally possible alternatives, in order to show that what appears to be objective or fixed by nature is in fact an artefact of human convention, similar to conventions of etiquette, or grammar, or law. Thus one might suppose that moral rules owe more to social convention than to anything imposed from outside, or hat supposedly inexorable necessities are in fact the shadow of our linguistic conventions. The disadvantage of conventionalism is that it must show that alternative, equally workable e conventions could have been adopted, and it is often easy to believe that, for example, if we hold that some ethical norm such as respect for promises or property is conventional, we ought to be able to show that human needs would have been equally well satisfied by a system involving a different norm, and this may be hard to establish.

A convention also suggested by Paul Grice (1913-88) directing participants in conversation to pay heed to an accepted purpose or direction of the exchange. Contributions made without paying this attention are liable to be rejected for other reasons than straightforward falsity: Something effectually unhelpful or inappropriate may meet with puzzlement or rejection. We can thus never infer fro the fact that it would be inappropriate to say something in some circumstance that what would be aid, were we to say it, would be false. This inference was frequently and in ordinary language philosophy, it being argued, for example, that since we do not normally say there sees to be a barn there when there is unmistakably a barn there, it is false that on such occasions there seems to be a barn there.

There are two main views on the nature of theories. According to the received view theories are partially interpreted axiomatic systems, according to the semantic view, a theory is a collection of models (Suppe, 1974). However, a natural language comes ready interpreted, and the semantic problem is no that of the specification but of understanding the relationship between terms of various categories (names, descriptions, predicates, adverbs . . .) and their meanings. An influential proposal is that this relationship is best understood by attempting to provide a truth definition for the language, which will involve giving terms and structure of different kinds have on the truth-condition of sentences containing them.

The axiomatic method . . . as, . . . a proposition lid down as one from which we may begin, an assertion that we have taken as fundamental, at least for the branch of enquiry in hand. The axiomatic method is that of defining as a set of such propositions, and the proof procedures or finding of how a proof ever gets started. Suppose I have as premises (1) p and (2) p ! q. Can I infer q? Only, it seems, if I am sure of, (3) (p & p !q) !q. Can I then infer q? Only, it seems, if I am sure that (4) (p & p ! q) ! q) ! q. For each new axiom (N) I need a further axiom (N + 1) telling me that the set so far implies q, and the regress never stops. The usual solution is to treat a system as containing not only axioms, but also rules of reference, allowing movement fro the axiom. The rule modus ponens allow us to pass from the first two premises to q. Charles Dodgson Lutwidge (1832-98) better known as Lewis Carrolls puzzle shows that it is essential to distinguish two theoretical categories, although there may be choice about which to put in which category.

This type of theory (axiomatic) usually emerges as a body of (supposes) truths that are not nearly organized, making the theory difficult to survey or study a whole. The axiomatic method is an idea for organizing a theory (Hilbert 1970): one tries to select from among the supposed truths a small number from which all others can be seen to be deductively inferable. This makes the theory rather more tractable since, in a sense, all the truths are contained in those few. In a theory so organized, the few truths from which all others are deductively inferred are called axioms. In that, just as algebraic and differential equations, which were used to study mathematical and physical processes, could themselves be made mathematical objects, so axiomatic theories, like algebraic and differential equations, which are means of representing physical processes and mathematical structures, could be made objects of mathematical investigation.

In the traditional (as in Leibniz, 1704), many philosophers had the conviction that all truths, or all truths about a particular domain, followed from a few principles. These principles were taken to be either metaphysically prior or epistemologically prior or in the fist sense, they were taken to be entities of such a nature that what exists is caused by them. When the principles were taken as epistemologically prior, that is, as axioms, either they were taken to be epistemologically privileged, e.g., self-evident, not needing to be demonstrated or (again, inclusive or) to be such that all truths do follow from them (by deductive inferences). Gödel (1984) showed that treating axiomatic theories as themselves mathematical objects, that mathematics, and even a small part of mathematics, elementary number theory, could not be axiomatized, that, more precisely, any class of axioms that in such that we could effectively decide, of any proposition, whether or not it was in the class, would be too small to capture all of the truths.

Gödel proved in 1929 that first-order predicate calculus is complete: any formula that is true under every interpretation is a theorem of the calculus: The propositional calculus or logical calculus whose expressions are letter present sentences or propositions, and constants representing operations on those propositions to produce others of higher complexity. The operations include conjunction, disjunction, material implication and negation (although these need not be primitive). Propositional logic was partially anticipated by the Stoics but researched maturity only with the work of Frége, Russell, and Wittgenstein.

The concept introduced by Frége of a function taking a number of names as arguments, and delivering one proposition as the value. The idea is that ‘P’ loves ‘y’ is a propositional function, which yields the proposition John loves Mary from those two arguments (in that order). A propositional function is therefore roughly equivalent to a property or relation. In Principia Mathematica, Russell and Whitehead take propositional functions to be the fundamental function, since the theory of descriptions could be taken as showing that other expressions denoting functions are incomplete symbols.

Keeping in mind, the two classical truth-values that a statement, proposition, or sentence can take. It is supposed in classical (two-valued) logic, that each statement has one of these values, and none has both. A statement is then false if and only if it is not true. The basis of this scheme is that to each statement there corresponds a determinate truth condition, or way the world must be for it to be true, and otherwise false. Statements may be felicitous or infelicitous in other dimensions, polite, misleading, apposite, witty, etc., but truth is the central normative governing assertion. Considerations of vagueness may introduce greys into black-and-white scheme. For the issue of whether falsity is the only way of failing to be true.

Formally, it is nonetheless, that any suppressed premise or background framework of thought necessary to make an argument valid, or a position tenable. More formally, a presupposition has been defined as a proposition whose truth is necessary for either the truth or the falsity of another statement. Thus, if p presupposes q, q must be true for p to be either true or false. In the theory of knowledge of Robin George Collingwood (1889-1943), any propositions capable of truth or falsity stand on a bed of absolute presuppositions which are not properly capable of truth or falsity, since a system of thought will contain no way of approaching such a question. It was suggested by Peter Strawson, 1919-in opposition to Russells theory of definite descriptions, that there exists a King of France is a presupposition of the King of France is bald, the latter being neither true, nor false, if there is no King of France. It is, however, a little unclear weather the idea is that no statement at all is made in such a case, or whether a statement is made, but fails of being either true or false. The former option preserves classical logic, since we can still say that every statement is either true or false, but the latter does not, since in classical logic the law of bivalence holds, and ensures that nothing at all is presupposed for any proposition to be true or false. The introduction of presupposition therefore means that either a third truth-value is found, intermediate between truth and falsity, or that classical logic is preserved, but it is impossible to tell whether a particular sentence expresses a proposition that is a candidate for truth ad falsity, without knowing more than the formation rules of the language. Each suggestion carries costs, and there is some consensus that at least where definite descriptions are involved, examples like the one given are equally well handed by regarding the overall sentence false when the existence claim fails.

A proposition may be true or false it be said to take the truth-value true, and if the latter the truth-value false. The idea behind the term is the analogy between assigning a propositional variable one or other of these values, as a formula of the propositional calculus, and assigning an object as the value of many other variable. Logics with intermediate values are called many-valued logics. Then, a truth-function of a number of propositions or sentences is a function of them that has a definite truth-value, depend only on the truth-values of the constituents. Thus (p & q) is a combination whose truth-value is true when ‘p’ is true and ‘q’ is true, and false otherwise,’¬ p’ is a truth-function of ‘p’, false when ‘p’ is true and true when ‘p’ is false. The way in which the value of the whole is determined by the combinations of values of constituents is presented in a truth table.

In whatever manner, truths of fact cannot be reduced to any identity and our only way of knowing them is empirically, by reference to the facts of the empirical world.

A proposition is knowable deductively if it can be known without experience of the specific course of events in the actual world. It may, however, be allowed that some experience is required to acquire the concepts involved in an deductive proposition. Some thing is knowable only empirical if it can be known deductively. The distinction given one of the fundamental problem areas of epistemology. The category of deductive propositions is highly controversial, since it is not clear how pure thought, unaided by experience, can give rise to any knowledge at all, and it has always been a concern of empiricism to deny that it can. The two great areas in which it seems to be so are logic and mathematics, so empiricists have commonly tried to show either that these are not areas of real, substantive knowledge, or that in spite of appearances their knowledge that we have in these areas is actually dependent on experience. The former line tries to show sense trivial or analytic, or matters of notation conventions of language. The latter approach is particularly y associated with Quine, who denies any significant slit between propositions traditionally thought of as speculatively, and other deeply entrenched beliefs that occur in our overall view of the world.

Another contested category is that of speculative concepts, supposed to be concepts that cannot be derived from experience, bu t which are presupposed in any mode of thought about the world, time, substance, causation, number, and self are candidates. The need for such concept s, and the nature of the substantive a prior I knowledge to which they give rise, is the central concern of Kant s Critique of Pure Reason.

Likewise, since their denial does not involve a contradiction, there is merely contingent: Their could have been in other ways a hold of the actual world, but not every possible one. Some examples are Caesar crossed the Rubicon and Leibniz was born in Leipzig, as well as propositions expressing correct scientific generalizations. In Leibnizs view truths of fact rest on the principle of sufficient reason, which is a reason why it is so. This reason is that the actual world (by which he means the total collection of things past, present and future) is better than any other possible world and therefore created by God. The foundation of his thought is the conviction that to each individual there corresponds a complete notion, knowable only to God, from which is deducible all the properties possessed by the individual at each moment in its history. It is contingent that God actualizes te individual that meets such a concept, but his doing so is explicable by the principle of sufficient reason, whereby God had to actualize just that possibility in order for this to be the best of all possible worlds. This thesis is subsequently lampooned by Voltaire (1694-1778), in whom of which was prepared to take refuge in ignorance, as the nature of the soul, or the way to reconcile evil with divine providence.

In defending the principle of sufficient reason sometimes described as the principle that nothing can be so without there being a reason why it is so. But the reason has to be of a particularly potent kind: eventually it has to ground contingent facts in necessities, and in particular in the reason an omnipotent and perfect being would have for actualizing one possibility than another. Among the consequences of the principle is Leibnizs relational doctrine of space, since if space were an infinite box there could be no reason for the world to be at one point in rather than another, and God placing it at any point violate the principle. In Abelards (1079-1142), as in Leibniz, the principle eventually forces te recognition that the actual world is the best of all possibilities, since anything else would be inconsistent with the creative power that actualizes possibilities.

If truth consists in concept containment, then it seems that all truths are analytic and hence necessary. If they are all necessary, surely they are all truths of reason. In that not every truth can be reduced to an identity in a finite number of steps; in some instances revealing the connection between subject and predicate concepts would require an infinite analysis, while this may entail that we cannot prove such proposition as a prior, it does not appear to show that proposition could have ben false. Intuitively, it seems a better ground for supposing that it is a necessary truth of a special sort. A related question arises from the idea that truths of fact depend on Gods decision to create the best world: If it is part of the concept of this world that it is best, how could its existence be other than necessary? An accountable and responsively answered explanation would be so, that any relational question that brakes the norm lay eyes on its existence in the manner other than hypothetical necessities, i.e., it follows from Gods decision to create the world, but God had the power to create this world, but God is necessary, so how could he have decided to do anything else? Leibniz says much more about these matters, but it is not clear whether he offers any satisfactory solutions.

The view that the terms in which we think of some area is sufficiently infected with error for it to be better to abandon them than to continue to try to give coherent theories of their use. Eliminativism should be distinguished from scepticism that claims that we cannot know the truth about some area; eliminativism claims rather that there is no truth there to be known, in the terms that we currently think. An eliminativist about theology simply counsels abandoning the terms or discourse of theology, and that will include abandoning worries about the extent of theological knowledge.

Eliminativists in the philosophy of mind counsel abandoning the whole network of terms mind, consciousness, self, qualia that usher in the problems of mind and body. Sometimes the argument for doing this is that we should wait for a supposed future understanding of ourselves, based on cognitive science and better than any our current mental descriptions provide, sometimes it is supposed that physicalism shows that no mental description of ourselves could possibly be true.

Sceptical tendencies emerged in the 14th-century writings of Nicholas of Autrecourt. His criticisms of any certainty beyond the immediate deliverance of the senses and basic logic, and in particular of any knowledge of either intellectual or material substances, anticipate the later scepticism of Balye and Hume. The; latter distinguishes between Pyrrhonistic and excessive scepticism, which he regarded as unlivable, and the more mitigated scepticism that accepts every day or commonsense beliefs (not as the delivery of reason, but as due more to custom and habit), but is duly wary of the power of reason to give us much more. Mitigated scepticism is thus closer to the attitude fostered by ancient scepticism from Pyrrho through to Sexus Empiricus. Although the phrase Cartesian scepticism is sometimes used, Descartes himself was not a sceptic, but in the method of doubt, uses a sceptical scenario in order to begin the process of finding a secure mark of knowledge. Descartes himself trusts a category of clear and distinct ideas, not far removed from the phantasia kataleptiké of the Stoics.

Scepticism should not be confused with relativism, which is a doctrine about the nature of truth, and may be motivated by trying to avoid scepticism. Nor is it identical with eliminativism, which counsels abandoning an area of thought altogether, not because we cannot know the truth, but because there are no truths capable of being framed in the terms we use.

Descartes theory of knowledge starts with the quest for certainty, for an indubitable starting-point or foundation on the basis alone of which progress is possible. This is eventually found in the celebrated Cogito ergo sum: I think therefore I am. By locating the point of certainty in my own awareness of my own self, Descartes gives a first-person twist to the theory of knowledge that dominated them following centuries in spite of various counter-attacks on behalf of social and public starting-points. The metaphysics associated with this priority is the famous Cartesian dualism, or separation of mind and matter into two different but interacting substances, Descartes rigorously and rightly sees that it takes divine dispensation to certify any relationship between the two realms thus divided, and to prove the reliability of the senses invokes a clear and distinct perception of highly dubious proofs of the existence of a benevolent deity. This has not met general acceptance: as Hume drily puts it, to have recourse to the veracity of the supreme Being, in order to prove the veracity of our senses, is surely making a very unexpected circuit.

In his own time Descartes conception of the entirely separate substance of the mind was recognized to give rise to insoluble problems of the nature of the causal connection between the two. It also gives rise to the problem, insoluble in its own terms, of other minds. Descartes notorious denial that non-human animals are conscious is a stark illustration of the problem. In his conception of matter Descartes also gives preference to rational cogitation over anything derived from the senses. Since we can conceive of the matter of a ball of wax surviving changes to its sensible qualities, matter is not an empirical concept, but eventually an entirely geometrical one, with extension and motion as its only physical nature. Descartes thought, as reflected in Leibniz, that the qualities of sense experience have no resemblance to qualities of things, so that knowledge of the external world is essentially knowledge of structure rather than of filling. On this basis Descartes erects a remarkable physics. Since matter is in effect the same as extension there can be no empty space or void, since there is no empty space motion is not a question of occupying previously empty space, but is to be thought of in terms of vortices (like the motion of a liquid).

Although the structure of Descartes epistemology, theory of mind, and theory of matter have ben rejected many times, their relentless exposure of the hardest issues, their exemplary clarity, and even their initial plausibility, all contrive to make him the central point of reference for modern philosophy.

The self conceived as Descartes presents it in the first two Meditations: aware only of its own thoughts, and capable of disembodied existence, neither situated in a space nor surrounded by others. This is the pure self of I-ness that we are tempted to imagine as a simple unique thing that make up our essential identity. Descartes view that he could keep hold of this nugget while doubting everything else is criticized by Lichtenberg and Kant, and most subsequent philosophers of mind.

Descartes holds that we do not have any knowledge of any empirical proposition about anything beyond the contents of our own minds. The reason, roughly put, is that there is a legitimate doubt about all such propositions because there is no way to deny justifiably that our senses are being stimulated by some cause (an evil spirit, for example) which is radically different from the objects that we normally think affect our senses.

He also points out, that the senses (sight, hearing, touch, etc., are often unreliable, and it is prudent never to trust entirely those who have deceived us even once, he cited such instances as the straight stick that looks ben t in water, and the square tower that looks round from a distance. This argument of illusion, has not, on the whole, impressed commentators, and some of Descartes contemporaries pointing out that since such errors become known as a result of further sensory information, it cannot be right to cast wholesale doubt on the evidence of the senses. But Descartes regarded the argument from illusion as only the first stage in a softening up process which would lead the mind away from the senses. He admits that there are some cases of sense-base belief about which doubt would be insane, e.g., the belief that I am sitting here by the fire, wearing a winter dressing gown.

Descartes was to realize that there was nothing in this view of nature that could explain or provide a foundation for the mental, or from direct experience as distinctly human. In a mechanistic universe, he said, there is no privileged place or function for mind, and the separation between mind and matter is absolute. Descartes was also convinced, that the immaterial essences that gave form and structure to this universe were coded in geometrical and mathematical ideas, and this insight led him to invent algebraic geometry.

A scientific understanding of these ideas could be derived, said Descartes, with the aid of precise deduction, and he also claimed that the contours of physical reality could be laid out in three-dimensional coordinates. Following the publication of Newtons Principia Mathematica in 1687, reductionism and mathematical modelling became the most powerful tools of modern science. And the dream that the entire physical world could be known and mastered through the extension and refinement of mathematical theory became the central feature and guiding principle of scientific knowledge.

Having to its recourse of knowledge, its cental questions include the origin of knowledge, the place of experience in generating knowledge, and the place of reason in doing so, the relationship between knowledge and certainty, and between knowledge and the impossibility of error, the possibility of universal scepticism, and the changing forms of knowledge that arise from new conceptualizations of the world. All of these issues link with other central concerns of philosophy, such as the nature of truth and the natures of experience and meaning.

Foundationalism was associated with the ancient Stoics, and in the modern era with Descartes (1596-1650). Who discovered his foundations in the clear and distinct ideas of reason? Its main opponent is Coherentism, or the view that a body of propositions mas be known without a foundation in certainty, but by their interlocking strength, than as a crossword puzzle may be known to have been solved correctly even if each answer, taken individually, admits of uncertainty. Difficulties at this point led the logical passivists to abandon the notion of an epistemological foundation altogether, and to flirt with the coherence theory of truth. It is widely accepted that trying to make the connection between thought and experience through basic sentences depends on an untenable myth of the given.















































Still, in spite of these concerns, the problem, least of mention, is of defining knowledge in terms of true beliefs plus some favoured relations between the believer and the facts that began with Platos view in the Theaetetus, that knowledge is true belief, and some logos. Due of its nonsynthetic epistemology, the enterprising of studying the actual formation of knowledge by human beings, without aspiring to certify those processes as rational, or its proof against scepticism or even apt to yield the truth. Natural epistemology would therefore blend into the psychology of learning and the study of episodes in the history of science. The scope for external or philosophical reflection of the kind that might result in scepticism or its refutation is markedly diminished. Despite the fact that the terms of modernity are so distinguished as exponents of the approach include Aristotle, Hume, and J. S. Mills.

The task of the philosopher of a discipline would then be to reveal the correct method and to unmask counterfeits. Although this belief lay behind much positivist philosophy of science, few philosophers now subscribe to it. It places too well a confidence in the possibility of a purely previous first philosophy, or viewpoint beyond that of the work ones way of practitioners, from which their best efforts can be measured as good or bad. These standpoints now seem that too many philosophers to be fanciful, that the more modest of tasks that are actually adopted at various historical stages of investigation into different areas with the aim not so much of criticizing but more of systematization, in the presuppositions of a particular field at a particular tie. There is still a role for local methodological disputes within the community investigators of some phenomenon, with one approach charging that another is unsound or unscientific, but logic and philosophy will not, on the modern view, provide an independent arsenal of weapons for such battles, which indeed often come to seem more like political bids for ascendancy within a discipline.

This is an approach to the theory of knowledge that sees an important connection between the growth of knowledge and biological evolution. An evolutionary epistemologist claims that the development of human knowledge processed through some natural selection process, the best example of which is Darwins theory of biological natural selection. There is a widespread misconception that evolution proceeds according to some plan or direct, but it has neither, and the role of chance ensures that its future course will be unpredictable. Random variations in individual organisms create tiny differences in their Darwinian fitness. Some individuals have more offsprings than others, and the characteristics that increased their fitness thereby become more prevalent in future generations. Once upon a time, at least a mutation occurred in a human population in tropical Africa that changed the haemoglobin molecule in a way that provided resistance to malaria. This enormous advantage caused the new gene to spread, with the unfortunate consequence that sickle-cell anaemia came to exist.

Chance can influence the outcome at each stage: First, in the creation of genetic mutation, second, in wether the bearer lives long enough to show its effects, thirdly, in chance events that influence the individuals actual reproductive success, and fourth, in whether a gene even if favoured in one generation, is, happenstance, eliminated in the next, and finally in the many unpredictable environmental changes that will undoubtedly occur in the history of any group of organisms. As Harvard biologist Stephen Jay Gould has so vividly expressed that process over again, the outcome would surely be different. Not only might there not be humans, there might not even be anything like mammals.

We will often emphasis the elegance of traits shaped by natural selection, but the common idea that nature creates perfection needs to be analysed carefully. The extent to which evolution achieves perfection depends on exactly what you mean. If you mean Does natural selections always take the best path for the long-term welfare of a species? The answer is no. That would require adaption by group selection, and this is, unlikely. If you mean Does natural selection creates every adaption that would be valuable? The answer again, is no. For instance, some kinds of South American monkeys can grasp branches with their tails. The trick would surely also be useful to some African species, but, simply because of bad luck, none have it. Some combination of circumstances started some ancestral South American monkeys using their tails in ways that ultimately led to an ability to grab onto branches, while no such development took place in Africa. Mere usefulness of a trait does not necessitate a means in that what will understandably endure phylogenesis or evolution.

This is an approach to the theory of knowledge that sees an important connection between the growth of knowledge and biological evolution. An evolutionary epistemologist claims that the development of human knowledge proceeds through some natural selection process, the best example of which is Darwins theory of biological natural selection. The three major components of the model of natural selection are variation selection and retention. According to Darwins theory of natural selection, variations are not pre-designed to do certain functions. Rather, these variations that do useful functions are selected. While those that do not employ of some coordinates in that are regainfully purposed are also, not to any of a selection, as duly influenced of such a selection, that may have responsibilities for the visual aspects of a variational intentionally occurs. In the modern theory of evolution, genetic mutations provide the blind variations: Blind in the sense that variations are not influenced by the effects they would have-the likelihood of a mutation is not correlated with the benefits or liabilities that mutation would confer on the organism, the environment provides the filter of selection, and reproduction provides the retention. Fatnesses are achieved because those organisms with features that make them less adapted for survival do not survive in connection with other organisms in the environment that have features that are better adapted. Evolutionary epistemology applies this blind variation and selective retention model to the growth of scientific knowledge and to human thought processes overall.

The parallel between biological evolution and conceptual or epistemic evolution can be seen as either literal or analogical. The literal version of evolutionary epistemology deeds biological evolution as the main cause of the growth of knowledge. On this view, called the evolution of cognitive mechanic programs, by Bradie (1986) and the Darwinian approach to epistemology by Ruse (1986), that growth of knowledge occurs through blind variation and selective retention because biological natural selection itself is the cause of epistemic variation and selection. The most plausible version of the literal view does not hold that all human beliefs are innate but rather than the mental mechanisms that guide the acquisitions of non-innate beliefs are themselves innately and the result of biological natural selection. Ruse, (1986) demands of a version of literal evolutionary epistemology that he links to sociolology (Rescher, 1990).

On the analogical version of evolutionary epistemology, called the evolution of theorys program, by Bradie (1986). The Spenserians approach (after the nineteenth century philosopher Herbert Spencer) by Ruse (1986), the development of human knowledge is governed by a process analogous to biological natural selection, rather than by an instance of the mechanism itself. This version of evolutionary epistemology, introduced and elaborated by Donald Campbell (1974) as well as Karl Popper, sees the [partial] fit between theories and the world as explained by a mental process of trial and error known as epistemic natural selection.

Both versions of evolutionary epistemology are usually taken to be types of naturalized epistemology, because both take some empirical facts as a starting point for their epistemological project. The literal version of evolutionary epistemology begins by accepting evolutionary theory and a materialist approach to the mind and, from these, constructs an account of knowledge and its developments. In contrast, the metaphorical version does not require the truth of biological evolution: It simply draws on biological evolution as a source for the model of natural selection. For this version of evolutionary epistemology to be true, the model of natural selection need only apply to the growth of knowledge, not to the origin and development of species. Crudely put, evolutionary epistemology of the analogical sort could still be true even if Creationism is the correct theory of the origin of species.

Although they do not begin by assuming evolutionary theory, most analogical evolutionary epistemologists are naturalized epistemologists as well, their empirical assumptions, least of mention, implicitly come from psychology and cognitive science, not evolutionary theory. Sometimes, however, evolutionary epistemology is characterized in a seemingly non-naturalistic fashion. Campbell (1974) says that if one is expanding knowledge beyond what one knows, one has no choice but to explore without the benefit of wisdom, i.e., blindly. This, Campbell admits, makes evolutionary epistemology close to being a tautology (and so not naturalistic). Evolutionary epistemology does assert the analytic claim that when expanding ones knowledge beyond what one knows, one must precessed to something that is already known, but, more interestingly, it also makes the synthetic claim that when expanding ones knowledge beyond what one knows, one must proceed by blind variation and selective retention. This claim is synthetic because it can be empirically falsified. The central claim of evolutionary epistemology is synthetic, not analytic. If the central contradictory, which they are not. Campbell is right that evolutionary epistemology does have the analytic feature he mentions, but he is wrong to think that this is a distinguishing feature, since any plausible epistemology has the same analytic feature (Skagestad, 1978).

Two extraordinary issues lie to awaken the literature that involves questions about realism, i.e., What metaphysical commitment does an evolutionary epistemologist have to make? Progress, i.e., according to evolutionary epistemology, does knowledge develop toward a goal? With respect to realism, many evolutionary epistemologists endorse that is called hypothetical realism, a view that combines a version of epistemological scepticism and tentative acceptance of metaphysical realism. With respect to progress, the problem is that biological evolution is not goal-directed, but the growth of human knowledge seems to be. Campbell (1974) worries about the potential dis-analogy here but is willing to bite the stone of conscience and admit that epistemic evolution progress toward a goal (truth) while biologic evolution does not. Many another has argued that evolutionary epistemologists must give up the truth-topic sense of progress because a natural selection model is in essence, is non-teleological, as an alternative, following Kuhn (1970), and embraced in the accompaniment with evolutionary epistemology.

Among the most frequent and serious criticisms levelled against evolutionary epistemology is that the analogical version of the view is false because epistemic variation is not blind (Skagestad, 1978, 613-16, and Ruse, 1986, ch.2 (. Stein and Lipton (1990) have argued, however, that this objection fails because, while epistemic variation is not random, its constraints come from heuristics that, for the most part, are selective retention. Further, Stein and Lipton come to the conclusion that heuristics are analogous to biological pre-adaptions, evolutionary pre-biological pre-adaptions, evolutionary cursors, such as a half-wing, a precursor to a wing, which have some function other than the function of their descendable structures: The function of descendable structures, the function of their descendable character embodied to its structural foundations, is that of the guidelines of epistemic variation is, on this view, not the source of disanalogy, but the source of a more articulated account of the analogy.

Many evolutionary epistemologists try to combine the literal and the analogical versions (Bradie, 1986, and Stein and Lipton, 1990), saying that those beliefs and cognitive mechanisms, which are innate results from natural selection of the biological sort and those that are innate results from natural selection of the epistemic sort. This is reasonable as long as the two parts of this hybrid view are kept distinct. An analogical version of evolutionary epistemology with biological variation as its only source of blondeness would be a null theory: This would be the case if all our beliefs are innate or if our non-innate beliefs are not the result of blind variation. An appeal to the legitimate way to produce a hybrid version of evolutionary epistemology since doing so trivializes the theory. For similar reasons, such an appeal will not save an analogical version of evolutionary epistemology from arguments to the effect that epistemic variation is blind (Stein and Lipton, 1990).

Although it is a new approach to theory of knowledge, evolutionary epistemology has attracted much attention, primarily because it represents a serious attempt to flesh out a naturalized epistemology by drawing on several disciplines. In science is relevant to understanding the nature and development of knowledge, then evolutionary theory is among the disciplines worth a look. Insofar as evolutionary epistemology looks there, it is an interesting and potentially fruitful epistemological programme.

What makes a belief justified and what makes a true belief knowledge? Thinking that whether a belief deserves one of these appraisals is natural depends on what caused the depicted branch of knowledge to have the belief. In recent decades a number of epistemologists have pursued this plausible idea with a variety of specific proposals. Some causal theories of knowledge have it that a true belief that p is knowledge just in case it has the right causal connection to the fact that p. Such a criterion can be applied only to cases where the fact that p is a sort that can reach causal relations, as this seems to exclude mathematically and there necessary facts and perhaps any fact expressed by a universal generalization, and proponents of this sort of criterion have usually supposed that it is limited to perceptual representations where knowledge of particular facts about subjects environments.

For example, Armstrong (1973), predetermined that a position held by a belief in the form This perceived object is F is [non-inferential] knowledge if and only if the belief is a completely reliable sign that the perceived object is F, that is, the fact that the object is F contributed to causing the belief and its doing so depended on properties of the believer such that the laws of nature dictated that, for any subject P and perceived object y, if P has those properties and believed that y is F, then y is F. (Dretske (1981) offers a rather similar account, in terms of the beliefs being caused by a signal received by the perceiver that carries the information that the object is F).

Goldman (1986) has proposed an importantly different causal criterion, namely, that a true belief is knowledge if it is produced by a type of process that is globally and locally reliable. Causing true beliefs is sufficiently high is globally reliable if its propensity. Local reliability has to do with whether the process would have produced a similar but false belief in certain counterfactual situations alternative to the actual situation. This way of marking off true beliefs that are knowledge does not require the fact believed to be causally related to the belief, and so it could in principle apply to knowledge of any kind of truth.

Goldman requires the global reliability of the belief-producing process for the justification of a belief, he requires it also for knowledge because justification is required for knowledge. What he requires for knowledge, but does not require for justification is local reliability. His idea is that a justified true belief is knowledge if the type of process that produced it would not have produced it in any relevant counterfactual situation in which it is false. Its purported theory of relevant alternatives can be viewed as an attempt to provide a more satisfactory response to this tension in our thinking about knowledge. It attempts to characterize knowledge in a way that preserves both our belief that knowledge is an absolute concept and our belief that we have knowledge.

According to the theory, we need to qualify rather than deny the absolute character of knowledge. We should view knowledge as absolute, reactive to certain standards (Dretske, 1981 and Cohen, 1988). That is to say, in order to know a proposition, our evidence need not eliminate all the alternatives to that preposition, rather for us, that we can know our evidence eliminates al the relevant alternatives, where the set of relevant alternatives (a proper subset of the set of all alternatives) is determined by some standard. Moreover, according to the relevant alternatives view, and the standards determining that of the alternatives is raised by the sceptic are not relevant. If this is correct, then the fact that our evidence cannot eliminate the sceptics alternative does not lead to a sceptical result. For knowledge requires only the elimination of the relevant alternatives, so the relevant alternative view preserves in both strands in our thinking about knowledge. Knowledge is an absolute concept, but because the absoluteness is relative to a standard, we can know many things.

The interesting thesis that counts as a causal theory of justification (in the meaning of causal theory intended here) are that: A belief is justified in case it was produced by a type of process that is globally reliable, that is, its propensity to produce true beliefs-that can be defined (to a good approximation) As the proportion of the beliefs it produces (or would produce) that is true is sufficiently great.

This proposal will be adequately specified only when we are told (I) how much of the causal history of a belief counts as part of the process that produced it, (ii) which of the many types to which the process belongs is the type for purposes of assessing its reliability, and (iii) relative to why the world or worlds are the reliability of the process type to be assessed the actual world, the closet worlds containing the case being considered, or something else? Let us look at the answers suggested by Goldman, the leading proponent of a reliabilist account of justification.

(1) Goldman (1979, 1986) takes the relevant belief producing process to include only the proximate causes internal to the believer. So, for instance, when recently I believed that the telephone was ringing the process that produced the belief, for purposes of assessing reliability, includes just the causal chain of neural events from the stimulus in my ears inward ands other concurrent brain states on which the production of the belief depended: It does not include any events I the telephone, or the sound waves travelling between it and my ears, or any earlier decisions I made that were responsible for my being within hearing distance of the telephone at that time. It does seem intuitively plausible of a belief depends should be restricted to internal omnes proximate to the belief. Why? Goldman does not tell us. One answer that some philosophers might give is that it is because a beliefs being justified at a given time can depend only on facts directly accessible to the believers awareness at that time (for, if a believer ought to holds only beliefs that are justified, she can tell at any given time what beliefs would then be justified for her). However, this cannot be Goldmans answer because he wishes to include in the relevantly process neural events that are not directly accessible to consciousness.

(2) Once the reliabilist has told us how to delimit the process producing a belief, he needs to tell us which of the many types to which it belongs is the relevant type. Coincide, for example, the process that produces your current belief that you see a book before you. One very broad type to which that process belongs would be specified by coming to a belief as to something one perceives as a result of activation of the nerve endings in some of ones sense-organs. A constricted type, in which that unvarying processes belong would be specified by coming to a belief as to what one sees as a result of activation of the nerve endings in ones retinas. A still narrower type would be given by inserting in the last specification a description of a particular pattern of activation of the retinas particular cells. Which of these or other types to which the token process belongs is the relevant type for determining whether the type of process that produced your belief is reliable?

(3) Should the justification of a belief in a hypothetical, non-actual example turn on the reliability of the belief-producing process in the possible world of the example? That leads to the implausible result in that in a world run by a Cartesian demon-a powerful being who causes the other inhabitants of the world to have rich and coherent sets of perceptual and memory impressions that are all illusory the perceptual and memory beliefs of the other inhabitants are all unjustified, for they are produced by processes that are, in that world, quite unreliable. If we say instead that it is the reliability of the processes in the actual world that matters, we get the equally undesired result that if the actual world is a demon world then our perceptual and memory beliefs are all unjustified.

Goldmans solution (1986) is that the reliability of the process types is to be gauged by their performance in normal worlds, that is, worlds consistent with our general beliefs about the world . . . about the sorts of objects, events and changes that occur in it. This gives the intuitively right results for the problem cases just considered, but indicate by inference an implausible proportion of making compensations for alternative tending toward justification. If there are people whose general beliefs about the world are very different from mine, then there may, on this account, be beliefs that I can correctly regard as justified (ones produced by processes that are reliable in what I take to be a normal world) but that they can correctly regard as not justified.

However, these questions about the specifics are dealt with, and there are reasons for questioning the basic idea that the criterion for a beliefs being justified is its being produced by a reliable process. Thus and so, doubt about the sufficiency of the reliabilist criterion is prompted by a sort of example that Goldman himself uses for another purpose. Suppose that being in brain-state ‘B’ always causes one to believe that one is in brained-state ‘B’. Here the reliability of the belief-producing process is perfect, but we can readily imagine circumstances in which a person goes into grain-state ‘B’ and therefore has the belief in question, though this belief is by no means justified (Goldman, 1979). Doubt about the necessity of the condition arises from the possibility that one might know that one has strong justification for a certain belief and yet that knowledge is not what actually prompts one to believe. For example, I might be well aware that, having read the weather bureaus forecast that it will be much hotter tomorrow. I have ample reason to be confident that it will be hotter tomorrow, but I irrationally refuse to believe it until Wally tells me that he feels in his joints that it will be hotter tomorrow. Here what prompts me to believe dors not justify my belief, but my belief is nevertheless justified by my knowledge of the weather bureaus prediction and of its evidential force: I can advert to any disavowable inference that I ought not to be holding the belief. Indeed, given my justification and that there is nothing untoward about the weather bureaus prediction, my belief, if true, can be counted knowledge. This sorts of example raises doubt whether any causal conditions, are it a reliable process or something else, is necessary for either justification or knowledge.

Philosophers and scientists alike, have often held that the simplicity or parsimony of a theory is one reason, all else being equal, to view it as true. This goes beyond the unproblematic idea that simpler theories are easier to work with and gave greater aesthetic appeal.

One theory is more parsimonious than another when it postulates fewer entities, processes, changes or explanatory principles: The simplicity of a theory depends on essentially the same consecrations, though parsimony and simplicity obviously become the same. Demanding clarification of what makes one theory simpler or more parsimonious is plausible than another before the justification of these methodological maxims can be addressed.

If we set this description problem to one side, the major normative problem is as follows: What reason is there to think that simplicity is a sign of truth? Why should we accept a simpler theory instead of its more complex rivals? Newton and Leibniz thought that the answer was to be found in a substantive fact about nature. In Principia, Newton laid down as his first Rule of Reasoning in Philosophy that nature does nothing in vain . . . for Nature is pleased with simplicity and affects not the pomp of superfluous causes. Leibniz hypothesized that the actual world obeys simple laws because Gods taste for simplicity influenced his decision about which world to actualize.

The tragedy of the Western mind, described by Koyré, is a direct consequence of the stark Cartesian division between mind and world. We discovered the certain principles of physical reality, said Descartes, not by the prejudices of the senses, but by the light of reason, and which thus possess so great evidence that we cannot doubt of their truth. Since the real, or that which actually exists external to ourselves, was in his view only that which could be represented in the quantitative terms of mathematics, Descartes conclude that all quantitative aspects of reality could be traced to the deceitfulness of the senses.

The most fundamental aspect of the Western intellectual tradition is the assumption that there is a fundamental division between the material and the immaterial world or between the realm of matter and the realm of pure mind or spirit. The metaphysical frame-work based on this assumption is known as ontological dualism. As the word dual implies, the framework is predicated on an ontology, or a conception of the nature of God or Being, that assumes reality has two distinct and separable dimensions. The concept of Being as continuous, immutable, and having a prior or separate existence from the world of change dates from the ancient Greek philosopher Parmenides. The same qualities were associated with the God of the Judeo-Christian tradition, and they were considerably amplified by the role played in theology by Platonic and Neoplatonic philosophy.

Nicolas Copernicus, Galileo, Johannes Kepler, and Isaac Newton were all inheritors of a cultural tradition in which ontological dualism was a primary article of faith. Hence the idealization of the mathematical ideal as a source of communion with God, which dates from Pythagoras, provided a metaphysical foundation for the emerging natural sciences. This explains why, the creators of classical physics believed that doing physics was a form of communion with the geometrical and mathematical forms resident in the perfect mind of God. This view would survive in a modified form in what is now known as Einsteinian epistemology and accounts in no small part for the reluctance of many physicists to accept the epistemology associated with the Copenhagen Interpretation.

At the beginning of the nineteenth century, Pierre-Simon LaPlace, along with a number of other French mathematicians, advanced the view that the science of mechanics constituted a complete view of nature. Since this science, by observing its epistemology, had revealed itself to be the fundamental science, the hypothesis of God was, they concluded, entirely unnecessary.

LaPlace is recognized for eliminating not only the theological component of classical physics but the entire metaphysical component as well. The epistemology of science requires, he said, that we proceed by inductive generalizations from observed facts to hypotheses that are tested by observed conformity of the phenomena. What was unique about LaPlaces view of hypotheses was his insistence that we cannot attribute reality to them. Although concepts like force, mass, motion, cause, and laws are obviously present in classical physics, they exist in LaPlaces view only as quantities. Physics is concerned, he argued, with quantities that we associate as a matter of convenience with concepts, and the truths about nature are only the quantities.

As this view of hypotheses and the truths of nature as quantities was extended in the nineteenth century to a mathematical description of phenomena like heat, light, electricity, and magnetism. LaPlaces assumptions about the actual character of scientific truths seemed correct. This progress suggested that if we could remove all thoughts about the nature of or the source of phenomena, the pursuit of strictly quantitative concepts would bring us to a complete description of all aspects of physical reality. Subsequently, figures like Comte, Kirchhoff, Hertz, and Poincaré developed a program for the study of nature hat was quite different from that of the original creators of classical physics.

The seventeenth-century view of physics as a philosophy of nature or as natural philosophy was displaced by the view of physics as an autonomous science that was the science of nature. This view, which was premised on the doctrine of positivism, promised to subsume all of nature with a mathematical analysis of entities in motion and claimed that the true understanding of nature was revealed only in the mathematical description. Since the doctrine of positivism assumes that the knowledge we call physics resides only in the mathematical formalism of physical theory, it disallows the prospect that the vision of physical reality revealed in physical theory can have any other meaning. In the history of science, the irony is that positivism, which was intended to banish metaphysical concerns from the domain of science, served to perpetuate a seventeenth-century metaphysical assumption about the relationship between physical reality and physical theory.

Epistemology since Hume and Kant has drawn back from this theological underpinning. Indeed, the very idea that nature is simple (or uniform) has come in for a critique. The view has taken hold that a preference for simple and parsimonious hypotheses is purely methodological: It is constitutive of the attitude we call scientific and makes no substantive assumption about the way the world is.

A variety of otherwise diverse twentieth-century philosophers of science have attempted, in different ways, to flesh out this position. Two examples must suffice here: Hesse (1969) as, for summaries of other proposals. Popper (1959) holds that scientists should prefer highly falsifiable (improbable) theories: He tries to show that simpler theories are more falsifiable, also Quine (1966), in contrast, sees a virtue in theories that are highly probable, he argues for a general connection between simplicity and high probability.

Both these proposals are global. They attempt to explain why simplicity should be part of the scientific method in a way that spans all scientific subject matters. No assumption about the details of any particular scientific problem serves as a premiss in Poppers or Quines arguments.

Newton and Leibniz thought that the justification of parsimony and simplicity flows from the hand of God: Popper and Quine try to justify these methodologically median of importance is without assuming anything substantive about the way the world is. In spite of these differences in approach, they have something in common. They assume that all users of parsimony and simplicity in the separate sciences can be encompassed in a single justifying argument. That recent developments in confirmation theory suggest that this assumption should be scrutinized. Good (1983) and Rosenkrantz (1977) has emphasized the role of auxiliary assumptions in mediating the connection between hypotheses and observations. Whether a hypothesis is well supported by some observations, or whether one hypothesis is better supported than another by those observations, crucially depends on empirical background assumptions about the inference problem here. The same view applies to the idea of prior probability (or, prior plausibility). In of a single hypo-physical science if chosen as an alternative to another even though they are equally supported by current observations, this must be due to an empirical background assumption.

Principles of parsimony and simplicity mediate the epistemic connection between hypotheses and observations. Perhaps these principles are able to do this because they are surrogates for an empirical background theory. It is not that there is one background theory presupposed by every appeal to parsimony; This has the quantifier order backwards. Rather, the suggestion is that each parsimony argument is justified only to each degree that it reflects an empirical background theory about the subjective matter. On this theory is brought out into the open, but the principle of parsimony is entirely dispensable (Sober, 1988).

This local approach to the principles of parsimony and simplicity resurrects the idea that they make sense only if the world is one way rather than another. It rejects the idea that these maxims are purely methodological. How defensible this point of view is, will depend on detailed case studies of scientific hypothesis evaluation and on further developments in the theory of scientific inference.

It is usually not found of one and the same that, an inference is a (perhaps very complex) act of thought by virtue of which act (1) I pass from a set of one or more propositions or statements to a proposition or statement and (2) it appears that the latter are true if the former is or are. This psychological characterization has occurred over a wider summation of literature under more lesser than inessential variations. Desiring a better characterization of inference is natural. Yet attempts to do so by constructing a fuller psychological explanation fail to comprehend the grounds on which inference will be objectively valid-A point elaborately made by Gottlob Frége. Attempts to understand the nature of inference through the device of the representation of inference by formal-logical calculations or derivations better (1) leave us puzzled about the relation of formal-logical derivations to the informal inferences they are supposedly to represent or reconstruct, and (2) leaves us worried about the sense of such formal derivations. Are these derivations inference? Are not informal inferences needed in order to apply the rules governing the constructions of formal derivations (inferring that this operation is an application of that formal rule)? These are concerns cultivated by, for example, Wittgenstein.

Coming up with an adequate characterization of inference-and even working out what would count as a very adequate characterization here is demandingly by no means nearly some resolved philosophical problem.

The rule of inference, as for raised by Lewis Carroll, the Zeno-like problem of how a proof ever gets started. Suppose I have as premises (I) p and (ii) p ÿ q. Can I infer q? Only, it seems, if I am sure of (iii) (p & p ÿq) ÿ q. Can I then infer q? Only, it seems, if I am sure that (iv) (p & p ÿ q & (p & p ÿ q) ÿ q) ÿ q. For each new axiom (N) I need a further axiom (N + 1) telling me that the set so far implies q, and the regress never stops. The usual solution is to treat a system as containing not only axioms, but also rules of inference, allowing movement from the axioms. The rule modus ponens allow us to pass from the first premise to q. Carrolls puzzle shows that distinguishing two theoretical categories is essential, although there may be choice about which theses to put in which category.

Traditionally, a proposition that is not a conditional, as with the affirmative and negative, modern opinion is wary of the distinction, since what appears categorical may vary with the choice of a primitive vocabulary and notation. Apparently categorical propositions may also turn out to be disguised conditionals: ‘X’ is intelligent (categorical?) Equivalent, if ‘X’ is given a range of tasks, she does them better than many people (conditional?). The problem is not merely one of classification, since deep metaphysical questions arise when facts that seem to be categorical and therefore solid, come to seem by contrast conditional, or purely hypothetical or potential.

Its condition of some classified necessity is so proven sufficient that if ‘p’ is a necessary condition of ‘q’, then ‘q’ cannot be true unless ‘p’; is true? If p is a sufficient condition, thus steering well is a necessary condition of driving in a satisfactory manner, but it is not sufficient, for one can steer well but drive badly for other reasons. Confusion may result if the distinction is not heeded. For example, the statement that ‘A’ causes ‘B’ may be interpreted to mean that ‘A’ is itself a sufficient condition for ‘B’, or that it is only a necessary condition fort ‘B’, or perhaps a necessary parts of a total sufficient condition. Lists of conditions to be met for satisfying some administrative or legal requirement frequently attempt to give individually necessary and jointly sufficient sets of conditions.

What is more, that if any proposition of the form if ‘p’ then ‘q’. The condition hypothesized, ‘p’. Is called the antecedent of the conditionals, and ‘q’, the consequent? Various kinds of conditional have been distinguished. Its weakest is that of material implication, merely telling that either ‘not-p’, or ‘q’. Stronger conditionals include elements of modality, corresponding to the thought that if ‘p’ is truer then ‘q’ must be true. Ordinary language is very flexible in its use of the conditional form, and there is controversy whether conditionals are better treated semantically, yielding differently finds of conditionals with different meanings, or pragmatically, in which case there should be one basic meaning with surface differences arising from other implicatures.

It follows from the definition of strict implication that a necessary proposition is strictly implied by any proposition, and that an impossible proposition strictly implies any proposition. If strict implication corresponds to ‘q’ follows from ‘p’, then this means that a necessary proposition follows from anything at all, and anything at all follows from an impossible proposition. This is a problem if we wish to distinguish between valid and invalid arguments with necessary conclusions or impossible premises.

The Humean problem of induction is that if we would suppose that there is some property A concerning and observational or an experimental situation, and that out of a large number of observed instances of ‘A’, some fraction m/n (possibly equal to 1) has also been instances of some logically independent property ‘B’. Suppose further that the background proportionate circumstances not specified in these descriptions have been varied to a substantial degree and that there is no collateral information available concerning the frequency of Bs among As or concerning causal or nomologically connections between instances of ‘A’ and instances of ‘B’.

In this situation, an enumerative or instantial induction inference would move rights from the premise, that m/n of observed ‘A’s’ are ‘B’s’ to the conclusion that approximately m/n of all ‘A’s’ are ‘B’s’. (The usual probability qualification will be assumed to apply to the inference, rather than being part of the conclusion.) Here the class of As should be taken to include not only unobserved ‘A’s’ and future ‘A’s’, but also possible or hypothetical As (an alternative conclusion would concern the probability or likelihood of the adjacently observed ‘A’ being a ‘B’).

The traditional or Humean problem of induction, often referred to simply as the problem of induction, is the problem of whether and why inferences that fit this schema should be considered rationally acceptable or justified from an epistemic or cognitive standpoint, i.e., whether and why reasoning in this way is likely to lead to true claims about the world. Is there any sort of argument or rationale that can be offered for thinking that conclusions reached in this way are likely to be true in the corresponding premisses is true Sor even that their chances of truth are significantly enhanced?

Humes discussion of this issue deals explicitly only with cases where all observed ‘A’s’ are ‘B’s’ and his argument applies just as well to the more general case. His conclusion is entirely negative and sceptical: Inductive inferences are not rationally justified, but are instead the result of an essentially a-rational process, custom or habit. Hume (1711-76) challenges the proponent of induction to supply a cogent line of reasoning that leads from an inductive premise to the corresponding conclusion and offers an extremely influential argument in the form of a dilemma (a few times referred to as Humes fork), that either our actions are determined, in which case we are not responsible for them, or they are the result of random events, under which case we are also not responsible for them.

Such reasoning would, he argues, have to be either deductively demonstrative reasoning in the concerning relations of ideas or experimental, i.e., empirical, that reasoning concerning matters of fact or existence. It cannot be the former, because all demonstrative reasoning relies on the avoidance of contradiction, and it is not a contradiction to suppose that the course of nature may change, that an order that was observed in the past and not of its continuing against the future: But it cannot be, as the latter, since any empirical argument would appeal to the success of such reasoning about an experience, and the justifiability of generalizing from experience are precisely what is at issue-so that any such appeal would be question-begging. Hence, Hume concludes that there can be no such reasoning (1748).

An alternative version of the problem may be obtained by formulating it with reference to the so-called Principle of Induction, which says roughly that the future will resemble the past or, somewhat better, that unobserved cases will resemble observed cases. An inductive argument may be viewed as enthymematic, with this principle serving as a supposed premiss, in which case the issue is obviously how such a premiss can be justified. Humes argument is then that no such justification is possible: The principle cannot be justified a prior because having possession of been true in experiences without obviously begging the question is not contradictory to have possession of been true in experiences without obviously begging the question.

The predominant recent responses to the problem of induction, at least in the analytic tradition, in effect accept the main conclusion of Humes argument, namely, that inductive inferences cannot be justified in the sense of showing that the conclusion of such an inference is likely to be true if the premise is true, and thus attempt to find another sort of justification for induction. Such responses fall into two main categories: (i) Pragmatic justifications or vindications of induction, mainly developed by Hans Reichenbach (1891-1953), and (ii) ordinary language justifications of induction, whose most important proponent is Frederick, Peter Strawson (1919-). In contrast, some philosophers still attempt to reject Humes dilemma by arguing either (iii) That, contrary to appearances, induction can be inductively justified without vicious circularity, or (iv) that an anticipatory justification of induction is possible after all. In that:

(1) Reichenbachs view is that induction is best regarded, not as a form of inference, but rather as a method for arriving at posits regarding, i.e., the proportion of As remain additionally of Bs. Such a posit is not a claim asserted to be true, but is instead an intellectual wager analogous to a bet made by a gambler. Understood in this way, the inductive method says that one should posit that the observed proportion is, within some measure of an approximation, the true proportion and then continually correct that initial posit as new information comes in.

The gamblers bet is normally an appraised posit, i.e., he knows the chances or odds that the outcome on which he bets will actually occur. In contrast, the inductive bet is a blind posit: We do not know the chances that it will succeed or even that success is that it will succeed or even that success is possible. What we are gambling on when we make such a bet is the value of a certain proportion in the independent world, which Reichenbach construes as the limit of the observed proportion as the number of cases increases to infinity. Nevertheless, we have no way of knowing that there are even such a limit, and no way of knowing that the proportion of As are in addition of Bs converges in the end on some stable value than varying at random. If we cannot know that this limit exists, then we obviously cannot know that we have any definite chance of finding it.

What we can know, according to Reichenbach, is that if there is a truth of this sort to be found, the inductive method will eventually find it. That this is so is an analytic consequence of Reichenbachs account of what it is for such a limit to exist. The only way that the inductive method of making an initial posit and then refining it in light of new observations can fail eventually to arrive at the true proportion is if the series of observed proportions never converges on any stable value, which means that there is no truth to be found pertaining the proportion of ‘A’s’ additionally constitute ‘B’s’. Thus, induction is justified, not by showing that it will succeed or indeed, that it has any definite likelihood of success, but only by showing that it will succeed if success is possible. Reichenbachs claim is that no more than this can be established for any method, and hence that induction gives us our best chance for success, our best gamble in a situation where there is no alternative to gambling.

This pragmatic response to the problem of induction faces several serious problems. First, there are indefinitely many other methods for arriving at posits for which the same sort of defence can be given-methods that yield the same result as the inductive method over time but differ arbitrarily before long. Despite the efforts of others, it is unclear that there is any satisfactory way to exclude such alternatives, in order to avoid the result that any arbitrarily chosen short-term posit is just as reasonable as the inductive posit. Second, even if there is a truth of the requisite sort to be found, the inductive method is only guaranteed to find it or even to come within any specifiable distance of it in the indefinite long run. All the same, any actual application of inductive results always takes place in the presence to the future eventful states in making the relevance of the pragmatic justification to actual practice uncertainly. Third, and most important, it needs to be emphasized that Reichenbachs response to the problem simply accepts the claim of the Humean sceptic that an inductive premise never provides the slightest reason for thinking that the corresponding inductive conclusion is true. Reichenbach himself is quite candid on this point, but this does not alleviate the intuitive implausibility of saying that we have no more reason for thinking that our scientific and commonsense conclusions that result in the induction of it . . . is true than, to use Reichenbachs own analogy (1949), a blind man wandering in the mountains who feels an apparent trail with his stick has for thinking that following it will lead him to safety.

An approach to induction resembling Reichenbachs claiming in that those particular inductive conclusions are posits or conjectures, than the conclusions of cogent inferences, is offered by Popper. However, Poppers view is even more overtly sceptical: It amounts to saying that all that can ever be said in favour of the truth of an inductive claim is that the claim has been tested and not yet been shown to be false.

(2) The ordinary language response to the problem of induction has been advocated by many philosophers, none the less, Strawson claims that the question whether induction is justified or reasonable makes sense only if it tacitly involves the demand that inductive reasoning meet the standards appropriate to deductive reasoning, i.e., that the inductive conclusions are shown to follow deductively from the inductive assumption. Such a demand cannot, of course, be met, but only because it is illegitimate: Inductive and deductive reasons are simply fundamentally different kinds of reasoning, each possessing its own autonomous standards, and there is no reason to demand or expect that one of these kinds meet the standards of the other. Whereas, if induction is assessed by inductive standards, the only ones that are appropriate, then it is obviously justified.

The problem here is to understand to what this allegedly obvious justification of an induction amount. In his main discussion of the point (1952), Strawson claims that it is an analytic true statement that believing it a conclusion for which there is strong evidence is reasonable and an analytic truth that inductive evidence of the sort captured by the schema presented earlier constitutes strong evidence for the corresponding inductive conclusion, thus, apparently yielding the analytic conclusion that believing it a conclusion for which there is inductive evidence is reasonable. Nevertheless, he also admits, indeed insists, that the claim that inductive conclusions will be true in the future is contingent, empirical, and may turn out to be false (1952). Thus, the notion of reasonable belief and the correlative notion of strong evidence must apparently be understood in ways that have nothing to do with likelihood of truth, presumably by appeal to the standard of reasonableness and strength of evidence that are accepted by the community and are embodied in ordinary usage.

Understood in this way, Strawsons response to the problem of inductive reasoning does not speak to the central issue raised by Humean scepticism: The issue of whether the conclusions of inductive arguments are likely to be true. It amounts to saying merely that if we reason in this way, we can correctly call ourselves reasonable and our evidence strong, according to our accepted community standards. Nevertheless, to the undersealing of issue of wether following these standards is a good way to find the truth, the ordinary language response appears to have nothing to say.

(3) The main attempts to show that induction can be justified inductively have concentrated on showing that such as a defence can avoid circularity. Skyrms (1975) formulate, perhaps the clearest version of this general strategy. The basic idea is to distinguish different levels of inductive argument: A first level in which induction is applied to things other than arguments: A second level in which it is applied to arguments at the first level, arguing that they have been observed to succeed so far and hence are likely to succeed in general: A third level in which it is applied in the same way to arguments at the second level, and so on. Circularity is allegedly avoided by treating each of these levels as autonomous and justifying the argument at each level by appeal to an argument at the next level.

One problem with this sort of move is that even if circularity is avoided, the movement to higher and higher levels will clearly eventually fail simply for lack of evidence: A level will reach at which there have been enough successful inductive arguments to provide a basis for inductive justification at the next higher level, and if this is so, then the whole series of justifications collapses. A more fundamental difficulty is that the epistemological significance of the distinction between levels is obscure. If the issue is whether reasoning in accord with the original schema offered above ever provides a good reason for thinking that the conclusion is likely to be true, then it still seems question-begging, even if not flatly circular, to answer this question by appeal to anther argument of the same form.

(4) The idea that induction can be justified on a pure priori basis is in one way the most natural response of all: It alone treats an inductive argument as an independently cogent piece of reasoning whose conclusion can be seen rationally to follow, although perhaps only with probability from its premise. Such an approach has, however, only rarely been advocated (Russell, 19132 and BonJour, 1986), and is widely thought to be clearly and demonstrably hopeless.

Many on the reasons for this pessimistic view depend on general epistemological theses about the possible or nature of anticipatory cognition. Thus if, as Quine alleges, there is no a prior justification of any kind, then obviously a prior justification for induction is ruled out. Or if, as more moderate empiricists have in claiming some preexistent knowledge should be analytic, then again a prevenient justification for induction seems to be precluded, since the claim that if an inductive premise ids truer, then the conclusion is likely to be true does not fit the standard conceptions of analyticity. A consideration of these matters is beyond the scope of the present spoken exchange.

There are, however, two more specific and quite influential reasons for thinking that an early approach is impossible that can be briefly considered, first, there is the assumption, originating in Hume, but since adopted by very many of others, that a move forward in the defence of induction would have to involve turning induction into deduction, i.e., showing, per impossible, that the inductive conclusion follows deductively from the premise, so that it is a formal contradiction to accept the latter and deny the former. However, it is unclear why a prior approach need be committed to anything this strong. It would be enough if it could be argued that it is deductively unlikely that such a premise is true and corresponding conclusion false.

Reichenbach defends his view that pragmatic justification is the best that is possible by pointing out that a completely chaotic world in which there is simply not true conclusion to be found as to the proportion of As in addition that occur of, but Bs is neither impossible nor unlikely from a purely a prior standpoint, the suggestion being that therefore there can be no a prior reason for thinking that such a conclusion is true. Nevertheless, there is still a substring wayin laying that a chaotic world is a prior neither impossible nor unlikely without any further evidence does not show that such a world os not a prior unlikely and a world containing such-and-such regularity might anticipatorially be somewhat likely in relation to an occurrence of a long-run patten of evidence in which a certain stable proportion of observed As are Bs ~. An occurrence, it might be claimed, that would be highly unlikely in a chaotic world (BonJour, 1986).

So, to a better understanding of induction we should then term is most widely used for any process of reasoning that takes us from empirical premises to empirical conclusions supported by the premises, but not deductively entailed by them. Inductive arguments are therefore kinds of applicative arguments, in which something beyond the content of the premise is inferred as probable or supported by them. Induction is, however, commonly distinguished from arguments to theoretical explanations, which share this applicative character, by being confined to inferences in which he conclusion involves the same properties or relations as the premises. The central example is induction by simple enumeration, where from premises telling that Fa, Fb, Fc . . . where a, b, cs, are all of some kind G, it is inferred that Gs from outside the sample, such as future Gs, will be F, or perhaps that all Gs are F. In this, which and the other persons deceive them, children may infer that everyone is a deceiver: Different, but similar inferences of a property by some object to the same objects future possession of the same property, or from the constancy of some law-like pattern in events and states of affairs ti its future constancy. All objects we know of attract each other with a force inversely proportional to the square of the distance between them, so perhaps they all do so, and will always do so.

The rational basis of any inference was challenged by Hume, who believed that induction presupposed belie in the uniformity of nature, but that this belief has no defence in reason, and merely reflected a habit or custom of the mind. Hume was not therefore sceptical about the role of reason in either explaining it or justifying it. Trying to answer Hume and to show that there is something rationally compelling about the inference referred to as the problem of induction. It is widely recognized that any rational defence of induction will have to partition well-behaved properties for which the inference is plausible (often called projectable properties) from badly behaved ones, for which it is not. It is also recognized that actual inductive habits are more complex than those of similar enumeration, and that both common sense and science pay attention to such giving factors as variations within the sample giving us the evidence, the application of ancillary beliefs about the order of nature, and so on.

Nevertheless, the fundamental problem remains that ant experience condition by application show us only events occurring within a very restricted part of a vast spatial and temporal order about which we then come to believe things.

Uncompounded by its belonging of a confirmation theory finding of the measure to which evidence supports a theory fully formalized confirmation theory would dictate the degree of confidence that a rational investigator might have in a theory, given some-body of evidence. The grandfather of confirmation theory is Gottfried Leibniz (1646-1718), who believed that a logically transparent language of science would be able to resolve all disputes. In the 20th century a fully formal confirmation theory was a main goal of the logical positivist, since without it the central concept of verification by empirical evidence itself remains distressingly unscientific. The principal developments were due to Rudolf Carnap (1891-1970), culminating in his Logical Foundations of Probability (1950). Carnaps idea was that the measure necessitated would be the proportion of logically possible states of affairs in which the theory and the evidence both hold, compared ti the number in which the evidence itself holds that the probability of a preposition, relative to some evidence, is a proportion of the range of possibilities under which the proposition is true, compared to the total range of possibilities left by the evidence. The difficulty with the theory lies in identifying sets of possibilities so that they admit of measurement. It therefore demands that we can put a measure on the range of possibilities consistent with theory and evidence, compared with the range consistent with the evidence alone.

Among the obstacles the enterprise meets, is the fact that while evidence covers only a finite range of data, the hypotheses of science may cover an infinite range. In addition, confirmation proves to vary with the language in which the science is couched, and the Carnapian programme has difficulty in separating genuinely confirming variety of evidence from less compelling repetition of the same experiment. Confirmation also proved to be susceptible to acute paradoxes. Finally, scientific judgement seems to depend on such intangible factors as the problems facing rival theories, and most workers have come to stress instead the historically situated scene of what would appear as a plausible distinction of a scientific knowledge at a given time.

Arose to the paradox of which when a set of apparent incontrovertible premises is given to unacceptable or contradictory conclusions. To solve a paradox will involve showing either that there is a hidden flaw in the premises, or that the reasoning is erroneous, or that the apparently unacceptable conclusion can, in fact, be tolerated. Paradoxes are therefore important in philosophy, for until one is solved it shows that there is something about our reasoning and our concepts that we do not understand. What is more, and somewhat loosely, a paradox is a compelling argument from unacceptable premises to an unacceptable conclusion: More strictly speaking, a paradox is specified to be a sentence that is true if and only if it is false. A characterized objection lesson of it would be: The displayed sentence is false.

Seeing that this sentence is false if true is easy, and true if false, a paradox, in either of the senses distinguished, presents an important philosophical challenger. Epistemologists are especially concerned with various paradoxes having to do with knowledge and belief. In other words, for example, the Knower paradox is an argument that begins with apparently impeccable premisses about the concepts of knowledge and inference and derives an explicit contradiction. The origin of the reasoning is the surprise examination paradox: A teacher announces that there will be a surprise examination next week. A clever student argues that this is impossible. The test cannot be on Friday, the last day of the week, because it would not be a surprise. We would know the day of the test on Thursday evening. This means we can also rule out Thursday. For after we learn that no test has been given by Wednesday, we would know the test is on Thursday or Friday, and would already know that it s not on Friday and would already know that it is not on Friday by the previous reasoning. The remaining days can be eliminated in the same manner.

This puzzle has over a dozen variants. The first was probably invented by the Swedish mathematician Lennard Ekbon in 1943. Although the first few commentators regarded the reverse elimination argument as cogent, every writer on the subject since 1950 agrees that the argument is unsound. The controversy has been over the proper diagnosis of the flaw.

Initial analyses of the subjects argument tried to lay the blame on a simple equivocation. Their failure led to more sophisticated diagnoses. The general format has been an assimilation to better-known paradoxes. One tradition casts the surprise examination paradox as a self-referential problem, as fundamentally akin to the Liar, the paradox of the Knower, or Gödels incompleteness theorem. That in of itself, says enough that Kaplan and Montague (1960) distilled the following self-referential paradox, the Knower. Consider the sentence: (S) the negation of this sentence is known (to be true). Suppose that (S) is true. Then its negation is known and hence true. However, if its negation is true, then (S) must be false. Therefore (s) is false, or what is the name, the negation of (S) is true.

Nevertheless, foundationalisms also differ as to what further constraints, if any, are put on foundations. Historically, it has been common to require of the foundations of knowledge that they exhibit certain epistemic immunities, as we might put it, immunity from error, refutation or doubt. Thus Descartes, along with many other seventeenth and eighteenth-century philosophers, took it that any knowledge worthy of the name would be based on cognations the truth of which is guaranteed (infallible), that were maximally stable, immune from ever being shown to be mistaken, as incorrigible, and concerning which no reasonable doubt could be raised (indubitable). Hence the search in the Meditations for a divine guarantee of our faculty of rational intuition. Criticisms of Foundationalism have often been directed at these constraints: Lehrer, 1974, Will, 1974? Both responded to in Alston, 1989. It is important to realize that a position that is Foundationalist in a distinctive sense can be formulated without imposing any such requirements on foundations.

There are various ways of distinguishing types of Foundationalist epistemology by the use of the variations we have been enumerating. Plantinga (1983), has put forwards an influential innovation of criterial Foundationalism, specified in terms of limitations on the foundations. He construes this as a disjunction of ancient and medieval Foundationalism, which takes foundations to comprise what is self-evidently and evident to he senses, and modern Foundationalism that replaces evidently to the senses with incorrigible, which in practice was taken to apply only to beliefs about ones present states of consciousness. Plantinga himself developed this notion in the context of arguing those items outside this territory, in particular certain beliefs about God, could also be immediately justified. A popular recent distinction is between what is variously called strong or extreme Foundationalism and moderate, modest or minimal Foundationalism, with the distinction depending on whether various epistemic immunities are required of foundations. Finally, its distinction is simple and iterative Foundationalism (Alston, 1989), depending on whether it is required of a foundation only that it is immediately justified, or whether it is also required that the higher level belief that the firmer belief is immediately justified is itself immediately justified. Suggesting only that the plausibility of the stronger requirement stems from a level confusion between beliefs on different levels.

The classic opposition is between Foundationalism and Coherentism. Coherentism denies any immediate justification. It deals with the regress argument by rejecting linear chains of justification and, in effect, taking the total system of belief to be epistemically primary. A particular belief is justified yo the extent that it is integrated into a coherent system of belief. More recently into a pragmatist like John Dewey has developed a position known as contextualism, which avoids ascribing any overall structure to knowledge. Questions concerning justification can only arise in particular context, defined in terms of assumptions that are simply taken for granted, though they can be questioned in other contexts, where other assumptions will be privileged.

Foundationalism can be attacked both in its commitment to immediate justification and in its claim that all mediately justified beliefs ultimately depend on the former. Though, it is the latter that is the positions weakest point, most of the critical fire has been detected to the former. As pointed out about much of this criticism has been directly against some particular form of immediate justification, ignoring the possibility of other forms. Thus, much anti-Foundationalist artillery has been directed at the myth of the given. The idea that facts or things are given to consciousness in a pre-conceptual, pre-judgmental mode, and that beliefs can be justified on that basis (Sellars, 1963). The most prominent general argument against immediate justification is a level ascent argument, according to which whatever is taken ti immediately justified a belief that the putative justifier has in supposing to do so. Hence, since the justification of the higher level belief after all (BonJour, 1985). We lack adequate support for any such higher level requirements for justification, and if it were imposed we would be launched on an infinite undergo regress, for a similar requirement would hold equally for the higher level belief that the original justifier was efficacious.

Coherence is a major player in the theatre of knowledge. There are coherence theories of belief, truth, and justification. These combine in various ways to yield theories of knowledge. We will proceed from belief through justification to truth. Coherence theories of belief are concerned with the content of beliefs. Consider a belief you now have, the beliefs that you are reading a page in a book, so what makes that belief the belief that it is? What makes it the belief that you are reading a page in a book than the belief hat you have a monster in the garden?

One answer is that the belief has a coherent place or role in a system of beliefs. Perception has an influence on belief. You respond to sensory stimuli by believing that you are reading a page in a book rather than believing that you have a centaur in the garden. Belief has an influence on action. You will act differently if you believe that you are reading a page than if you believe something about a centaur. Perspicacity and action undermine the content of belief, however, the same stimuli may produce various beliefs and various beliefs may produce the same action. The role that gives the belief the content it has in the role it plays in a network of relations to the beliefs, the role in inference and implications, for example, I refer different things from believing that I am inferring different things from believing that I am reading a page in a book than from any other beliefs, just as I infer that belief from any other belief, just as I infer that belief from different things than I infer other beliefs from.

The input of perception and the output of an action supplement the centre role of the systematic relations the belief has to other beliefs, but it is the systematic relations that give the belief the specific content it has. They are the fundamental source of the content of beliefs. That is how coherence comes in. A belief has the content that it does because of the way in which it coheres within a system of beliefs (Rosenberg, 1988). We might distinguish weak coherence theories of the content of beliefs from strong coherence theories. Weak coherence theories affirm that coherences are one-determinant of the content of belief. Strong coherence theories of the contents of belief affirm that coherence is the sole determinant of the content of belief.

When we turn from belief to justification, we are in confronting a corresponding group of similarities fashioned by their coherences motifs. What makes one belief justified and another not? The answer is the way it coheres with the background system of beliefs. Again, there is a distinction between weak and strong theories of coherence. Weak theories tell us that the way in which a belief coheres with a background system of beliefs is one determinant of justification, other typical determinants being perception, memory and intuition. Strong theories, by contrast, tell us that justification is solely a matter of how a belief coheres with a system of beliefs. There is, however, another distinction that cuts across the distinction between weak and strong coherence theories of justification. It is the distinction between positive and negative coherence theories (Pollock, 1986). A positive coherence theory tells us that if a belief coheres with a background system of belief, then the belief is justified. A negative coherence theory tells us that if a belief fails to cohere with a background system of beliefs, then the belief is not justified. We might put this by saying that, according to a positive coherence theory, coherence has the power to produce justification, while according to a negative coherence theory, coherence has only the power to nullify justification.

A strong coherence theory of justification is a combination of a positive and a negative theory that tells us that a belief is justified if and only if it coheres with a background system of beliefs.

Traditionally, belief has been of epistemological interest in its propositional guise: S believes that p, where p is a proposition toward which an agent, S, exhibits an attitude of acceptance. Not all belief is of this sort. If I trust what you say, I believe you. And someone may believe in Mrs. Thatcher, or in a free-market economy, or in God. It is sometimes supposed that all belief is reducible to propositional belief, belief-that. Thus, my believing you might be thought a matter of my believing, perhaps, that what you say is true, and your belief in free-markets or in God, a matter of your believing that free-market economys are desirable or that God exists.

It is doubtful, however, that non-propositional believing can, in every case, be reduced in this way. Debate on this point has tended to focus on an apparent distinction between belief-that and belief-in, and the application of this distinction to belief in God. Some philosophers have followed Aquinas ©. 1225-74), in supposing that to believe in, and God is simply to believe that certain truths hold: That God exists, that he is benevolent, etc. Others (e.g., Hick, 1957) argue that belief-in is a distinctive attitude, one that includes essentially an element of trust. More commonly, belief-in has been taken to involve a combination of propositional belief together with some further attitude.

H.H. Price (1969) defends the claims that there are different sorts of belief-in, some, but not all, reducible to beliefs-that. If you believe in God, you believe that God exists, that God is good, etc., but, according to Price, your belief involves, in addition, a certain complex pro-attitude toward its object. One might attempt to analyse this further attitude in terms of additional beliefs-that: ‘S’ believes in ‘P’ just in case (1) ‘S’ believes that P exists (and perhaps holds further factual beliefs about (P): (2) ‘S’ believes that ‘P’ is good or valuable in some respect, and (3) ‘S’ believes that ‘P’s’ being good or valuable in this respect is itself is a good thing. An analysis of this sort, however, fails adequately to capture the further affective component of belief-in. Thus, according to Price, if you believe in God, your belief is not merely that certain truths hold, you posses, in addition, an attitude of commitment and trust toward God.

Notoriously, belief-in outruns the evidence for the corresponding belief-that. Does this diminish its rationality? If belief-in presupposes belief-that, it might be thought that the evidential standards for the former must be, at least as high as standards for the latter. And any additional pro-attitude might be thought to require a further layer of justification not required for cases of belief-that.

Some philosophers have argued that, at least for cases in which belief-in is synonymous with faith (or faith-in), evidential thresholds for constituent propositional beliefs are diminished. You may reasonably have faith in God or Mrs. Thatcher, even though beliefs about their respective attitudes, were you to harbour them, would be evidentially substandard.

Belief-in may be, in general, less susceptible to alternations in the face of unfavourable evidence than belief-that. A believer who encounters evidence against Gods existence may remain unshaken in his belief, in part because the evidence does not bear on his pro-attitude. So long as this is united with his belief that God exists, the belief may survive epistemic buffeting-and reasonably so in a way that an ordinary propositional belief-that would not.

At least two large sets of questions are properly treated under the heading of epistemological religious beliefs. First, there is a set of broadly theological questions about the relationship between faith and reason, between what one knows by way of reason, broadly construed, and what one knows by way of faith. These theological questions may as we call theological, because, of course, one will find them of interest only if one thinks that in fact there is such a thing as faith, and that we do know something by way of it. Secondly, there is a whole set of questions having to do with whether and to what degree religious beliefs have warrant, or justification, or positive epistemic status. The second, is seemingly as an important set of a theological question is yet spoken of faith.

Epistemology, so we are told, is theory of knowledge: Its aim is to discern and explain that quality or quantity enough of which distinguishes knowledge from mere true belief. We need a name for this quality or quantity, whatever precisely it is, call it warrant. From this point of view, the epistemology of religious belief should centre on the question whether religious belief has warrant, an if it does, hoe much it has and how it gets it. As a matter of fact, however, epistemological discussion of religious belief, at least since the Enlightenment (and in the Western world, especially the English-speaking Western world) has tended to focus, not on the question whether religious belief has warrant, but whether it is justified. More precisely, it has tended to focus on the question whether those properties enjoyed by theistic belief -the belief that there exists a person like the God of traditional Christianity, Judaism and Islam: An almighty Law Maker, or an all-knowing and most wholly benevolent and a loving spiritual person who has created the living world. The chief question, therefore, has ben whether theistic belief is justified, the same question is often put by asking whether theistic belief is rational or rationally acceptable. Still further, the typical way of addressing this question has been by way of discussing arguments for or and against the existence of God. On the pro side, there are the traditional theistic proofs or arguments: The ontological, cosmological and teleological arguments, using Kants terms for them. On the other side, the anti-theistic side, the principal argument is the argument from evil, the argument that is not possible or at least probable that there be such a person as God, given all the pain, suffering and evil the world displays. This argument is flanked by subsidiary arguments, such as the claim that the very concept of God is incoherent, because, for example, it is impossible that there are the people without a body, and Freudian and Marxist claims that religious belief arises out of a sort of magnification and projection into the heavens of human attributes we think important.

But why has discussion centred on justification rather than warrant? And precisely what is justification? And why has the discussion of justification of theistic belief focussed so heavily on arguments for and against the existence of God?

As to the first question, we can see why once we see that the dominant epistemological tradition in modern Western philosophy has tended to identify warrant with justification. On this way of looking at the matter, warrant, that which distinguishes knowledge from mere true belief, just is justification. Belief theory of knowledge-the theory according to which knowledge is justified true belief has enjoyed the status of orthodoxy. According to this view, knowledge is justified truer belief, therefore any of your beliefs have warrant for you if and only if you are justified in holding it.

But what is justification? What is it to be justified in holding a belief? To get a proper sense of the answer, we must turn to those twin towers of western epistemology. René Descartes and especially, John Locke. The first thing to see is that according to Descartes and Locke, there are epistemic or intellectual duties, or obligations, or requirements. Thus, Locke:

Faith is nothing but a firm assent of the mind, which if it is regulated, A is our duty, cannot be afforded to anything, but upon good reason: And cannot be opposite to it, he that believes, without having any reason for believing, may be in love with his own fanciers: But, neither seeks truth as he ought, nor pats the obedience due his maker, which would have him use those discerning faculties he has given him: To keep him out of mistake and error. He that does this to the best of his power, however, he sometimes lights on truth, is in the right but by chance: And I know not whether the luckiest of the accidents will excuse the irregularity of his proceeding. This, at least is certain, that he must be accountable for whatever mistakes he runs into: Whereas, he that makes use of the light and faculties God has given him, by seeks sincerely to discover truth, by those helps and abilities he has, may have this satisfaction in doing his duty as rational creature, that though he should miss truth, he will not miss the reward of it. For he governs his assent right, and places it as he should, who in any case or matter whatsoever, believes or disbelieves, according as reason directs him. He manages otherwise, transgresses against his own light, and misuses those faculties, which were given him . . . (Essays 4.17.24).

Rational creatures, creatures with reason, creatures capable of believing propositions (and of disbelieving and being agnostic with respect to them), say Locke, have duties and obligation with respect to the regulation of their belief or assent. Now the central core of the notion of justification(as the etymology of the term indicates) this: One is justified in doing something or in believing a certain way, if in doing one is innocent of wrong doing and hence not properly subject to blame or censure. You are justified, therefore, if you have violated no duties or obligations, if you have conformed to the relevant requirements, if you are within your rights. To be justified in believing something, then, is to be within your rights in so believing, to be flouting no duty, to be to satisfy your epistemic duties and obligations. This way of thinking of justification has been the dominant way of thinking about justification: And this way of thinking has many important contemporary representatives. Roderick Chisholm, for example (as distinguished an epistemologist as the twentieth century can boast), in his earlier work explicitly explains justification in terms of epistemic duty (Chisholm, 1977).

The (or, a) main epistemological; questions about religious believe, therefore, has been the question whether or not religious belief in general and theistic belief in particular is justified. And the traditional way to answer that question has been to inquire into the arguments for and against theism. Why this emphasis upon these arguments? An argument is a way of marshalling your propositional evidence-the evidence from other such propositions as likens to believe-for or against a given proposition. And the reason for the emphasis upon argument is the assumption that theistic belief is justified if and only if there is sufficient propositional evidence for it. If there is not much by way of propositional evidence for theism, then you are not justified in accepting it. Moreover, if you accept theistic belief without having propositional evidence for it, then you are ging contrary to epistemic duty and are therefore unjustified in accepting it. Thus, W.K. William James, trumpets that it is wrong, always everything upon insufficient evidence, his is only the most strident in a vast chorus of only insisting that there is an intellectual duty not to believe in God unless you have propositional evidence for that belief. A few others in the choir: Sigmund Freud, Brand Blanshard, H.H. Price, Bertrand Russell and Michael Scriven.)

Now how it is that the justification of theistic belief gets identified with there being propositional evidence for it? Justification is a matter of being blameless, of having done ones duty (in this context, ones epistemic duty): What, precisely, has this to do with having propositional evidence?

The answer, once, again, is to be found in Descartes especially Locke. As, justification is the property your beliefs have when, in forming and holding them, you conform to your epistemic duties and obligations. But according to Locke, a central epistemic duty is this: To believe a proposition only to the degree that it is probable with respect to what is certain for you. What propositions are certain for you? First, according to Descartes and Locke, propositions about your own immediate experience, that you have a mild headache, or that it seems to you that you see something red: And second, propositions that are self-evident for you, necessarily true propositions so obvious that you cannot so much as entertain them without seeing that they must be true. (Examples would be simple arithmetical and logical propositions, together with such propositions as that the whole is at least as large as the parts, that red is a colour, and that whatever exists has properties.) Propositions of these two sorts are certain for you, as fort other prepositions. You are justified in believing if and only if when one and only to the degree to which it is probable with respect to what is certain for you. According to Locke, therefore, and according to the whole modern Foundationalist tradition initiated by Locke and Descartes (a tradition that until has recently dominated Western thinking about these topics) there is a duty not to accept a proposition unless it is certain or probable with respect to what is certain.

In the present context, therefore, the central Lockean assumption is that there is an epistemic duty not to accept theistic belief unless it is probable with respect to what is certain for you: As a consequence, theistic belief is justified only if the existence of God is probable with respect to what is certain. Locke does not argue for his proposition, he simply announces it, and epistemological discussion of theistic belief has for the most part followed hin ion making this assumption. This enables us to see why epistemological discussion of theistic belief has tended to focus on the arguments for and against theism: On the view in question, theistic belief is justified only if it is probable with respect to what is certain, and the way to show that it is probable with respect to what it is certain are to give arguments for it from premises that are certain or, are sufficiently probable with respect to what is certain.

There are at least three important problems with this approach to the epistemology of theistic belief. First, there standards for theistic arguments have traditionally been set absurdly high (and perhaps, part of the responsibility for this must be laid as the door of some who have offered these arguments and claimed that they constitute wholly demonstrative proofs). The idea seems to test. a good theistic argument must start from what is self-evident and proceed majestically by way of self-evidently valid argument forms to its conclusion. It is no wonder that few if any theistic arguments meet that lofty standard -particularly, in view of the fact that almost no philosophical arguments of any sort meet it. (Think of your favourite philosophical argument: Does it really start from premisses that are self-evident and move by ways of self-evident argument forms to its conclusion?)

Secondly, attention has ben mostly confined to three theistic arguments: The traditional arguments, cosmological and teleological arguments, but in fact, there are many more good arguments: Arguments from the nature of proper function, and from the nature of propositions, numbers and sets. These are arguments from intentionality, from counterfactual, from the confluence of epistemic reliability with epistemic justification, from reference, simplicity, intuition and love. There are arguments from colours and flavours, from miracles, play and enjoyment, morality, from beauty and from the meaning of life. This is even a theistic argument from the existence of evil.

But there are a third and deeper problems here. The basic assumption is that theistic belief is justified only if it is or can be shown to be probable with respect to many a body of evidence or proposition - perhaps, those that are self-evident or about ones own mental life, but is this assumption true? The idea is that theistic belief is very much like a scientific hypothesis: It is acceptable if and only if there is an appropriate balance of propositional evidence in favour of it. But why believe a thing like that? Perhaps the theory of relativity or the theory of evolution is like that, such a theory has been devised to explain the phenomena and gets all its warrant from its success in so doing. However, other beliefs, e.g., memory beliefs, feelifelt in other minds is not like that, they are not hypothetical at all, and are not accepted because of their explanatory powers. There are instead, the propositions from which one start in attempting to give evidence for a hypothesis. Now, why assume that theistic belief, belief in God, is in this regard more like a scientific hypothesis than like, say, a memory belief? Why think that the justification of theistic belief depends upon the evidential relation of theistic belief to other things one believes? According to Locke and the beginnings of this tradition, it is because there is a duty not to assent to a proposition unless it is probable with respect to what is certain to you, but is there really any such duty? No one has succeeded in showing that, say, belief in other minds or the belief that there has been a past, is probable with respect to what is certain for us. Suppose it is not: Does it follow that you are living in epistemic sin if you believe that there are other minds? Or a past?

There are urgent questions about any view according to which one has duties of the sort do not believe p unless it is probable with respect to what is certain for you; . First, if this is a duty, is it one to which I can conform? My beliefs are for the most part not within my control: Certainly they are not within my direct control. I believe that there has been a past and that there are other people, even if these beliefs are not probable with respect to what is certain forms (and even if I came to know this) I could not give them up. Whether or not I accept such beliefs are not really up to me at all, For I can no more refrain from believing these things than I can refrain from conforming yo the law of gravity. Second, is there really any reason for thinking I have such a duty? Nearly everyone recognizes such duties as that of not engaging in gratuitous cruelty, taking care of ones children and ones aged parents, and the like, but do we also find ourselves recognizing that there is a duty not to believe what is not probable (or, what we cannot see to be probable) with respect to what are certain for us? It hardly seems so. However, it is hard to see why being justified in believing in God requires that the existence of God be probable with respect to some such body of evidence as the set of propositions certain for you. Perhaps, theistic belief is properly basic, i.e., such that one is perfectly justified in accepting it on the evidential basis of other propositions one believes.

Taking justification in that original etymological fashion, therefore, there is every reason ton doubt that one is justified in holding theistic belief only inf one is justified in holding theistic belief only if one has evidence for it. Of course, the term justification has under-gone various analogical extensions in the of various philosophers, it has been used to name various properties that are different from justification etymologically so-called, but anagogically related to it. In such a way, the term sometimes used to mean propositional evidence: To say that a belief is justified for someone is to saying that he has propositional evidence (or sufficient propositional evidence) for it. So taken, however, the question whether theistic belief is justified loses some of its interest; for it is not clear (given this use) beliefs that are unjustified in that sense. Perhaps, one also does not have propositional evidence for ones memory beliefs, if so, that would not be a mark against them and would not suggest that there be something wrong holding them.

Another analogically connected way to think about justification (a way to think about justification by the later Chisholm) is to think of it as simply a relation of fitting between a given proposition and ones epistemic vase -which includes the other things one believes, as well as ones experience. Perhaps tat is the way justification is to be thought of, but then, if it is no longer at all obvious that theistic belief has this property of justification if it seems as a probability with respect to many another body of evidence. Perhaps, again, it is like memory beliefs in this regard.

To recapitulate: The dominant Western tradition has been inclined to identify warrant with justification, it has been inclined to take the latter in terms of duty and the fulfilment of obligation, and hence to suppose that there is no epistemic duty not to believe in God unless you have good propositional evidence for the existence of God. Epistemological discussion of theistic belief, as a consequence, as concentrated on the propositional evidence for and against theistic belief, i.e., on arguments for and against theistic belief. But there is excellent reason to doubt that there are epistemic duties of the sort the tradition appeals to here.

And perhaps it was a mistake to identify warrant with justification in the first place. Napoleons have little warrant for him: His problem, however, need not be dereliction of epistemic duty. He is in difficulty, but it is not or necessarily that of failing to fulfill epistemic duty. He may be doing his epistemic best, but he may be doing his epistemic duty in excelsis: But his madness prevents his beliefs from having much by way of warrant. His lack of warrant is not a matter of being unjustified, i.e., failing to fulfill epistemic duty. So warrant and being epistemologically justified by name are not the same things. Another example, suppose (to use the favourite twentieth-century variant of Descartes evil demon example) I have been captured by Alpha-Centaurian super-scientists, running a cognitive experiment, they remove my brain, and keep it alive in some artificial nutrients, and by virtue of their advanced technology induce in me the beliefs I might otherwise have if I were going about my usual business. Then my beliefs would not have much by way of warrant, but would it be because I was failing to do my epistemic duty?

As a result of these and other problems, another, externalist way of thinking about knowledge has appeared in recent epistemology, that a theory of justification is internalized if and only if it requires that all of its factors needed for a belief to be epistemically accessible to that of a person, internal to his cognitive perception, and externalist, if it allows that, at least some of the justifying factors need not be thus accessible, in that they can be external to the believer s cognitive Perspectives, beyond his ken. However, epistemologists often use the distinction between internalized and externalist theories of epistemic justification without offering any very explicit explanation.

Or perhaps the thing to say, is that it has reappeared, for the dominant sprains in epistemology priori to the Enlightenment were really externalist. According to this externalist way of thinking, warrant does not depend upon satisfaction of duty, or upon anything else to which the Knower has special cognitive access (as he does to what is about his own experience and to whether he is trying his best to do his epistemic duty): It depends instead upon factors external to the epistemic agent -such factors as whether his beliefs are produced by reliable cognitive mechanisms, or whether they are produced by epistemic faculties functioning properly in-an appropriate epistemic environment.

How will we think about the epistemology of theistic belief in more than is less of an externalist way (which is at once both satisfyingly traditional and agreeably up to date)? I think, that the ontological question whether there is such a person as God is in a way priori to the epistemological question about the warrant of theistic belief. It is natural to think that if in fact we have been created by God, then the cognitive processes that issue in belief in God are indeed realisable belief-producing processes, and if in fact God created us, then no doubt the cognitive faculties that produce belief in God is functioning properly in an epistemologically congenial environment. On the other hand, if there is no such person as God, if theistic belief is an illusion of some sort, then things are much less clear. Then beliefs in God in of the most of basic ways of wishing that never doubt the production by which unrealistic thinking or another cognitive process not aimed at truth. Thus, it will have little or no warrant. And belief in God on the basis of argument would be like belief in false philosophical theories on the basis of argument: Do such beliefs have warrant? Notwithstanding, the custom of discussing the epistemological questions about theistic belief as if they could be profitably discussed independently of the ontological issue as to whether or not theism is true, is misguided. There two issues are intimately intertwined,

Nonetheless, the vacancy left, as today and as days before are an awakening and untold story beginning by some sparking conscious paradigm left by science. That is a central idea by virtue accredited by its epistemology, where in fact, is that justification and knowledge arising from the proper functioning of our intellectual virtues or faculties in an appropriate environment.

Finally, that the concerning mental faculty reliability point to the importance of an appropriate environment. The idea is that cognitive mechanisms might be reliable in some environments but not in others. Consider an example from Alvin Plantinga. On a planet revolving around Alfa Centauri, cats are invisible to human beings. Moreover, Alfa Centaurian cats emit a type of radiation that causes humans to form the belief that there I a dog barking nearby. Suppose now that you are transported to this Alfa Centaurian planet, a cat walks by, and you form the belief that there is a dog barking nearby. Surely you are not justified in believing this. However, the problem here is not with your intellectual faculties, but with your environment. Although your faculties of perception are reliable on earth, yet are unrealisable on the Alga Centaurian planet, which is an inappropriate environment for those faculties.

The central idea of virtue epistemology, as expressed in (J) above, has a high degree of initial plausibility. By masking the idea of faculties cental to the reliability if not by the virtue of epistemology, in that it explains quite neatly to why beliefs are caused by perception and memories are often justified, while beliefs caused by unrealistic and superstition are not. Secondly, the theory gives us a basis for answering certain kinds of scepticism. Specifically, we may agree that if we were brains in a vat, or victims of a Cartesian demon, then we would not have knowledge even in those rare cases where our beliefs turned out true. But virtue epistemology explains that what is important for knowledge is toast our faculties are in fact reliable in the environment in which we are. And so we do have knowledge so long as we are in fact, not victims of a Cartesian demon, or brains in a vat. Finally, Plantinga argues that virtue epistemology deals well with Gettier problems. The idea is that Gettier problems give us cases of justified belief that is truer by accident. Virtue epistemology, Plantinga argues, helps us to understand what it means for a belief to be true by accident, and provides a basis for saying why such cases are not knowledge. Beliefs are rue by accident when they are caused by otherwise reliable faculties functioning in an inappropriate environment. Plantinga develops this line of reasoning in Plantinga (1988).

The Humean problem if induction supposes that there is some property A pertaining to an observational or experimental situation, and that of A, some fraction m/n (possibly equal to 1) have also been instances of some logically independent property B. Suppose further that the background circumstances, have been varied to a substantial degree and that there is no collateral information available concerning the frequency of Bs among As or concerning causal nomological connections between instances of A and instances of B.

In this situation, an enumerative or instantial inductive inference would move from the premise that m/n of observed ‘A’s’ are ‘B’s’ to the conclusion that approximately m/n of all ‘A’s’ and ‘B’s’. (The usual probability qualification will be assumed to apply to the inference, than being part of the conclusion). Hereabouts the class of As should be taken to include not only unobservable As of future As, but also possible or hypothetical as. (An alternative conclusion would concern the probability or likelihood of the very next observed ‘A’ being a ‘B’).

The traditional or Humean problem of induction, often refereed to simply as the problem of induction, is the problem of whether and why inferences that fit this schema should be considered rationally acceptable or justified from an epistemic or cognitive standpoint, i.e., whether and why reasoning in this way is likely lead to true claims about the world. Is there any sort of argument or rationale that can be offered for thinking that conclusions reached in this way are likely to be true if the corresponding premiss is true or even that their chances of truth are significantly enhanced?

Humes discussion of this deals explicitly with cases where all observed ‘A’s’ are ‘B’s’, but his argument applies just as well to the more general casse. His conclusion is entirely negative and sceptical: inductive inferences are not rationally justified, but are instead the result of an essentially a-rational process, custom or habit. Hume challenges the proponent of induction to supply a cogent line of reasoning that leads from an inductive premise to the corresponding conclusion and offers an extremely influential argument in the form of a dilemma, to show that there can be no such reasoning. Such reasoning would, ne argues, have to be either deductively demonstrative reasoning concerning relations of ideas or experimental, i.e., empirical, reasoning concerning mattes of fact to existence. It cannot be the former, because all demonstrative reasoning relies on the avoidance of contradiction, and it is not a contradiction to suppose that the course of nature may change, tat an order that was observed in the past will not continue in the future: but it also cannot be the latter, since any empirical argument would appeal to the success of such reasoning in previous experiences, and the justifiability of generalizing from previous experience is precisely what is at issue - so that any such appeal would be question-begging, so then, there can be no such reasoning.

An alternative version of the problem may be obtained by formulating it with reference to the so-called Principle of Induction, which says roughly that the future will resemble or, that unobserved cases will reassembly observe cases. An inductive argument may be viewed as enthymematic, with this principle serving as a suppressed premiss, in which case the issue is obviously how such a premise can be justified. Humes argument is then that no such justification is possible: The principle cannot be justified speculatively as it is not contradictory to deny it: it cannot be justified by appeal to its having been true in pervious experience without obviously begging te question.

The predominant recent responses to the problem of induction, at least in the analytic tradition, in effect accept the main conclusion of Humes argument, viz. That inductive inferences cannot be justified I the sense of showing that the conclusion of such an inference is likely to be truer if the premise is true, and thus attempt to find some other sort of justification for induction.

Bearing upon, and if not taken into account the term induction is most widely used for any process of reasoning that takes us from empirical premises to empirical conclusions supported by the premise, but not deductively entailed by them. Inductive arguments are therefore kinds of amplicative argument, in which something beyond the content of the premises is inferred as probable or supported by them. Induction is, however, commonly distinguished from arguments to theoretical explanations, which share this amplicative character, by being confined to inference in which the conclusion involves the same properties or relations as the premises. The central example is induction by simple enumeration, where from premiss telling that ‘Fa’, ‘Fb’, ‘Fc’. , where ‘a’, ‘b’, ‘c’, are all of some kind ‘G’, It is inferred ‘G’s’ from outside the sample, such as future ‘G’s’ will be ‘F’, or perhaps other person deceive them, children may well infer that everyone is a deceiver. Different but similar inferences are those from the past possession of a property by some object to the same objects future possession, or from the constancy of some law-like pattern in events, and states of affairs to its future constancy: all objects we know of attract each the with a fore inversely proportional to the square of the distance between them, so perhaps they all do so, an will always do so.

The rational basis of any inference was challenged by David Hume (1711-76), who believed that induction of nature, and merely reflected a habit or custom of the mind. Hume was not therefore sceptical about the propriety of processes of inducting ion, but sceptical about the tole of reason in either explaining it or justifying it. trying to answer Hume and to show that there is something rationally compelling about the inference is referred to as the problem of induction. It is widely recognized that any rational defence of induction will have to partition well-behaved properties for which the inference is plausible (often called projectable properties) from badly behaved ones for which t is not. It is also recognized that actual inductive habits are more complex than those of simple and science pay attention to such factors as variations within the sample of giving us the evidence, the application of ancillary beliefs about the order of nature, and so on. Nevertheless, the fundamental problem remains that any experience shows us only events occurring within a very restricted part of the vast spatial temporal order about which we then come to believe things.

All the same, the classical problem of induction is often phrased in terms of finding some reason to expect that nature is uniform. In Fact, Fiction and Forecast (1954) Goodman showed that we need in addition some reason for preferring some uniformities to others, for without such a selection the uniformity of nature is vacuous. Thus, suppose that all examined emeralds have been green. Uniformity would lead us to expect that future emeralds will be green as well. But, now we define a predicate grue: is trued if and only if ‘x’ is examined before time ‘T’ and is green, or ‘P’ is examined after ‘T’ and is blue? Let ‘T’ refer to some time around the present. Then if newly examined emeralds are like previous ones in respect of being grue, they will be blue. We prefer blueness a basis of prediction to gluiness, but why?

Goodman argued that although his new predicate appears to be gerrymandered, and itself involves a reference to a difference, this is just aparohial or language-relative judgement, there being no language-independent standard of similarity to which to appeal. Other philosophers have not been convince by this degree of linguistic relativism. What remains clear that the possibility of these bent predicates put a decisive obstacle in face of purely logical and syntactical approaches to problems of confirmation?.

Both, Frége and Carnap, represented as analyticitys best friends in this century, did as much to undermine it as its worst enemies. Quine (1908-) whose early work was on mathematical logic, and issued in A System of Logistic (1934), Mathematical Logic (1940) and Methods of Logic (1950) it was with this collection of papers a Logical Point of View (1953) that his philosophical importance became widely recognized, also, Putman (1926-) his concern in the later period has largely been to deny any serious asymmetry between truth and knowledge as it is obtained in natural science, and as it is obtained in morals and even theology. Books include Philosophy of logic (1971), Representation and Reality (1988) and Renewing Philosophy (1992). Collections of his papers include Mathematics, Master, sand Method (1975), Mind, Language, and Reality (1975), and Realism and Reason (1983). Both of which represented as having refuted the analytic/synthetic distinction, not only did no such thing, but, in fact, contributed significantly to undoing the damage done by Frége and Carnap. Finally, the epistemological significance of the distinctions is nothing like what it is commonly taken to be.

Lockes account of an analyticity proposition as, for its time, everything that a succinct account of analyticity should be (Locke, 1924, pp. 306-8) he distinguished two kinds of analytic propositions, identified propositions in which we affirm the said terms if itself, e.g., Roses are roses, and predicative propositions in which a part of the complex idea is predicated of the name of the whole, e.g., Roses are flowers, Locke calls such sentences trifling because a speaker who uses them trifles with words. A synthetic sentence, in contrast, such as a mathematical theorem, states a truth and conveys with its informative real knowledge. Correspondingly, Locke distinguishes two kinds of necessary consequences, analytic entailment where validity depends on the literal containment of the conclusions in the premiss and synthetic entailments where it does not. (Locke did not originate this concept-containment notion of analyticity. It is discussions by Arnaud and Nicole, and it is safe to say it has been around for a very long time (Arnaud, 1964).

Kants account of analyticity, which received opinion tells us is the consummate formulation of this notion in modern philosophy, is actually a step backward. What is valid in his account is not novel, and what is novel is not valid. Kant presents Lockes account of concept-containment analyticity, but introduces certain alien features, the most important being his characterizations of most important being his characterization of analytic propositions as propositions whose denials are logical contradictions (Kant, 1783). This characterization suggests that analytic propositions based on Lockes part-whole relation or Kants explicative copula are a species of logical truth. But the containment of the predicate concept in the subject concept in sentences like Bachelors are unmarried is a different relation from containment of the consequent in the antecedent in a sentence like If John is a bachelor, then John is a bachelor or Mary read Kants Critique. The former is literal containment whereas, the latter are, in general, not. Talk of the containment of the consequent of a logical truth in the metaphorical, a way of saying logically derivable.

Kants conflation of concept containment with logical containment caused him to overlook the issue of whether logical truths are synthetically deductive and the problem of how he can say mathematical truths are synthetically deductive when they cannot be denied without contradiction. Historically. , the conflation set the stage for the disappearance of the Lockean notion. Frége, whom received opinion portrays as second only to Kant among the champions of analyticity, and Carnap, who it portrays as just behind Frége, was jointly responsible for the appearance of concept-containment analyticity.

Frége was clear about the difference between concept containment and logical containment, expressing it as like the difference between the containment of beams in a house the containment of a plant in the seed (Frége, 1853). But he found the former, as Kant formulated it, defective in three ways: It explains analyticity in psychological terms, it does not cover all cases of analytic propositions, and, perhaps, most important for Fréges logicism, its notion of containment is unfruitful as a definition; mechanisms in logic and mathematics (Frége, 1853). In an insidious containment between the two notions of containment, Frége observes that with logical containment we are not simply talking out of the box again what we have just put inti it. This definition makes logical containment the basic notion. Analyticity becomes a special case of logical truth, and, even in this special case, the definitions employ the power of definition in logic and mathematics than mere concept combination.

Carnap, attempting to overcome what he saw a shortcoming in Fréges account of analyticity, took the remaining step necessary to do away explicitly with Lockean-Kantian analyticity. As Carnap saw things, it was a shortcoming of Fréges explanation that it seems to suggest that definitional relations underlying analytic propositions can be extra-logic in some sense, say, in resting on linguistic synonymy. To Carnap, this represented a failure to achieve a uniform formal treatment of analytic propositions and left us with a dubious distinction between logical and extra-logical vocabulary. Hence, he eliminated the reference to definitions in Fréges of analyticity by introducing meaning postulates, e.g., statements such as ‘(œP)’ (‘P’ is a bachelor-is unmarried) (Carnap, 1965). Like standard logical postulate on which they were modelled, meaning postulates express nothing more than constrains on the admissible models with respect to which sentences and deductions are evaluated for truth and validity. Thus, despite their name, its asymptomatic-balance having to pustulate itself by that in what it holds on to not more than to do with meaning than any value-added statements expressing an indispensable truth. In defining analytic propositions as consequences of (an explained set of) logical laws, Carnap explicitly removed the one place in Fréges explanation where there might be room for concept containment and with it, the last trace of Lockes distinction between semantic and other necessary consequences.

Quine, the staunchest critic of analyticity of our time, performed an invaluable service on its behalf-although, one that has come almost completely unappreciated. Quine made two devastating criticism of Carnaps meaning postulate approach that expose it as both irrelevant and vacuous. It is irrelevant because, in using particular words of a language, meaning postulates fail to explicate analyticity for sentences and languages generally, that is, they do not define it for variables ‘S’ and ‘L’ (Quine, 1953). It is vacuous because, although meaning postulates tell us what sentences are to count as analytic, they do not tell us what it is for them to be analytic.

Received opinion gas it that Quine did much more than refute the analytic/synthetic distinction as Carnap tried to draw it. Received opinion has that Quine demonstrated there is no distinction, however, anyone might try to draw it. This, too, is incorrect. To argue for this stronger conclusion, Quine had to show that there is no way to draw the distinction outside logic, in particular theory in linguistic corresponding to Carnaps, Quines argument had to take an entirely different form. Some inherent feature of linguistics had to be exploited in showing that no theory in this science can deliver the distinction. But the feature Quine chose was a principle of operationalist methodology characteristic of the school of Bloomfieldian linguistics. Quine succeeds in showing that meaning cannot be made objective sense of in linguistics. If making sense of a linguistic concept requires, as that school claims, operationally defining it in terms of substitution procedures that employ only concepts unrelated to that linguistic concept. But Chomskys revolution in linguistics replaced the Bloomfieldian taxonomic model of grammars with the hypothetico-deductive model of generative linguistics, and, as a consequence, such operational definition was removed as the standard for concepts in linguistics. The standard of theoretical definition that replaced it was far more liberal, allowing the members of as family of linguistic concepts to be defied with respect to one another within a set of axioms that state their systematic interconnections -the entire system being judged by whether its consequences are confirmed by the linguistic facts. Quines argument does not even address theories of meaning based on this hypothetico-deductive model (Katz, 1988 and 1990).

Putman, the other staunch critic of analyticity, performed a service on behalf of analyticity fully on a par with, and complementary to Quines, whereas, Quine refuted Carnaps formalization of Fréges conception of analyticity, Putman refuted this very conception itself. Putman put an end to the entire attempt, initiated by Fridge and completed by Carnap, to construe analyticity as a logical concept (Putman, 1962, 1970, 1975).

However, as with Quine, received opinion has it that Putman did much more. Putman in credited with having devised science fiction cases, from the robot cat case to the twin earth cases, that are counter examples to the traditional theory of meaning. Again, received opinion is incorrect. These cases are only counter examples to Fréges version of the traditional theory of meaning. Fréges version claims both (1) that senses determines reference, and (2) that there are instances of analyticity, say, typified by cats are animals, and of synonymy, say typified by water in English and water in twin earth English. Given (1) and (2), what we call cats could not be non-animals and what we call water could not differ from what the earthier twin called water. But, as Putmans cases show, what we call cats could be Martian robots and what they call water could be something other than H2O Hence, the cases are counter examples to Fréges version of the theory.

The remaining Frégean criticism points to a genuine incompleteness of the traditional account of analyticity. There are analytic relational sentences, for example, Jane walks with those with whom she strolls, Jack kills those he

himself has murdered, etc., and analytic entailment with existential conclusions, for example, I think, therefore I exist. The containment in these sentences is just as literal as that in an analytic subject-predicate sentence like Bachelors are unmarried, such are shown to have a theory of meaning construed as a hypothetico-deductive systemisations of sense as defined in (D) overcoming the incompleteness of the traditional account in the case of such relational sentences.

Such a theory of meaning makes the principal concern of semantics the explanation of sense properties and relations like synonymy, an antonymy, redundancy, analyticity, ambiguity, etc. Furthermore, it makes grammatical structure, specifically, senses structure, the basis for explaining them. This leads directly to the discovery of a new level of grammatical structure, and this, in turn, makes possible a proper definition of analyticity. To see this, consider two simple examples. It is a semantic fact that a male bachelor is redundant and that single person is synonymous with woman who never married; . In the case of the redundancy, we have to explain the fact that the sense of the modifier male is already contained in the sense of its head bachelor. In the case of the synonymy, we have to explain the fact that the sense of sinister is identical to the sense of woman who never married (compositionally formed from the senses of woman, never and married). But is so fas as such facts concern relations involving the components of the senses of bachelor and spinster and is in as far as these words are syntactic simple, there must be a level of grammatical structure at which syntactic simple are semantically complex. This, in brief, is the route by which we arrive a level of decompositional semantic structure; that is the locus of sense structures masked by syntactically simple words.

Once, again, the fact that (A) itself makes no reference to logical operators or logical laws indicate that analyticity for subject-predicate sentences can be extended to simple relational sentences without treating analytic sentences as instances of logical truths. Further, the source of the incompleteness is no longer explained, as Fridge explained it, as the absence of fruitful logical apparatus, but is now explained as mistakenly treating what is only a special case of analyticity as if it were the general case. The inclusion of the predicate in the subject is the special case (where n = 1) of the general case of the inclusion of an–place predicate (and its terms) in one of its terms. Noting that the defects, by which, Quine complained of in connection with Carnaps meaning-postulated explication are absent in (A). (A) contains no words from a natural language. It explicitly uses variable ‘S’ and variable ‘L’ because it is a definition in linguistic theory. Moreover, (A) tell us what property is in virtue of which a sentence is analytic, namely, redundant predication, that is, the predication structure of an analytic sentence is already found in the content of its term structure.

Received opinion has been anti-Lockean in holding that necessary consequences in logic and language belong to one and the same species. This seems wrong because the property of redundant predication provides a non-logic explanation of why true statements made in the literal use of analytic sentences are necessarily true. Since the property ensures that the objects of the predication in the use of an analytic sentence are chosen on the basis of the features to be predicated of them, the truth-conditions of the statement are automatically satisfied once its terms take on reference. The difference between such a linguistic source of necessity and the logical and

mathematical sources vindicate Lockes distinction between two kinds of necessary consequence.

Received opinion concerning analyticity contains another mistake. This is the idea that analyticity is inimical to science, in part, the idea developed as a reaction to certain dubious uses of analyticity such as Fréges attempt to establish logicism and Schlicks, Ayers and other logical; postivists attempt to deflate claims to metaphysical knowledge by showing that alleged deductive truths are merely empty analytic truths (Schlick, 1948, and Ayer, 1946). In part, it developed as also a response to a number of cases where alleged analytic, and hence, necessary truths, e.g., the law of excluded a seeming next-to-last subsequent to have been taken as open to revision, such cases convinced philosophers like Quine and Putnam that the analytic/synthetic distinction is an obstacle to scientific progress.

The problem, if there is, one is one is not analyticity in the concept-containment sense, but the conflation of it with analyticity in the logical sense. This made it seem as if there is a single concept of analyticity that can serve as the grounds for a wide range of deductive truths. But, just as there are two analytic/synthetic distinctions, so there are two concepts of concept. The narrow Lockean/Kantian distinction is based on a narrow notion of expressions on which concepts are senses of expressions in the language. The broad Frégean/Carnap distinction is based on a broad notion of concept on which concepts are conceptions -often scientific one about the nature of the referent (s) of expressions (Katz, 1972) and curiously Putman, 1981). Conflation of these two notions of concepts produced the illusion of a single concept with the content of philosophical, logical and mathematical conceptions, but with the status of linguistic concepts. This encouraged philosophers to think that they were in possession of concepts with the contentual representation to express substantive philosophical claims, e.g., such as Fridge, Schlick and Ayers, . . . and so on, and with a status that trivializes the task of justifying them by requiring only linguistic grounds for the deductive propositions in question.

Finally, there is an important epistemological implication of separating the broad and narrowed notions of analyticity. Fridge and Carnap took the broad notion of analyticity to provide foundations for necessary and a priority, and, hence, for some form of rationalism, and nearly all rationalistically inclined analytic philosophers followed them in this. Thus, when Quine dispatched the Frége-Carnap position on analyticity, it was widely believed that necessary, as a priority, and rationalism had also been despatched, and, as a consequence. Quine had ushered in an empiricism without dogmas and naturalized epistemology. But given there is still a notion of analyticity that enables us to pose the problem of how necessary, synthetic deductive knowledge is possible (moreover, one whose narrowness makes logical and mathematical knowledge part of the problem), Quine did not under-cut the foundations of rationalism. Hence, a serious reappraisal of the new empiricism and naturalized epistemology is, to any the least, is very much in order (Katz, 1990).

In some areas of philosophy and sometimes in things that are less than important we are to find in the deductively/inductive distinction in which has been applied to a wide range of objects, including concepts, propositions, truths and knowledge. Our primary concern will, however, be with the epistemic distinction between deductive and inductive knowledge. The most common way of marking the distinction is by reference to Kants claim that deductive knowledge is absolutely independent of all experience. It is generally agreed that Ss knowledge that p is independent of experience just in case Ss belief that p is justified independently of experience. Some authors (Butchvarov, 1970, and Pollock, 1974) are, however, in finding this negative characterization of deductive unsatisfactory knowledge and have opted for providing a positive characterisation in terms of the type of justification on which such knowledge is dependent. Finally, others (Putman, 1983 and Chisholm, 1989) have attempted to mark the distinction by introducing concepts such as necessity and rational unrevisability than in terms of the type of justification relevant to deductive knowledge.

One who characterizes deductive knowledge in terms of justification that is independent of experience is faced with the task of articulating the relevant sense of experience, and proponents of the deductive ly cites intuition or intuitive apprehension as the source of deductive justification. Furthermore, they maintain that these terms refer to a distinctive type of experience that is both common and familiar to most individuals. Hence, there is a broad sense of experience in which deductive justification is dependent of experience. An initially attractive strategy is to suggest that theoretical justification must be independent of sense experience. But this account is too narrow since memory, for example, is not a form of sense experience, but justification based on memory is presumably not deductive. There appear to remain only two options: Provide a general characterization of the relevant sense of experience or enumerates those sources that are experiential. General characterizations of experience often maintain that experience provides information specific to the actual world while non-experiential sources provide information about all possible worlds. This approach, however, reduces the concept of non-experiential justification to the concept of being justified in believing a necessary truth. Accounts by enumeration have two problems (1) there is some controversy about which sources to include in the list, and (2) there is no guarantee that the list is complete. It is generally agreed that perception and memory should be included. Introspection, however, is problematic, and beliefs about ones conscious states and about the manner in which one is appeared to are plausible regarded as experientially justified. Yet, some, such as Pap (1958), maintain that experiments in imagination are the source of deductive justification. Even if this contention is rejected and deductive justification is characterized as justification independent of the evidence of perception, memory and introspection, it remains possible that there are other sources of justification. If it should be the case that clairvoyance, for example, is a source of justified beliefs, such beliefs would be justified deductively on the enumerative account.

The most common approach to offering a positive characterization of deductive justification is to maintain that in the case of basic deductive propositions, understanding the proposition is sufficient to justify one in believing that it is true. This approach faces two pressing issues. What is it to understand a proposition in the manner that suffices for justification? Proponents of the approach typically distinguish understanding the words used to express a proposition from apprehending the proposition itself and maintain that it is the latter which are relevant to deductive justification. But this move simply shifts the problem to that of specifying what it is to apprehend a proposition. Without a solution to this problem, it is difficult, if possible, to evaluate the account since one cannot be sure that the account since on cannot be sure that the requisite sense of apprehension does not justify paradigmatic inductive propositions as well. Even less is said about the manner in which apprehending a proposition justifies one in believing that it is true. Proponents are often content with the bald assertions that one who understands a basic deductive proposition can thereby see that it is true. But what requires explanation is how understanding a proposition enable one to see that it is true.

Difficulties in characterizing deductive justification in a term either of independence from experience or of its source have led, out-of-the-ordinary to present the concept of necessity into their accounts, although this appeal takes various forms. Some have employed it as a necessary condition for deductive justification, others have employed it as a sufficient condition, while still others have employed it as both. In claiming that necessity is a criterion of the deductive. Kant held that necessity is a sufficient condition for deductive justification. This claim, however, needs further clarification. There are three theses regarding the relationship between the theoretically and the necessary that can be distinguished: (I) if p is a necessary proposition and ‘S’ is justified in believing that ‘p’ is necessary, then ‘S’s’ justification is deductive: (ii) If ‘p’ is a necessary proposition and ‘S’ is justified in believing that ‘p’ is necessarily true, then ‘S’s’ justification is deductive: And (iii) If ‘p’ is a necessary proposition and ‘S’ is justfied in believing that ‘p’, then ‘S’s’ justification is deductive. For example, many proponents of deductive contend that all knowledge of a necessary proposition is deductive. (2) and (3) have the shortcoming of setting by stipulation the issue of whether inductive knowledge of necessary propositions is possible. (I) does not have this shortcoming since the recent examples offered in support of this claim by Kriple (1980) and others have been cases where it is alleged that knowledge of the truth value of necessary propositions is knowable inductive. (I) has the shortcoming, however, of either ruling out the possibility of being justified in believing that a proposition is necessary on the basis of testimony or else sanctioning such justification as deductive. (ii) and (iii), of course, suffer from an analogous problem. These problems are symptomatic of a general shortcoming of the approach: It attempts to provide a sufficient condition for deductive justification solely in terms of the modal status of the proposition believed without making reference to the manner in which it is justified. This shortcoming, however, can be avoided by incorporating necessity as a necessary but not sufficient condition for a prior justification as, for example, in Chisholm (1989). Here there are two theses that must be distinguished: (1) If ‘S’ is justified deductively in believing that ‘p’, then p is necessarily true. (2) If ‘p’ is justified deductively in believing that ‘p’. Then ‘p’ is a necessary proposition. (1) and (2), however, allows this possibility. A further problem with both (1) and (2) is that it is not clear whether they permit deductively justified beliefs about the modal status of a proposition. For they require that in order for ‘S’ to be justified deductively in believing that ‘p’ is a necessary preposition it must be necessary that p is a necessary proposition. But the status of iterated modal propositions is controversial. Finally, (1) and (2) both preclude by stipulation the position advanced by Kripke (1980) and Kitcher (1980) that there is deductive knowledge of contingent propositions.

The concept of rational unrevisability has also been invoked to characterize deductive justification. The precise sense of rational unrevisability has been presented in different ways. Putnam (1983) takes rational unrevisability to be both a necessary and sufficient condition for deductive justification while Kitcher (1980) takes it to be only a necessary condition. There are also two different senses of rational unrevisability that have been associated with the deductive (I) a proposition is weakly unreviable just in case it is rationally unrevisable in light of any future experiential evidence, and (II) a proposition is strongly unrevisable just in case it is rationally unrevisable in light of any future evidence. Let us consider the plausibility of requiring either form of rational unrevisability as a necessary condition for deductive justification. The view that a proposition is justified deductive only if it is strongly unrevisable entails that if a non-experiential source of justified beliefs is fallible but self-correcting, it is not a deductive source of justification. Casullo (1988) has argued that it vis implausible to maintain that a proposition that is justified non-experientially is not justified deductively merely because it is revisable in light of further non-experiential evidence. The view that a proposition is justified deductively only if it is, weakly unrevisable is not open to this objection since it excludes only recession in light of experiential evidence. It does, however, face a different problem. To maintain that ‘S’s’ justified belief that ‘p’ is justified deductively is to make a claim about the type of evidence that justifies ‘S’ in believing that ‘p’. On the other hand, to maintain that ‘S’s’ justified belief that p is rationally revisable in light of experiential evidence is to make a claim about the type of evidence that can defeat ‘S’s’ justification for believing that p that a claim about the type of evidence that justifies ‘S’ in believing that ‘p’. Hence, it has been argued by Edidin (1984) and Casullo (1988) that to hold that a belief is justified deductively only if it is weakly unrevisable is either to confuse supporting evidence with defeating evidence or to endorse some implausible this about the relationship between the two such as that if evidence of the sort as the kind ‘A’ can defeat the justification conferred on ‘S’s belief that ‘p’ by evidence of kind ‘B’ then ‘S’s’ justification for believing that ‘p’ is based on evidence of kind ‘A’.

The most influential idea in the theory of meaning in the past hundred years is the thesis that the meaning of an indicative sentence is given by its truth-conditions. On this conception, to understand a sentence is to know its truth-conditions. The conception was first clearly formulated by Fridge, was developed in a distinctive way by the early Wittgenstein, and is a leading idea of Donald Herbert Davidson (1917-), who is also known for rejection of the idea of as conceptual scheme, thought of as something peculiar to one language or one way of looking at the world, arguing that where the possibility of translation stops so dopes the coherence of the idea that there is anything to translate. His [papers are collected in the Essays on Actions and Events (1980) and Inquiries into Truth and Interpretation (1983). However, the conception has remained so central that those who offer opposing theories characteristically define their position by reference to it.

Wittgensteins main achievement is a uniform theory of language that yields an explanation of logical truth. A factual sentence achieves sense by dividing the possibilities exhaustively into two groups, those that would make it true and those that would make it false. A truth of logic does not divide the possibilities but comes out true in all of them. It, therefore, lacks sense and says nothing, but it is not nonsense. It is a self-cancellation of sense, necessarily true because it is a tautology, the limiting case of factual discourse, like the figure ‘0' in mathematics. Language takes many forms and even factual discourse does not consist entirely of sentences like The fork is placed to the left of the knife. However, the first thing that he gave up was the idea that this sentence itself needed further analysis into basic sentences mentioning simple objects with no internal structure. He was to concede, that a descriptive word will often get its meaning partly from its place in a system, and he applied this idea to colour-words, arguing that the essential relations between different colours do not indicate that each colour has an internal structure that needs to be taken apart. On the contrary, analysis of our colour-words would only reveal the same pattern-ranges of incompatible properties-recurring at every level, because that is how we carve up the world.

Indeed, it may even be the case that of our ordinary language is created by moves that we ourselves make. If so, the philosophy of language will lead into the connection between the meaning of a word and the applications of it that its users intend to make. There is also an obvious need for people to understand each others meanings of their words. There are many links between the philosophy of language and the philosophy of mind and it is not surprising that the impersonal examination of language in the Tractatus: was replaced by a very different, anthropocentric treatment in Philosophical Investigations?

If the logic of our language is created by moves that we ourselves make, various kinds of realises are threatened. First, the way in which our descriptive language carves up the world will not be forces on us by the natures of things, and the rules for the application of our words, which feel the external constraints, will really come from within us. That is a concession to nominalism that is, perhaps, readily made. The idea that logical and mathematical necessity is also generated by what we ourselves accomplish what is more paradoxical. Yet, that is the conclusion of Wittgenstein (1956) and (1976), and here his anthropocentricism has carried less conviction. However, a paradox is not sure of error and it is possible that what is needed here is a more sophisticated concept of objectivity than Platonism provides.

In his later work Wittgenstein brings the great problem of philosophy down to earth and traces them to very ordinary origins. His examination of the concept of following a rule takes him back to a fundamental question about counting things and sorting them into types: What qualifies as doing the same again? Of a courser, this question as an inconsequential fundamental and would suggest that we forget it and get on with the subject. But Wittgensteins question is not so easily dismissed. It has the naive profundity of questions that children ask when they are first taught a new subject. Such questions remain unanswered without detriment to their learning, but they point the only way to complete understanding of what is learned.

It is, nevertheless, the meaning of a complex expression in a function of the meaning of its constituents, that is, indeed, that it is just a statement of what it is for an expression to be semantically complex. It is one of the initial attractions of the conception of meaning as truths-conditions that it permits a smooth and satisfying account of the way in which the meaning of a complex expression is a dynamic function of the meaning of its constituents. On the truth-conditional conception, to give the meaning of an expression is to state the contribution it makes to the truth-conditions of sentences in which it occurs. for singular terms-proper names, indexicals, and certain pronouns -this is done by stating the reference of the term in question.

The truth condition of a statement is the condition the world must meet if the statement is to be true. To know this condition is equivalent to knowing the meaning of the statement. Although, this sounds as if it gives a solid anchorage for meaning, some of the security disappears when it turns out that the truth condition can only be defined by repeating the very same statement, the truth condition of snow is white is that snow is white, the truth condition of Britain would have capitulated had Hitler invaded is that Britain would halve capitulated had Hitler invaded. It is disputed whether this element of running-on-the-spot disqualifies truth conditions from playing the central role in a substantive theory of meaning. Truth-conditional theories of meaning are sometimes opposed by the view that to know the meaning of a statement is to be able to users it in a network of inferences.

























































The theorist of truth conditions should insist that not every true statement about the reference of an expression be fit to be an axiom in a meaning-giving theory of truth for a language. The axiom:

London refers to the city in which there was a huge fire in 1666

is a true statement about the reference of London?. It is a consequence of a theory that substitutes this axiom for A! In our simple truth theory that London is beautiful is true if and only if the city in which there was a huge fire in 1666 is beautiful. Since a subject can understand the name London without knowing that last-mentioned truth conditions, this replacement axiom is not fit to be an axiom in a meaning-specifying truth theory. It is, of course, incumbent on a theorist of meaning as truth conditions to state the constraints on the acceptability of axioms in a way that does not presuppose a deductive, non-truth conditional conception of meaning.

Among the many challenges facing the theorist of truth conditions, two are particularly salient and fundamental. First, the theorist has to answer the charge of triviality or vacuity. Second, the theorist must offer an account of what it is for a persons language to be truly descriptive by a semantic theory containing a given semantic axiom.

We can take the charge of triviality first. In more detail, it would run thus: Since the content of a claim that the sentence Paris is beautiful in which is true of the divisional region, which is no more than the claim that Paris is beautiful, we can trivially describe understanding a sentence, if we wish, as knowing its truth-conditions, but this gives us no substantive account of understanding whatsoever. Something other than a grasp to truth conditions must provide the substantive account. The charge rests upon what has been called the redundancy theory of truth, the theory that, is somewhat more discriminative. Horwich calls the minimal theory of truth, or deflationary view of truth, as fathered by Fridge and Ramsey. The essential claim is that the predicate . . . is true does not have a sense, i.e., expresses no substantive or profound or explanatory concepts that ought be the topic of philosophical enquiry. The approach admits of different versions, but centres on the points (1) that it is true that p says no more nor less than p (hence redundancy) (2) that in less direct context, such as everything he said was true, or all logical consequences of true propositions are true, the predicate functions as a device enabling us; to generalize than as an adjective or predicate describing the thing he said, or the kinds of propositions that follow from true propositions. For example, the second may translate as (œ p, q) (p & p ÿ q ÿq) where there is no use of a notion of truth.

There are technical problems in interpreting all uses of the notion of truth in such ways, but they are not generally felt to be insurmountable. The approach needs to explain away apparently substantive uses of the notion, such of a science aims at the truth, or truth is a norm governing discourse. Indeed, postmodernist writing frequently advocates that we must abandon such norms, along with a discredited objective conception of truth. But perhaps, we can have the norms even when objectivity is problematic, since they can be framed without mention of truth: Science wants it to be so that whenever science holds that ‘p’. Then ‘p’. Discourse is to be regulated by the principle that it is wrong to assert ‘p’ when ‘not-p’.

The disquotational theory of truth finds that the simplest formulation is the claim that expressions of the formed ‘S’ is true mean the same as expressions of the form ‘S’. Some philosophers dislike the idea of sameness of meaning, and if this is disallowed, then the claim is that the two forms are equivalent in any sense of equivalence that matters. That is, it makes no difference whether people say Dogs bark is true, or whether they say that dogs bark. In the former representation of what they say the sentence Dogs bark is mentioned, but in the latter it appears to be used, so the claim that the two are equivalent needs careful formulation and defence. On the face of it someone might know that Dogs bark is true without knowing what it means, for instance, if one were to find it in a list of acknowledged truths, although he does not understand English, and this is different from knowing that dogs bark. Disquotational theories are usually presented as versions of the redundancy theory of truth.

The minimal theory states that the concept of truth is exhausted by the fact that it conforms to the equivalence principle, the principle that for any proposition ‘p’, it is true that ‘p’ if and only if ‘p’. Many different philosophical theories of truth will, with suitable qualifications, accept that equivalence principle. The distinguishing feature of the minimal theory is its claim that the equivalence principle exhausts the notion of truths. It is how widely accepted, that both by opponents and supporters of truth conditional theories of meaning, that it is inconsistent to accept both minimal theory of truth and a truth conditional account of meaning (Davidson, 1990, Dummett, 1959 and Horwich, 1990). If the claim that the sentence Paris is beautiful is true is exhausted by its equivalence to the claim that Paris is beautiful, it is circular to try to explain the sentences meaning in terms of its truth conditions. The minimal theory of truth has been endorsed by Ramsey, Ayer, the later Wittgenstein, Quine, Strawson, Horwich and-confusingly and inconsistently if be it correct-Fridge himself. But is the minimal theory correct?

The minimal or redundancy theory treats instances of the equivalence principle as definitional of truth for a given sentence. But in fact, it seems that each instance of the equivalence principle can itself be explained. The truths from which such an instance as: London is beautiful is true if and only if London is beautiful, preserve a right to be interpreted specifically of this would be a pseudo-explanation if the fact that London refers to London is beautiful has the truth-condition it does. But that is very implausible: It is, after all, possible to understand the name London without understanding the predicate is beautiful. The idea that facts about the reference of particular words can be explanatory of facts about the truth conditions of sentences containing them in no way requires any naturalistic or any other kind of reduction of the notion of reference. Nor is the idea incompatible with the plausible point that singular reference can be attributed at all only to something that is capable of combining with other expressions to form complete sentences. That still leaves room for facts about an expressions having the particular reference it does to be partially explanatory of the particular truth condition possessed by a given sentence containing it. The minimal; theory thus treats as definitional or stimulative something that is in fact open to explanation. What makes this explanation possible is that there is a general notion of truth that has, among the many links that hold it in place, systematic connections with the semantic values of sub-sentential expressions.

A second problem with the minimal theory is that it seems impossible to formulate it without at some point relying implicitly on features and principles involving truths that go beyond anything countenanced by the minimal theory. If the minimal theory treats truth as a predicate of anything linguistic, be it utterances, type-in-a-language, or whatever, then the equivalence schema will not cover all cases, but only those in the theorists own language. Some account has to be given of truth for sentences of other languages. Speaking of the truth of language-independence propositions or thoughts will only postpone, not avoid, this issue, since at some point principles have to be stated associating these language-independent entities with sentences of particular languages. The defender of the minimalist theory is likely to say that if a sentence ‘S’ of a foreign language is best translated by our sentence ‘p’, then the foreign sentence ‘S’ is true if and only if ‘p’. Now the best translation of a sentence must preserve the concepts expressed in the sentence. Constraints involving a general notion of truth are persuasive in a plausible philosophical theory of concepts. It is, for example, a condition of adequacy on an individualized account of any concept that there exists what is called Determination Theory for that account-that is, a specification of how the account contributes to fixing the semantic value of that concept, the notion of a concepts semantic value is the notion of something that makes a certain contribution to the truth conditions of thoughts in which the concept occurs. but this is to presuppose, than to elucidate, a general notion of truth.

It is also plausible that there are general constraints on the form of such Determination Theories, constraints that involve truth and which are not derivable from the minimalists conception. Suppose that concepts are individuated by their possession conditions. A concept is something that is capable of being a constituent of such contentual representational in a way of thinking of something-a particular object, or property, or relation, or another entity. A possession condition may in various says makes a thankers possession of a particular concept dependent upon his relations to his environment. Many possession conditions will mention the links between a concept and the thinkers perceptual experience. Perceptual experience represents the world for being a certain way. It is arguable that the only satisfactory explanation of what it is for perceptual experience to represent the world in a particular way must refer to the complex relations of the experience to the subjects environment. If this is so, then mention of such experiences in a possession condition will make possession of that condition will make possession of that concept dependent in part upon the environment relations of the thinker. Burge (1979) has also argued from intuitions about particular examples that, even though the thinkers non-environmental properties and relations remain constant, the conceptual content of his mental state can vary if the thinkers social environment is varied. A possession condition which property individuates such a concept must take into account the thinkers social relations, in particular his linguistic relations.

One such plausible general constraint is then the requirement that when a thinker forms beliefs involving a concept in accordance with its possession condition, a semantic value is assigned to the concept in such a way that the belief is true. Some general principles involving truth can indeed, as Horwich has emphasized, be derived from the equivalence schema using minimal logical apparatus. Consider, for instance, the principle that Paris is beautiful and London is beautiful is true if and only if Paris is beautiful is true if and only if Paris is beautiful is true and London is beautiful is true. This follows logically from the three instances of the equivalence principle: Paris is beautiful and London is beautiful is rue if and only if Paris is beautiful, and London is beautiful is true if and only if London is beautiful. But no logical manipulations of the equivalence schemas will allow the deprivation of that general constraint governing possession conditions, truth and the assignment of semantic values. That constraint can have courses be regarded as a further elaboration of the idea that truth is one of the aims of judgement.

We now turn to the other question, What is it for a persons language to be correctly describable by a semantic theory containing a particular axiom, such as the axiom A6 above for conjunction? This question may be addressed at two depths of generality. At the shallower level, the question may take for granted the persons possession of the concept of conjunction, and be concerned with what has to be true for the axiom correctly to describe his language. At a deeper level, an answer should not duck the issue of what it is to possess the concept. The answers to both questions are of great interest: We will take the lesser level of generality first.

When a person means conjunction by sand, he is not necessarily capable of formulating the explicitly of the axiom. Even if he can formulate it, his ability to formulate it is not the causal basis of his capacity to hear sentences containing the word and as meaning something involving conjunction. Nor is it the causal basis of his capacity to mean something involving conjunction by sentences he utters containing the word and. Is it then right to regard a truth theory as part of an unconscious psychological computation, and to regard understanding a sentence as involving a particular way of depriving a theorem from a truth theory at some level of conscious proceedings? One problem with this is that it is quite implausible that everyone who speaks the same language has to use the same algorithms for computing the meaning of a sentence. In the past thirteen years, thanks particularly to the work of Davies and Evans, a conception has evolved according to which an axiom is true of a persons language only if there is a common component in the explanation of his understanding of each sentence containing the word and, a common component that explains why each such sentence is understood as meaning something involving conjunction (Davies, 1987). This conception can also be elaborated in computational terms: Suggesting that for an axiom to be true of a persons language is for the unconscious mechanisms which produce understanding to draw on the information that a sentence of the form ‘A’ and ‘B’ are true if and only if ‘A’ is true and ‘B’ is true (Peacocke, 1986). Many different algorithms may equally draw n this information. The psychological reality of a semantic theory thus involves, in Marrs (1982) famous classification, something intermediate between his level one, the function computed, and his level two, the algorithm by which it is computed. This conception of the psychological reality of a semantic theory can also be applied to syntactic and phonol logical theories. Theories in semantics, syntax and phonology are not themselves required to specify the particular algorithms that the language user employs. The identification of the particular computational methods employed is a task for psychology. But semantics, syntactic and phonology theories are answerable to psychological data, and are potentially refutable by them-for these linguistic theories do make commitments to the information drawn upon by mechanisms in the language user.

This answer to the question of what it is for an axiom to be true of a persons language clearly takes for granted the persons possession of the concept expressed by the word treated by the axiom. In the example of the axiom A6, the information drawn upon is that sentences of the form ‘A’ and ‘B’ are true if and only if ‘A’ is true and ‘B’ is true. This informational content employs, as it has to if it is to be adequate, the concept of conjunction used in stating the meaning of sentences containing and. So the computational answer we have returned needs further elaboration if we are to address the deeper question, which does not want to take for granted possession of the concepts expressed in the language. It is at this point that the theory of linguistic understanding has to draws upon a theory of concepts. It is plausible that the concepts of conjunction are individuated by the following condition for a thinker to possess it.

Finally, this response to the deeper question allows us to answer two challenges to the conception of meaning as truth-conditions. First, there was the question left hanging earlier, of how the theorist of truth-conditions is to say what makes one axiom of a semantic theory is correctly in that of another, when the two axioms assign the same semantic values, but do so by means of different concepts. Since the different concepts will have different possession conditions, the dovetailing accounts, at the deeper level of what it is for each axiom to be correct for a persons language will be different accounts. Second, there is a challenge repeatedly made by the minimalist theorists of truth, to the effect that the theorist of meaning as truth-conditions should give some non-circular account of what it is to understand a sentence, or to be capable of understanding all sentences containing a given constituent. For each expression in a sentence, the corresponding dovetailing account, together with the possession condition, supplies a non-circular account of what it is to understand any sentence containing that expression. The combined accounts for each of he expressions that comprise a given sentence together constitute a non-circular account of what it is to understand the compete sentences. Taken together, they allow the theorists of meaning as truth-conditions fully to meet the challenge.

A curious view common to that which is expressed by an utterance or sentence: The proposition or claim made about the world. By extension, the content of a predicate or other sub-sentential component is what it contributes to the content of sentences that contain it. The nature of content is the central concern of the philosophy of language, in that mental states have contents: A belief may have the content that the prime minister will resign. A concept is something that is capable of bringing a constituent of such contents.

Several different concepts may each be ways of thinking of the same object. A person may think of himself in the first-person way, or think of himself as the spouse of Mary Smith, or as the person located in a certain room now. More generally, a concept c is distinct from a concept d if it is possible for a person rationally to believe d is such-and-such. As words can be combined to form structured sentences, concepts have also been conceived as combinable into structured complex contents. When these complex contents are expressed in English by that . . . clauses, as in our opening examples, they will be capable of being true or false, depending on the way the world is.

The general system of concepts with which we organize our thoughts and perceptions are to encourage a conceptual scheme of which the outstanding elements of our every day conceptual formalities include spatial and temporal relations between events and enduring objects, causal relations, other persons, meaning-bearing utterances of others, . . . and so on. To see the world as containing such things is to share this much of our conceptual scheme. A controversial argument of Davidsons’ urges that we would be unable to interpret speech from a different conceptual scheme as even meaningful, Davidson daringly goes on to argue that since translation proceeds according ti a principle of clarity, and since it must be possible of an omniscient translator to make sense of, us we can be assured that most of the beliefs formed within the commonsense conceptual framework are true.

Concepts are to be distinguished from a stereotype and from conceptions. The stereotypical spy may be a middle-level official down on his luck and in need of money. None the less, we can come to learn that Anthony Blunt, art historian and Surveyor of the Queens Pictures, are a spy; we can come to believe that something falls under a concept while positively disbelieving that the same thing falls under the stereotype associated wit the concept. Similarly, a persons conception of a just arrangement for resolving disputes may involve something like contemporary Western legal systems. But whether or not it would be correct, it is quite intelligible for someone to rejects this conception by arguing that it dies not adequately provide for the elements of fairness and respect that are required by the concepts of justice.

Basically, a concept is that which is understood by a term, particularly a predicate. To posses a concept is to be able to deploy a term expressing it in making judgements, in which the ability connection is such things as recognizing when the term applies, and being able to understand the consequences of its application. The term idea was formally used in the came way, but is avoided because of its associations with subjective matters inferred upon mental imagery in which may be irrelevant to the possession of a concept. In the semantics of Fridge, a concept is the reference of a predicate, and cannot be referred to by a subjective term, although its recognition of as a concept, in that some such notion is needed to the explanatory justification of which that sentence of unity finds of itself from being thought of as namely categorized lists of itemized priorities.

A theory of a particular concept must be distinguished from a theory of the object or objects it selectively picks the outlying of the theory of the concept under which is partially contingent of the theory of thought and/or epistemology. A theory of the object or objects is part of metaphysics and ontology. Some figures in the history of philosophy-and are open to the accusation of not having fully respected the distinction between the kinds of theory. Descartes appears to have moved from facts about the indubitability of the thought I think, containing the fist-person was of thinking, to conclusions about the nonmaterial nature of the object he himself was. But though the goals of a theory of concepts and a theory of objects are distinct, each theory is required to have an adequate account of its relation to the other theory. A theory if concept is unacceptable if it gives no account of how the concept is capable of picking out the object it evidently does pick out. A theory of objects is unacceptable if it makes it impossible to understand how we could have concepts of those objects.

A fundamental question for philosophy is: What individuates a given concept-that is, what makes it the one it is, rather than any other concept? One answer, which has been developed in great detail, is that it is impossible to give a non-trivial answer to this question (Schiffer, 1987). An alternative approach, addressees the question by starting from the idea that a concept id individuated by the condition that must be satisfied if a thinker is to posses that concept and to be capable of having beliefs and other attitudes whose content contains it as a constituent. So, to take a simple case, one could propose that the logical concept and is individuated by this condition, it be the unique concept ‘C’ to posses that a thinker has to find these forms of inference compelling, without basing them on any further inference or information: From any two premisses ‘A’ and ‘B’, ‘ACB’ can be inferred, and from any premiss ‘ACB’, each of ‘A’ and ‘B’ can be inferred. Again, a relatively observational concept such as round can be individuated in part by stating that the thinker finds specified contents containing it compelling when he has certain kinds of perception, and in part by relating those judgements containing the concept and which are not based on perception to those judgements that are. A statement that individuates a concept by saying what is required for a thinker to posses it can be described as giving the possession condition for the concept.

A possession condition for a particular concept may actually make use of that concept. The possession condition for and does so. We can also expect to use relatively observational concepts in specifying the kind of experience that have to be mentioned in the possession conditions for relatively observational concepts. What we must avoid is mention of the concept in question as such within the content of the attitudes attributed to the thinker in the possession condition. Otherwise we would be presupposing possession of the concept in an account that was meant to elucidate its possession. In talking of what the thinker finds compelling, the possession conditions can also respect an insight of the later Wittgenstein: That to find her finds it natural to go on in new cases in applying the concept.

Sometimes a family of concepts has this property: It is not possible to master any one of the members of the family without mastering the others. Two of the families that plausibly have this status are these: The family consisting of some simple concepts 0, 1, 2, . . . of the natural numbers and the corresponding concepts of numerical quantifiers there are 0 so-and-so, there is 1 so-and-so, . . . and the family consisting of the concepts; belief and desire. Such families have come to be known as local holism. A local holism does not prevent the individuation of a concept by its possession condition. Rather, it demands that all the concepts in the family be individuated simultaneously. So one would say something of this form: Belief and desire form the unique pair of concepts C1 and C2 such that for as thinker to posses them are to meet such-and-such condition involving the thinker, C1 and C2. For these and other possession conditions to individuate properly, it is necessary that there be some ranking of the concepts treated. The possession conditions for concepts higher in the ranking must presuppose only possession of concepts at the same or lower levels in the ranking.

A possession conditions may in various ways make a thinkers possession of a particular concept dependent upon his relations to his environment. Many possession conditions will mention the links between a concept and the thinkers perceptual experience. Perceptual experience represents the world as a certain way. It is arguable that the only satisfactory explanation of what it is for perceptual experience to represent the world in a particular way must refer to the complex relations of the experience to the subjects environment. If this is so, then mention of such experiences in a possession condition will make possession of that concept dependent in part upon the environmental relations of the thinker. Burge (1979) has also argued from intuitions about particular examples that, even though the thinkers non-environmental properties and relations remain constant, the conceptual content of his mental state can vary if the thinkers social environment is varied. A possession condition that properly individuates such a concept must take into account the thinkers social relations, in particular his linguistic relations.

Concepts have a normative dimension, a fact strongly emphasized by Kripke. For any judgement whose content involves a given concept, there is a correctness condition for that judgement, a condition that is dependent in part upon the identity of the concept. The normative character of concepts also extends into making the territory of a thinkers reasons for making judgements. A thinkers visual perception can give him good reason for judging That man is bald: It does not by itself give him good reason for judging Rostropovich ids bald, even if the man he sees is Rostropovich. All these normative connections must be explained by a theory of concepts one approach to these matters is to look to the possession condition for the concept, and consider how the referent of a concept is fixed from it, together with the world. One proposal is that the referent of the concept is that object or, property, or function, . . . which makes the practices of judgement and inference mentioned in the possession condition always lead to true judgements and truth-preserving inferences. This proposal would explain why certain reasons are necessity good reasons for judging given contents. Provided the possession condition permits us to say what it is about a thinkers previous judgements that masker it, the case that he is employing one concept rather than another, this proposal would also have another virtue. It would allow us to say how the correctness condition is determined for a judgement in which the concept is applied to newly encountered objects. The judgement is correct if the new object has the property that in fact makes the judgmental practices mentioned in the possession condition yield true judgements, or truth-preserving inferences.

These manifesting dissimilations have occasioned the affiliated differences accorded within the distinction as associated with Leibniz, who declares that there are only two kinds of truths-truths of reason and truths of fact. The forms are all either explicit identities, i.e., of the form ‘A’ is ‘A’, ‘AB’ is ‘B’, etc., or they are reducible to this form by successively substituting equivalent terms. Leibniz dubs them truths of reason because the explicit identities are self-evident deducible truths, whereas the rest can be converted to such by purely rational operations. Because their denial involves a demonstrable contradiction, Leibniz also says that truths of reason rest on the principle of contradiction, or identity and that they are necessary [propositions, which are true of all possible words. Some examples are All equilateral rectangles are rectangles and All bachelors are unmarried: The first is already of the form ‘AB’ is ‘B’ and the latter can be reduced to this form by substituting unmarried man fort bachelor. Other examples, or so Leibniz believes, are God exists and the truths of logic, arithmetic and geometry.

Truths of fact, on the other hand, cannot be reduced to an identity and our only way of knowing them is empirically by reference to the facts of the empirical world. Likewise, since their denial does not involve a contradiction, their truth is merely contingent: They could have been otherwise and hold of the actual world, but not of every possible one. Some examples are Caesar crossed the Rubicon and Leibniz was born in Leipzig, as well as propositions expressing correct scientific generalizations. In Leibnizs view, truths of fact rest on the principle of sufficient reason, which states that nothing can be so unless there is a reason that it is so. This reason is that the actual world (by which he means the total collection of things past, present and future) is better than any other possible worlds and was therefore created by God.

In defending the principle of sufficient reason, Leibniz runs into serious problems. He believes that in every true proposition, the concept of the predicate is contained in that of the subject. (This holds even for propositions like Caesar crossed the Rubicon: Leibniz thinks anyone who dids not cross the Rubicon, would not have been Caesar). And this containment relationship! Which is eternal and unalterable even by God ~? Guarantees that every truth has a sufficient reason. If truths consists in concept containment, however, then it seems that all truths are analytic and hence necessary, and if they are all necessary, surely they are all truths of reason. Leibnitz responds that not every truth can be reduced to an identity in a finite number of steps, in some instances revealing the connection between subject and predicate concepts would requite an infinite analysis. But while this may entail that we cannot prove such propositions as deductively manifested, it does not appear to show that the proposition could have been false. Intuitively, it seems a better ground for supposing that it is necessary truth of a special sort. A related question arises from the idea that truths of fact depend on Gods decision to creates the best of all possible worlds: If it is part of the concept of this world that it is best, now could its existence be other than necessary? Leibniz answers that its existence is only hypothetically necessary, i.e., it follows from Gods decision to create this world, but God had the power to decide otherwise. Yet God is necessarily good and non-deceiving, so how could he have decided to do anything else? Leibniz says much more about these masters, but it is not clear whether he offers any satisfactory solutions.

Leibniz and others have thought of truths as a property of propositions, where the latter are conceived as things that may be expressed by, but are distinct from, linguistic items like statements. On another approach, truth is a property of linguistic entities, and the basis of necessary truth in convention. Thus A.J. Ayer, for example,. Argued that the only necessary truths are analytic statements and that the latter rest entirely on our commitment to use words in certain ways.

The slogan the meaning of a statement is its method of verification expresses the empirical verifications theory of meaning. It is more than the general criterion of meaningfulness if and only if it is empirically verifiable. If says in addition what the meaning of a sentence is: It is all those observations that would confirm or disconfirmed the sentence. Sentences that would be verified or falsified by all the same observations are empirically equivalent or have the same meaning. A sentence is said to be cognitively meaningful if and only if it can be verified or falsified in experience. This is not meant to require that the sentence be conclusively verified or falsified, since universal scientific laws or hypotheses (which are supposed to pass the test) are not logically deducible from any amount of actually observed evidence.

When one predicates necessary truth of a preposition one speaks of modality dedicto. For one ascribes the modal property, necessary truth, to a dictum, namely, whatever proposition is taken as necessary. A venerable tradition, however, distinguishes this from necessary de re, wherein one predicates necessary or essential possession of some property to an on object. For example, the statement ‘4' is necessarily greater than ‘2' might be used to predicate of the object, ‘4', the property, being necessarily greater than ‘2'. That objects have some of their properties necessarily, or essentially, and others only contingently, or accidentally, are a main part of the doctrine called; essentialism. Thus, an essentials might say that Socrates had the property of being bald accidentally, but that of being self-identical, or perhaps of being human, essentially. Although essentialism has been vigorously attacked in recent years, most particularly by Quine, it also has able contemporary proponents, such as Plantinga.

Modal necessity as seen by many philosophers whom have traditionally held that every proposition has a modal status as well as a truth value. Every proposition is either necessary or contingent as well as either true or false. The issue of knowledge of the modal status of propositions has received much attention because of its intimate relationship to the issue of deductive reasoning. For example, no propositions of the theoretic content that all knowledge of necessary propositions is deductively knowledgeable. Others reject this claim by citing Kripkes (1980) alleged cases of necessary theoretical propositions. Such contentions are often inconclusive, for they fail to take into account the following tripartite distinction: ‘S’ knows the general modal status of ‘p’ just in case ‘S’ knows that ‘p’ is a necessary proposition or ‘S’ knows the truth that ‘p’ is a contingent proposition. ‘S’ knows the truth value of ‘p’ just in case ‘S’ knows that ‘p’ is true or ‘S’ knows that ‘p’ is false. ‘S’ knows the specific modal status of ‘p’ just in case ‘S’ knows that ‘p’ is necessarily true or ‘S’ knows that ‘p’ is necessarily false or ‘S’ knows that ‘p’ is contingently true or ‘S’ knows that ‘p’ is contingently false. It does not follow from the fact that knowledge of the general modal status of a proposition is a deductively reasoned distinctive modal status is also given to theoretical principles. Nor des it follow from the fact that knowledge of a specific modal status of a proposition is theoretically given as to the knowledge of its general modal status that also is deductive.

The certainties involving reason and a truth of fact are much in distinction by associative measures given through Leibniz, who declares that there are only two kinds of truths-truths of reason and truths of fact. The former are all either explicit identities, i.e., of the form ‘A’ is ‘A’, ‘AB’ is ‘B’, etc., or they are reducible to this form by successively substituting equivalent terms. Leibniz dubs them truths of reason because the explicit identities are self-evident theoretical truth, whereas the rest can be converted to such by purely rational operations. Because their denial involves a demonstrable contradiction, Leibniz also says that truths of reason rest on the principle of contraction, or identity and that they are necessary propositions, which are true of all possible worlds. Some examples are that All bachelors are unmarried: The first is already of the form ‘AB’ is ‘B’ and the latter can be reduced to this form by substituting unmarried man for bachelor. Other examples, or so Leibniz believes, are God exists and the truth of logic, arithmetic and geometry.

Truths of fact, on the other hand, cannot be reduced to an identity and our only way of knowing hem os a theoretical manifestations, or by reference to the fact of the empirical world. Likewise, since their denial does not involve as contradiction, their truth is merely contingent: They could have been otherwise and hold of the actual world, but not of every possible one. Some examples are Caesar crossed the Rubicon and Leibniz was born in Leipzig, as well as propositions expressing correct scientific generalizations. In Leibnizs view, truths of fact rest on the principle of sufficient reason, which states that nothing can be so unless thee is a reason that it is so. This reason is that the actual world (by which he means the total collection of things past, present and future) is better than any other possible world and was therefore created by God.

In defending the principle of sufficient reason, Leibniz runs into serious problems. He believes that in every true proposition, the concept of the predicate is contained in that of the subject. (This hols even for propositions like Caesar crossed the Rubicon: Leibniz thinks anyone who did not cross the Rubicon would not have been Caesar) And this containment relationship-that is eternal and unalterable even by God-guarantees that every truth has a sufficient reason. If truth consists in concept containment, however, then it seems that all truths are analytic and hence necessary, and if they are all necessary, surely they are all truths of reason. Leibniz responds that not evert truth can be reduced to an identity in a finite number of steps: In some instances revealing the connection between subject and predicate concepts would require an infinite analysis. But while this may entail that we cannot prove such propositions as deductively probable, it does not appear to show that the proposition could have been false. Intuitively, it seems a better ground for supposing that it is a necessary truth of a special sort. A related question arises from the idea that truths of fact depend on Gods decision to create the best world, if it is part of the concept of this world that it is best, how could its existence be other than necessary? Leibniz answers that its existence is only hypothetically necessary, i.e., it follows from Gods decision to create this world, but God is necessarily good, so how could he have decided to do anything else? Leibniz says much more about the matters, but it is not clear whether he offers any satisfactory solutions.

The modality of a proposition is the way in which it is true or false. The most important division is between propositions true of necessity, and those true as a things are: Necessary as opposed to contingent propositions. Other qualifiers sometimes called modal include the tense indicators It will be the case that ‘p’ or It was the case that ‘p’, and there are affinities between the deontic indicators, as it ought to be the case that ‘p’ or it is permissible that ‘p’, and the logical modalities as a logic that study the notions of necessity and possibility. Modal logic was of a great importance historically, particularly in the light of various doctrines concerning the necessary properties of the deity, but was not a central topic of modern logic in its golden period at the beginning of the 20th century. It was, however, revived by C. I. Lewis, by adding to a propositional or predicate calculus two operators, G and  (sometimes written N and M), meaning necessarily and possibly, respectively. These like p !  p and G p ! p will be to include G p ! GG p , if a proposition is necessary, and  p ! G  p, if a proposition is possible. The classical modal theory for modal logic, due to Kripke and the Swedish logician Stig Kanger, involves valuing propositions not as true or false simplicitiers, but as true or false art possible worlds, with necessity then corresponding to truth in all worlds, and possibly to truths in some world.

The doctrine advocated by David Lewis, which different possible worlds are to be thought of as existing exactly as this one does. Thinking in terms of possibilities is thinking of real worlds where things are different, this view has been charged with misrepresenting it as some insurmountably unseeing to why it is good to save the child from drowning, since there is still a possible world in which she (or her counterpart) drowned, and from the standpoint of the universe it should make no difference that world is actual. Critics asio charge either that the notion fails to fit with a coherent theory of how we know about possible worlds, or with a coherent theory about possible worlds, or with a coherent theory of why we are interested in them, but Lewis denies that any other way of interpreting modal statements is tenable.



Knowledge and belief, according to most epistemologists, knowledge entails belief, so that I cannot know that such and such is the case unless I believe that such and such is the case. Others think this entailment thesis can be rendered more accurately if we substitute for belief some closely related attitude. For instance, several philosophers would prefer to say that knowledge entail psychological certainties (Prichard, 1950 and Ayer, 1956) or conviction (Lehrer, 1974) or acceptance (Lehrer, 1989). None the less, there are arguments against all versions of the thesis that knowledge requires having a belief-like attitude toward the known. These arguments are given by philosophers who think that knowledge and belief (or a facsimile) are mutually incompatible (the incomparability thesis), or by ones who say that knowledge does not entail belief, or vice versa, so that each may exist without the other, but the two may also coexist (the separability thesis).

The incompatibility thesis is sometimes traced to Plato, 429-347 Bc in view of his claim that knowledge is infallible while belief or opinion is fallible (Republic 476-9). But this claim would not support the thesis. Belief might be a component of an infallible form of knowledge in spite of the fallibility of belief. Perhaps, knowledge involves some factor that compensates for the fallibility of belief.

A. Duncan-Jones (1939: Also Vendler, 1978) cite linguistic evidence to back up the incompatibility thesis. He notes that people often say I do not believe she is guilty. I know she is and the like, which suggest that belief rule out knowledge. However, as Lehrer (1974) indicates, the above exclamation is only a more emphatic way of saying I do not just believe she is guilty, I know she is where just makes it especially clear that the speaker is signalling that she has something more salient than mere belief, not that she has something inconsistent with belief, namely knowledge. Compare: You do not hurt him, you killed him.

A. Prichard (1966) offers a defence of the incompatibility thesis that hinges on the equation of knowledge with certainty (both infallibility and psychological certitude) and the assumption that when we believe in the truth of a claim we are not certain about its truth. Given that belief always involves uncertainty while knowledge never dies, believing something rules out the possibility of knowing it. Unfortunately, however, Prichard gives us no goods reason to grant that states of belief are never ones involving confidence. Conscious beliefs clearly involve some level of confidence, to suggest that we cease to believe things about which we are completely confident is bizarre.

A.D. Woozley (1953) defends a version of the separability thesis. Woozleys version, which deals with psychological certainty rather than belief per se, is that knowledge can exist in the absence of confidence about the item known, although might also be accompanied by confidence as well. Woozley remarks that the test of whether I know something is what I can do, where what I can do may include answering questions. On the basis of this remark he suggests that even when people are unsure of the truth of a claim, they might know that the claim is true. We unhesitatingly attribute knowledge to people who give correct responses on examinations even if those people show no confidence in their answers. Woozley acknowledges, however, that it would be odd for those who lack confidence to claim knowledge. It would be peculiar to say, I am unsure whether my answer is true: Still, I know it is correct. But this tension Woozley explains using a distinction between conditions under which we are justified in making a claim (such as a claim to know something), and conditions under which the claim we make is true. While I know such and such might be true even if I am unsure whether such and such holds, nonetheless it would be inappropriate for me to claim that I know that such and such unless I were sure of the truth of my claim.

Colin Radford (1966) extends Woozleys defence of the separability thesis. In Radfords view, not only is knowledge compatible with the lack of certainty, it is also compatible with a complete lack of belief. He argues by example. In one example, Jean has forgotten that he learned some English history years priori and yet he is able to give several correct responses to questions such as When did the Battle of Hastings occur? Since he forgot that he took history, he considers the correct response to be no more than guesses. Thus, when he says that the Battle of Hastings took place in 1066 he would deny having the belief that the Battle of Hastings took place in 1066. A disposition he would deny being responsible (or having the right to be convincing) that 1066 was the correct date. Radford would none the less insist that Jean know when the Battle occurred, since clearly be remembering the correct date. Radford admits that it would be inappropriate for Jean to say that he knew when the Battle of Hastings occurred, but, like Woozley he attributes the impropriety to a fact about when it is and is not appropriate to claim knowledge. When we claim knowledge, we ought, at least to believe that we have the knowledge we claim, or else our behaviour is intentionally misleading.

Those that agree with Radfords defence of the separability thesis will probably think of belief as an inner state that can be detected through introspection. That Jean lacks beliefs about English history is plausible on this Cartesian picture since Jean does not find himself with any beliefs about English history when ne seek them out. One might criticize Radford, however, by rejecting that Cartesian view of belief. One could argue that some beliefs are thoroughly unconscious, for example. Or one could adopt a behaviourist conception of belief, such as Alexander Bains (1859), according to which having beliefs is a matter of the way people are disposed to behave (and has not Radford already adopted a behaviourist conception of knowledge?) Since Jean gives the correct response when queried, a form of verbal behaviour, a behaviourist would be tempted to credit him with the belief that the Battle of Hastings occurred in 1066.

D.M. Armstrong (1873) takes a different tack against Radford. Jean does know that the Battle of Hastings took place in 1066. Armstrong will grant Radfod that point, in fact, Armstrong suggests that Jean believe that 1066 is not the date the Battle of Hastings occurred, for Armstrong equates the belief that such and such is just possible but no more than just possible with the belief that such and such is not the case. However, Armstrong insists, Jean also believes that the Battle did occur in 1066. After all, had Jean been mistaught that the Battle occurred in 1066, and subsequently guessed that it took place in 1066, we would surely describe the situation as one in which Jeans false belief about the Battle became unconscious over time but persisted of a memory trace that was causally responsible for his guess. Out of consistency, we must describe Radfords original case as one that Jeans true belief became unconscious but persisted long enough to cause his guess. Thus, while Jean consciously believes that the Battle did not occur in 1066, unconsciously he does believe it occurred in 1066. So after all, Radford does not have a counterexample to the claim that knowledge entails belief.

Armstrongs response to Radford was to reject Radfords claim that the examinee lacked the relevant belief about English history. Another response is to argue that the examinee lacks the knowledge Radford attributes to him (cf. Sorenson, 1982). If Armstrong is correct in suggesting that Jean believes both that 1066 is and that it is not the date of the Battle of Hastings, one might deny Jean knowledge on the grounds that people who believe the denial of what they believe cannot be said to’ know the truth of their belief. Another strategy might be to compare the examine case with examples of ignorance given in recent attacks on externalist accounts of knowledge (needless to say. Externalists themselves would tend not to favour this strategy). Consider the following case developed by BonJour (1985): For no apparent reason, Samantha believes that she is clairvoyant. Again, for no apparent reason, she one day comes to believe that the President is in New York City, even though she has every reason to believe that the President is in Washington, D.C. In fact, Samantha is a completely reliable clairvoyant, and she has arrived at her belief about the whereabouts of the President thorough the power of her clairvoyance. Yet surely Samanthas belief is completely irrational. She is not justified in thinking what she does. If so, then she does not know where the President is. But Radfords examinee is unconventional. Even if Jean lacks the belief that Radford denies him, Radford does not have an example of knowledge that is unattended with belief. Suppose that Jeans memory had been sufficiently powerful to produce the relevant belief. As Radford says, in having every reason to suppose that his response is mere guesswork, and he has every reason to consider his belief false. His belief would be an irrational one, and hence one about whose truth Jean would be ignorant.

Least has been of mention to an approaching view from which perception basis upon itself as a fundamental philosophical topic both for its central place in a theory of knowledge, and its central place un any theory of consciousness. Philosophy in this area is constrained by a number of properties that we believe to hold of perception, (1) It gives us knowledge of the world around us. (2) We are conscious of that world by being aware of sensible qualities: Colour, sounds, tastes, smells, felt warmth, and the shapes and positions of objects in the environment. (3) Such consciousness is effected through highly complex information channels, such as the output of the three different types of colour-sensitive cells in the eye, or the channels in the ear for interpreting pulses of air pressure as frequencies of sound. (4) There ensues even more complex neurophysiological coding of that information, and eventually higher-order brain functions bring it about that we interpreted the information so received. (Much of this complexity has been revealed by the difficulties of writing programs enabling computers to recognize quite simple aspects of the visual scene.) The problem is to avoid thinking of here being a central, ghostly, conscious self, fed information in the same way that a screen if fed information by a remote television camera. Once such a model is in place, experience will seem like a veil getting between us and the world, and the direct objects of perception will seem to be private items in an inner theatre or sensorium. The difficulty of avoiding this model is epically cute when we considered the secondary qualities of colour, sound, tactile feelings and taste, which can easily seem to have a purely private existence inside the perceiver, like sensation of pain. Calling such supposed items names like sense-data or percepts exacerbates the tendency, but once the model is in place, the first property, that perception gives us knowledge of the world and its surrounding surfaces, is quickly threatened, for there will now seem little connection between these items in immediate experience and any independent reality. Reactions to this problem include scepticism and idealism.

A more hopeful approach is to claim that the complexities of (3) and (4) explain how we can have direct acquaintance of the world, than suggesting that the acquaintance we do have been at best indirect. It is pointed out that perceptions are not like sensation, precisely because they have a content, or outer-directed nature. To have a perception is to be aware of the world for being such-and-such a way, than to enjoy a mere modification of sensation. But such direct realism has to be sustained in the face of the evident personal (neurophysiological and other) factors determining haw we perceive. One approach is to ask why it is useful to be conscious of what we perceive, when other aspects of our functioning work with information determining responses without any conscious awareness or intervention. A solution to this problem would offer the hope of making consciousness part of the natural world, than a strange optional extra.

Furthering, perceptual knowledge is knowledge acquired by or through the senses and includes most of what we know. We cross intersections when we see the light turn green, head for the kitchen when we smell the roast burning, squeeze the fruit to determine its ripeness, and climb out of bed when we hear the alarm ring. In each case we come to know something-that the light has turned green, that the roast is burning, that the melon is overripe, and that it is time to get up-by some sensory means. Seeing that the light has turned green is learning something-that, the light has turned green-by use of the eyes. Feeling that the melon is overripe is coming to know a fact-that the melon is overripe-by ones sense to touch. In each case the resulting knowledge is somehow based on, derived from or grounded in the sort of experience that characterizes the sense modality in question.

Much of our perceptual knowledge is indirect, dependent or derived. By this I mean that the facts we describe ourselves as learning, as coming to know, by perceptual means are pieces of knowledge that depend on our coming to know something else, some other fact, in a more direct way. We see, by the gauge, that we need gas, see, by the newspapers, that our team has lost again, see, by her expression, that she is nervous. This derived or dependent sort of knowledge is particularly prevalent in the cases of vision, but it occurs, to a lesser degree, in every sense modality. We install bells and other noise-makers so that we calm for example, hear (by the bell) that someone is at the door and (by the alarm) that its time to get up. When we obtain knowledge in this way, it is clear that unless one can see, hence, comes to know something about the gauge (that it says) and, hence, know that one is described as coming to know by perceptual means. If one cannot hear that the bell is ringing, one cannot-in at least in this way-hear that ones visitors have arrived. In such cases one sees (hears, smells, etc.) that ‘a’ is ‘F’, coming to know thereby that ‘a’ is ‘F’, by seeing (hearing, etc.) that some other condition, ‘b’s’ being ‘G’, obtains when this occurs, the knowledge (that a is F) is derived from, or dependent on, the more basic perceptual knowledge that ‘b’ is ‘G’.

Perhaps as a better strategy is to tie an account save that part that evidence could justify explanation for it is its truth alone. Since, at least the time of Aristotle philosophers of explanatory knowledge have emphasizes of its importance that, in its simplest therms, we want to know not only what are the composite peculiarities and particulars points of issue but also why it is. This consideration suggests that we define an explanation as an answer to a why-question. Such a definition would, however, be too broad, because some why-questions are requests for consolation (Why did my son have to die?) Or moral justification (Why should women not be paid the same as men for the same work?) It would also be too narrow because some explanations are responses to how-questions (How does radar work?) Or how-possibility-questions (How is it possible for cats always to land their feet?)

In its overall sense, to explain means to make clear, to make plain, or to provide understanding. Definition of this sort are philosophically unhelpful, for the terms used in the deficient are no less problematic than the term to be defined. Moreover, since a wide variety of things require explanation, and since many different types of explanation exist, as more complex explanation is required. To facilitate the requirement leaves, least of mention, for us to consider by introduction a bit of technical terminology. The term explanation is used to refer to that which is to be explained: The term explanans refers to that which does the explaining, the explanans and the explanation taken together constitute the explanation.

One common type of explanation occurs when deliberate human actions are explained in terms of conscious purposes. Why did you go to the pharmacy yesterday? Because I had a headache and needed to get some aspirin. It is tacitly assumed that aspirin is an appropriate medication for headaches and that going t the pharmacy would bean efficient way of getting some. Such explanations are, of course, teleological, referring, ss they do, to goals. The explanans is not the realisation of a future goal - if the pharmacy happened to be closed for stocktaking the aspirin would have ben obtained there, bu t that would not invalidate the explanation. Some philosophers would say that the antecedent desire to achieve the end is what doers the explaining: Others might say that the explaining is done by the nature of the goal and the fact that the action promoted the chances of realizing it. (Taylor, 1964). In that it should not be automatically be assumed that such explanations are causal. Philosophers differ considerably on whether these explanations are to be framed in terms of cause or reason, but the distinction cannot be used to show that the relation between reasons and the actions they justify is in no way causal, and there are many differing analyses of such concepts as intention and agency. Expanding the domain beyond consciousness, Freud maintained, in addition, that much human behaviour can be explained in terms of unconscious and conscious wishes. Those Freudian explanations should probably be construed as basically causal.

Problems arise when teleological explanations are offered in other context. The behaviour of non-human animals is often explained in terms of purpose, e.g., the mouse ran to escape from the cat. In such cases the existence of conscious purpose seems dubious. The situation is still more problematic when a supr-empirical purpose in invoked -, e.g., the explanations of living species in terms of Gods purpose, or the vitalistic explanations of biological phenomena in terms of a entelechy or vital principle. In recent years an anthropic principle has received attention in cosmology (Barrow and Tipler, 1986). All such explanations have been condemned by many philosophers an anthropomorphic.

Nevertheless, philosophers and scientists often maintain that functional explanations play an important an legitimate role in various sciences such as, evolutionary biology, anthropology and sociology. For example, of the peppered moth in Liverpool, the change in colour from the light phase to the dark phase and back again to the light phase provided adaption to a changing environment and fulfilled the function of reducing predation on the spacies. In the study of primitive soviets anthropologists have maintained that various rituals the (rain dance) which may be inefficacious in braining about their manifest gaols (producing rain), actually cohesion at a period of stress (often a drought). Philosophers who admit teleological and/or functional explanations in common sense and science oftentimes take pans to argue that such explanations can be annualized entirely in terms of efficient causes, thereby escaping the charge of anthropomorphism (Wright, 1976): Again, however, not all philosophers agree.

Mainly to avoid the incursion of unwanted theology, metaphysics, or anthropomorphism into science, many philosophers and scientists, especially during the first half of the twentieth century - held that science provides only descriptions and predictions of natural phenomena, but not explanations for a series of influential philosophers of science - including Karl Popper (1935) Carl Hempel and Paul Oppenheim (1948) and Hempel (1965) - maintained that empirical science can explain natural phenomena without appealing to metaphysics or theology. It appears that this view is now accepted by the vast majority of philosophers of science, though there is sharp disagreement on the nature of scientific explanation.

The foregoing approach, developed by Hempel, Popper and others, became virtually a received view in the 1960s and 1970s. According to this view, to give a scientific explanation of any natural phenomenon is to show how this phenomena can be subsumed under a law of nature. A particular repture in a water pipe can be explained by citing the universal law that water expands when it freezes and the fact that the temperature of water in a pipe dropped below the freezing point. General law, as well as particular facts, can be explained by subsumption, the law of conservation of linear momentum can be explained by derivation from Newtons second and third laws of motion. Each of these explanations is a deductive argument: The explanans contains one or more statements of universal laws and, in many cases, statements deceiving initial conditions. This pattern of explanation is known as the deductive-nomological (D-N) model. Any such argument shows that the explanandun had to occur given the explanans.

Many, though not all, adherents of the received view allow for explanation by subsumption under statistical laws. Hempel (1965) offers as an example the case of a man who recovered quickly from a streptococcus infection as a result of treatment with penicillin. Although not all strep infections clar up quickly under this treatment, the probability of recovery in such cases is high, and this is sufficient for legitimate explanation According to Hempel. This example conforms to the inductive-statistical (I-S) model. Such explanations are viewed as arguments, but they are inductive than deductive. In these instances the explanation confers high inductive probability on the explanandum. An explanation of a particular fact satisfying either the ‘D-N’ or ‘I-S’ model is an argument to the effect that the fact in question was to b e expected by virtue of the explanans.

The received view been subjected to strenuous criticism by adherents of the causal/mechanical approach to scientific explanation (Salmon 1990). Many objections to the received view we engendered by he absence of caudal constraints (due largely to worries about Humes critique) on the ‘N-D’ and ‘I-S’ models. Beginning in the late 1950s, Michael Scriven advanced serious counter-examples to Hempels models: He was followed in the 1960s by Wesley Salmon and in the 1970s by Peter Railton. As accorded to the view, one explains phenomena identifying causes (a death is explained resalting from a massive cerebral haemorrhage) or by exposing underlying mechanisms (the behaviour of a gas is explained in terms of the motion of constituent molecules).

A unification approach to explanation carries with the basic idea that we understand our world more adequately to the extent that we can reduce the number of independent assumptions we must introduce to account for what goes on in it. Accordingly, we understand phenomena to the degree that we can fit them into an overall world picture or Weltanschauung. In order to serve in scientific explanation, the world picture must be scientifically well founded.

During the pas half-century much philosophical attention has ben focussed on explanation in science and in history. Considerable controversy has surrounded the question of whether historical explanation must be scientific, or whether history requires explanations of different types. Many diverse views have been articulated: The forgoing brief survey does not exhaust the variety (Salmon, 1990).

In everyday life we encounter many types of explanation, which appear not to raise philosophical difficulties, in addition to those already made of mention. Prior to take-off a flight attendant explains how to use the safety equipment on the aero-plane. In a museum the guide explain the significance of a famous painting. A mathematics teacher explains a geometrical proof to a bewildered student. A newspaper story explains how a prisoner escaped. Additional examples come easily to mind, the main point is to remember the great variety of contexts in which explanations are sought and given into.

Another item of importance to epistemology is the wider held notion that non-demonstrative inferences can be characterized as inference to the best explanation. Given the variety of views on the nature of explanation, this popular slogan can hardly provide a useful philosophical analysis

Early versions of defeasibility theories had difficulty allowing for the existence of evidence that was merely misleading, as in the case where one does know that Tom Grabit stole a book from the library, thanks to having seen him steal it, yet where, unbeknown to oneself, Toms mother out of dementia gas testified that Tom was far away from the library at the time of the theft. Ones justifiably believing that she gave the testimony would destroy ones justification for believing that h3 if added by itself to ones present evidence.

At least some defeasibility theories cannot deal with the knowledge one has while dying that h4: In this life there is no timer at which I believe that ‘d’, where the proposition that d expresses the details regarding some philosophical matter, e.g., the maximum number of blades of grass ever simultaneously growing on the earth. When it just so happens that it is true that ‘d’, defeasibility analyses typically consider the addition to ones dying thoughts of a belief that d in such a way as to improperly rule out actual knowledge that a quite different approach to knowledge, and one able to deal with some Gettier-type cases, involves developing some type of causal theory of Propositional knowledge. The interesting thesis that counts as a causal theory of justification (in the meaning of causal theory: Intended here) is the that of a belief is justified just in case it was produced by a type of process that is globally reliable, that is, its propensity to produce true beliefs-that can be defined (to a god enough approximation) as the proportion of the bailiffs it produces (or would produce where it used as much as opportunity allows) that are true-is sufficiently meaningful-variations of this view have been advanced for both knowledge and justified belief. The first formulation of reliability account of knowing appeared in a note by F.P. Ramsey (1931), who said that a belief was knowledge if it is true, certain can obtain by a reliable process. P. Unger (1968) suggested that ‘S’ knows that ‘p’ just in case it is not at all accidental that ‘S’ is right about its being the case that ‘p’. D.M. Armstrong (1973) said that a non-inferential belief qualified as knowledge if the belief has properties that are nominally sufficient for its truth, i.e., guarantee its truth through and by the laws of nature.

Such theories require that one or another specified relation hold that can be characterized by mention of some aspect of cassation concerning ones belief that ones acceptance of the proposition that its relation to state of affairs, e.g., h causes the belief: h is causally sufficient for the belief h and the belief have a common cause. Such simple versions of a causal theory are able to deal with the original Notgot case, since it involves no such causal relationship, but cannot explain why there is ignorance in the variants where Notgot and Berent Enç (1984) have pointed out that sometimes one knows of P that is ø thanks to recognizing a feature merely corelated with the presence of øness without endorsing a causal theory themselves, there suggest that it would need to be elaborated so as to allow that ones belief that P has ø has been caused by a factor whose correlation with the presence of øness has caused in oneself, e.g., by evolutionary adaption in ones ancestors, the disposition that one manifests in acquiring the belief in response to the correlated factor. Not only does this strain the unity of as causal theory by complicating it, but no causal theory without other shortcomings has been able to cover instances of deductively reasoned knowledge.

Causal theories of Propositional knowledge differ over whether they deviate from the tripartite analysis by dropping the requirements that ones believing (accepting) that h be justified. The same variation occurs regarding reliability theories, which present the Knower as reliable concerning the issue of whether or not h, in the sense that some of ones cognitive or epistemic states, 2, are such that, given further characteristics of oneself-possibly including relations to factors external to one and which one may not be aware-it is nomologically necessary (or at least probable) that h. In some versions, the reliability is required to be global in as far as it must concern a nomologically (probabilistic) relationship) relationship of states of type 2 to the acquisition of true beliefs about a wider range of issues than merely whether or not there is. Also the controversy about how to delineate the limits of what constitutes a type of relevant personal state or characteristic. (For example, in a case where Mr Notgot has not been shamming and one does know thereby that someone in the office owns a Ford, such as a way of forming beliefs about the properties of persons spatially close to one, or instead something narrower, such as a way of forming beliefs about Ford owners in offices partly upon the basis of their relevant testimony?)

One important variety of reliability theory is a conclusive reason account, which includes a requirement that ones reasons for believing that h be such that in ones circumstances, if h* were not to occur then, e.g., one would not have the reasons one does for believing that h, or, e.g., one would not believe that h. Roughly, the latter is demanded by theories that treat a Knower as tracking the truth, theories that include the further demand that is roughly, if it were the case, that h, then one would believe that h. A version of the tracking theory has been defended by Robert Nozick (1981), who adds that if what he calls a method has been used to arrive at the belief that h, then the antecedent clauses of the two conditionals that characterize tracking will need to include the hypothesis that one would employ the very same method.

But unless more conditions are added to Nozicks analysis, it will be too weak to explain why one lacks knowledge in a version of the last variant of the tricky Mr Notgot case described above, where we add the following details: (a) Mr Notgots compulsion is not easily changed, while in the office, Mr Notgot has no other easy trick of the relevant type to play on one, and finally for ones belief that h, not by reasoning through a false belief ut by basing belief that h, upon a true existential generalization of ones evidence.

Some philosophers think that the category of knowing for which is true. Justified believing (accepting) is a requirement constituting only a species of Propositional knowledge, construed as an even broader category. They have proposed various examples of PK that do not satisfy the belief and/ort justification conditions of the tripartite analysis. Such cases are often recognized by analyses of Propositional knowledge in terms of powers, capacities, or abilities. For instance, Alan R. White (1982) treats PK as merely the ability to provide a correct answer to a possible questions, however, White may be equating producing knowledge in the sense of producing the correct answer to a possible question with displaying knowledge in the sense of manifesting knowledge. (White, 1982). The latter can be done even by very young children and some non-human animals independently of their being asked questions, understanding questions, or recognizing answers to questions. Indeed, an example that has been proposed as an instance of knowing that h without believing or accepting that h can be modified so as to illustrate this point. Two examples concerns an imaginary person who has no special training or information about horses or racing, but who in an experiment persistently and correctly picks the winners of upcoming horseraces. If the example is modified so that the hypothetical seer never picks winners but only muses over whether those horses wight win, or only reports those horses winning, this behaviour should be as much of a candidate for the persons manifesting knowledge that the horse in question will win as would be the behaviour of picking it as a winner.

These considerations now placed upon our table, least that we take to consider of their vulnerability, that is in regard to their limitation: Edward Craigs analysis (1990) of the concept of knowing of a persons being a satisfactory informant in relation to an inquirer who wants to find out whether or not h. Craig realizes that counterexamples to his analysis appear to be constituted by Knower who are too recalcitrant to inform the inquirer, or too incapacitate to inform, or too discredited to be worth considering (as with the boy who cried Wolf). Craig admits that this might make preferable some alternative view of knowledge as a different state that helps to explain the presence of the state of being a suitable informant when the latter does obtain. Such the alternate, which offers a recursive definition that concerns ones having the power to proceed in a way representing the state of affairs, causally involved in ones proceeding in this way. When combined with a suitable analysis of representing, this theory of propositional knowledge can be unified with a structurally similar analysis of knowing how to do something.

Knowledge and belief, according to most epistemologists, knowledge entails belief, so that I cannot know that such and such is the case unless I believe that such and such is the case. Others think this entailment thesis can be rendered more accurately if we substitute for belief some closely related attitude. For instance, several philosophers would prefer to say that knowledge entail psychological certainties (Prichard, 1950 and Ayer, 1956) or conviction (Lehrer, 1974) or acceptance (Lehrer, 1989). None the less, there are arguments against all versions of the thesis that knowledge requires having a belief-like attitude toward the known. These arguments are given by philosophers who think that knowledge and belief (or a facsimile) are mutually incompatible (the incomparability thesis), or by ones who say that knowledge does not entail belief, or vice versa, so that each may exist without the other, but the two may also coexist (the separability thesis).

The incompatibility thesis is sometimes traced to Plato (429-347 Bc) in view of his claim that knowledge is infallible while belief or opinion is fallible (Republic 476-9). But this claim would not support the thesis. Belief might be a component of an infallible form of knowledge in spite of the fallibility of belief. Perhaps, knowledge involves some factor that compensates for the fallibility of belief.

A. Duncan-Jones (1939: Also Vendler, 1978) cite linguistic evidence to back up the incompatibility thesis. He notes that people often say I do not believe she is guilty. I know she is and the like, which suggest that belief rule out knowledge. However, as Lehrer (1974) indicates, the above exclamation is only a more emphatic way of saying I do not just believe she is guilty, I know she is where just makes it especially clear that the speaker is signalling that she has something more salient than mere belief, not that she has something inconsistent with belief, namely knowledge. Compare: You do not hurt him, you killed him.

H.A. Prichard (1966) offers a defence of the incompatibility thesis that hinges on the equation of knowledge with certainty (both infallibility and psychological certitude) and the assumption that when we believe in the truth of a claim we are not certain about its truth. Given that belief always involves uncertainty while knowledge never dies, believing something rules out the possibility of knowing it. Unfortunately, however, Prichard gives us no goods reason to grant that states of belief are never ones involving confidence. Conscious beliefs clearly involve some level of confidence, to suggest that we cease to believe things about which we are completely confident is bizarre.

A.D. Woozley (1953) defends a version of the separability thesis. Woozleys version, which deals with psychological certainty rather than belief per se, is that knowledge can exist in the absence of confidence about the item known, although might also be accompanied by confidence as well. Woozley remarks that the test of whether I know something is what I can do, where what I can do may include answering questions. On the basis of this remark he suggests that even when people are unsure of the truth of a claim, they might know that the claim is true. We unhesitatingly attribute knowledge to people who give correct responses on examinations even if those people show no confidence in their answers. Woozley acknowledges, however, that it would be odd for those who lack confidence to claim knowledge. It would be peculiar to say, I am unsure whether my answer is true: Still, I know it is correct But this tension Woozley explains using a distinction between conditions under which we are justified in making a claim (such as a claim to know something), and conditions under which the claim we make is true. While I know such and such might be true even if I am unsure whether such and such holds, nonetheless it would be inappropriate for me to claim that I know that such and such unless I were sure of the truth of my claim.

Colin Radford (1966) extends Woozleys defence of the separability thesis. In Radfords view, not only is knowledge compatible with the lack of certainty, it is also compatible with a complete lack of belief. He argues by example. In one example, Jean has forgotten that he learned some English history years priori and yet he is able to give several correct responses to questions such as When did the Battle of Hastings occur? Since he forgot that he took history, he considers the correct response to be no more than guesses. Thus, when he says that the Battle of Hastings took place in 1066 he would deny having the belief that the Battle of Hastings took place in 1066. A disposition he would deny being responsible (or having the right to be convincing) that 1066 was the correct date. Radford would none the less insist that Jean know when the Battle occurred, since clearly be remembering the correct date. Radford admits that it would be inappropriate for Jean to say that he knew when the Battle of Hastings occurred, but, like Woozley he attributes the impropriety to a fact about when it is and is not appropriate to claim knowledge. When we claim knowledge, we ought, at least to believe that we have the knowledge we claim, or else our behaviour is intentionally misleading.

Those that agree with Radfords defence of the separability thesis will probably think of belief as an inner state that can be detected through introspection. That Jean lacks beliefs about English history is plausible on this Cartesian picture since Jean does not find himself with any beliefs about English history when ne seek them out. One might criticize Radford, however, by rejecting that Cartesian view of belief. One could argue that some beliefs are thoroughly unconscious, for example. Or one could adopt a behaviourist conception of belief, such as Alexander Bains (1859), according to which having beliefs is a matter of the way people are disposed to behave (and has not Radford already adopted a behaviourist conception of knowledge?) Since Jean gives the correct response when queried, a form of verbal behaviour, a behaviourist would be tempted to credit him with the belief that the Battle of Hastings occurred in 1066.

D.M. Armstrong (1873) takes a different tack against Radford. Jean does know that the Battle of Hastings took place in 1066. Armstrong will grant Radfod that point, in fact, Armstrong suggests that Jean believe that 1066 is not the date the Battle of Hastings occurred, for Armstrong equates the belief that such and such is just possible but no more than just possible with the belief that such and such is not the case. However, Armstrong insists, Jean also believes that the Battle did occur in 1066. After all, had Jean been mistaught that the Battle occurred in 1066, and subsequently guessed that it took place in 1066, we would surely describe the situation as one in which Jeans false belief about the Battle became unconscious over time but persisted of a memory trace that was causally responsible for his guess. Out of consistency, we must describe Radfords original case as one that Jeans true belief became unconscious but persisted long enough to cause his guess. Thus, while Jean consciously believes that the Battle did not occur in 1066, unconsciously he does believe it occurred in 1066. So after all, Radford does not have a counterexample to the claim that knowledge entails belief.

Armstrongs response to Radford was to reject Radfords claim that the examinee lacked the relevant belief about English history. Another response is to argue that the examinee lacks the knowledge Radford attributes to him (cf. Sorenson, 1982). If Armstrong is correct in suggesting that Jean believes both that 1066 is and that it is not the date of the Battle of Hastings, one might deny Jean knowledge on the grounds that people who believe the denial of what they believe cannot be said t know the truth of their belief. Another strategy might be to compare the examine case with examples of ignorance given in recent attacks on externalist accounts of knowledge (needless to say. Externalists themselves would tend not to favour this strategy). Consider the following case developed by BonJour (1985): For no apparent reason, Samantha believes that she is clairvoyant. Again, for no apparent reason, she one day comes to believe that the President is in New York City, even though she has every reason to believe that the President is in Washington, DC. In fact, Samantha is a completely reliable clairvoyant, and she has arrived at her belief about the whereabouts of the President thorough the power of her clairvoyance. Yet surely Samanthas belief is completely irrational. She is not justified in thinking what she does. If so, then she does not know where the President is. But Radfords examinee is unconventional. Even if Jean lacks the belief that Radford denies him, Radford does not have an example of knowledge that is unattended with belief. Suppose that Jeans memory had been sufficiently powerful to produce the relevant belief. As Radford says, in having every reason to suppose that his response is mere guesswork, and he has every reason to consider his belief false. His belief would be an irrational one, and hence one about whose truth Jean would be ignorant.

Least has been of mention to an approaching view from which perception basis upon itself as a fundamental philosophical topic both for its central place in ant theory of knowledge, and its central place un any theory of consciousness. Philosophy in this area is constrained by a number of properties that we believe to hold of perception, (1) It gives us knowledge of the world around us, (2) We are conscious of that world by being aware of sensible qualities: Colour, sounds, tastes, smells, felt warmth, and the shapes and positions of objects in the environment. (3) Such consciousness is effected through highly complex information channels, such as the output of the three different types of colour-sensitive cells in the eye, or the channels in the ear for interpreting pulses of air pressure as frequencies of sound. (4) There ensues even more complex neurophysiological coding of that information, and eventually higher-order brain functions bring it about that we interpreted the information so received. (Much of this complexity has been revealed by the difficulties of writing programs enabling computers to recognize quite simple aspects of the visual scene.) The problem is to avoid thinking of here being a central, ghostly, conscious self, fed information in the same way that a screen if fed information by a remote television camera. Once such a model is in place, experience will seem like a veil getting between us and the world, and the direct objects of perception will seem to be private items in an inner theatre or sensorium. The difficulty of avoiding this model is epically cute when we considered the secondary qualities of colour, sound, tactile feelings and taste, which can easily seem to have a purely private existence inside the perceiver, like sensation of pain. Calling such supposed items names like sense-data or percepts exacerbates the tendency, but once the model is in place, the first property, that perception gives us knowledge of the world and its surrounding surfaces, is quickly threatened, for there will now seem little connection between these items in immediate experience and any independent reality. Reactions to this problem include scepticism and idealism.

A more hopeful approach is to claim that the complexities of (3) and (4) explain how we can have direct acquaintance of the world, than suggesting that the acquaintance we do have been at best indirect. It is pointed out that perceptions are not like sensation, precisely because they have a content, or outer-directed nature. To have a perception is to be aware of the world for being such-and-such a way, than to enjoy a mere modification of sensation. But such direct realism has to be sustained in the face of the evident personal (neurophysiological and other) factors determining haw we perceive. One approach is to ask why it is useful to be conscious of what we perceive, when other aspects of our functioning work with information determining responses without any conscious awareness or intervention. A solution to this problem would offer the hope of making consciousness part of the natural world, than a strange optional extra.

Furthering, perceptual knowledge is knowledge acquired by or through the senses and includes most of what we know. We cross intersections when we see the light turn green, head for the kitchen when we smell the roast burning, squeeze the fruit to determine its ripeness, and climb out of bed when we hear the alarm ring. In each case we come to know something-that the light has turned green, that the roast is burning, that the melon is overripe, and that it is time to get up-by some sensory means. Seeing that the light has turned green is learning something-that the light has turned green-by use of the eyes. Feeling that the melon is overripe is coming to know a fact-that the melon is overripe-by ones sense to touch. In each case the resulting knowledge is somehow based on, derived from or grounded in the sort of experience that characterizes the sense modality in question.

Much of our perceptual knowledge is indirect, dependent or derived. By this I mean that the facts we describe ourselves as learning, as coming to know, by perceptual means are pieces of knowledge that depend on our coming to know something else, some other fact, in a more direct way. We see, by the gauge, that we need gas, see, by the newspapers, that our team has lost again, see, by her expression, that she is nervous. This derived or dependent sort of knowledge is particularly prevalent in the cases of vision, but it occurs, to a lesser degree, in every sense modality. We install bells and other noise-makers so that we calm for example, hear (by the bell) that someone is at the door and (by the alarm) that its time to get up. When we obtain knowledge in this way, it is clear that unless one sees-hence, comes to know something about the gauge (that it says) and (hence, know) that one is described as coming to know by perceptual means. If one cannot hear that the bell is ringing, one cannot-in at least in this way-hear that ones visitors have arrived. In such cases one sees (hears, smells, etc.) that ‘a’ is ‘F’, coming to know thereby that ‘a’ is ‘F’, by seeing (hearing, etc.) that some other condition, ‘b’s’ being ‘G’, obtains when this occurs, the knowledge (that a is F) is derived from, or dependent on, the more basic perceptual knowledge that ‘b’ is ‘G’.

And finally, the representational Theory of mind (RTM) (which goes back at least to Aristotle) takes as its starting point commonsense mental states, such as thoughts, beliefs, desires, perceptions and images. Such states are said to have intentionality - they are about or refer to things, and may be evaluated with respect to properties like consistency, truth, appropriateness and accuracy. (For example, the thought that cousins are not related is inconsistent, the belief that Elvis is dead is true, the desire to eat the moon is inappropriate, a visual experience of a ripe strawberry as red is accurate, an image of George W. Bush with deadlocks is inaccurate.)

The Representational Theory of Mind, defines such intentional mental states as relations to mental representations, and explains the intentionality of the former in terms of the semantic properties of the latter. For example, to believe that Elvis is dead is to be appropriately related to a mental representation whose propositional content is that Elvis is dead. (The desire that Elvis be dead, the fear that he is dead, the regret that he is dead, etc., involve different relations to the same mental representation.) To perceive a strawberry is to have a sensory experience of some kind which is appropriately related to (e.g., caused by) the strawberry Representational theory of mind also understands mental processes such as thinking, reasoning and imagining as sequences of intentional mental states. For example, to imagine the moon rising over a mountain is to entertain a series of mental images of the moon (and a mountain). To infer a proposition ‘q’ from the propositions ‘p’ and if ‘p’ then ‘q’ is (among other things) to have a sequence of thoughts of the form ‘p’, if ‘p’ then ‘q,’ ‘q’.

Contemporary philosophers of mind have typically supposed (or at least hoped) that the mind can be naturalized - i.e., that all mental facts have explanations in the terms of natural science. This assumption is shared within cognitive science, which attempts to provide accounts of mental states and processes in terms (ultimately) of features of the brain and central nervous system. In the course of doing so, the various sub-disciplines of cognitive science (including cognitive and computational psychology and cognitive and computational neuroscience) postulate a number of different kinds of structures and processes, many of which are not directly implicated by mental states and processes as commonsensical conceived. There remains, however, a shared commitment to the idea that mental states and processes are to be explained in terms of mental representations.

In philosophy, recent debates about mental representation have centred around the existence of propositional attitudes (beliefs, desires, etc.) and the determination of their contents (how they come to be about what they are about), and the existence of phenomenal properties and their relation to the content of thought and perceptual experience. Within cognitive science itself, the philosophically relevant debates have been focussed on the computational architecture of the brain and central nervous system, and the compatibility of scientific and commonsense accounts of mentality.

Intentional Realists such as Dretske (e.g., 1988) and Fodor (e.g., 1987) note that the generalizations we apply in everyday life in predicting and explaining each others behaviour (often collectively referred to as folk psychology) are both remarkably successful and indispensable. What a person believes, doubts, desires, fears, etc. is a highly reliable indicator of what that person will do; and we have no other way of making sense of each others behaviour than by ascribing such states and applying the relevant generalizations. We are thus committed to the basic truth of commonsense psychology and, hence, to the existence of the states its generalizations refer to. (Some realists, such as Fodor, also hold that commonsense psychology will be vindicated by cognitive science, given that propositional attitudes can be construed as computational relations to mental representations.)

Intentional Eliminativists, such as Churchland, (perhaps) Dennett and (at one time) Stich argue that no such things as propositional attitudes (and their constituent representational states) are implicated by the successful explanation and prediction of our mental lives and behaviour. Churchland denies that the generalizations of commonsense propositional-attitude psychology are true. He (1981) argues that folk psychology is a theory of the mind with a long history of failure and decline, and that it resists incorporation into the framework of modern scientific theories (including cognitive psychology). As such, it is comparable to alchemy and phlogiston theory, and ought to suffer a comparable fate. Commonsense psychology is false, and the states (and representations) it postulates simply don’t exist. (It should be noted that Churchland is not an eliminativist about mental representation tout court.

Dennett (1987) grants that the generalizations of commonsense psychology are true and indispensable, but denies that this is sufficient reason to believe in the entities they appear to refer to. He argues that to give an intentional explanation of a systems behaviour is merely to adopt the intentional stance toward it. If the strategy of assigning contentful states to a system and predicting and explaining its behaviour (on the assumption that it is rational - i.e., that it behaves as it should, given the propositional attitudes it should have in its environment) is successful, then the system is intentional, and the propositional-attitude generalizations we apply to it are true. But there is nothing more to having a propositional attitude than this.

Though he has been taken to be thus claiming that intentional explanations should be construed instrumentally, Dennett (1991) insists that he is a moderate realist about propositional attitudes, since he believes that the patterns in the behaviour and behavioural dispositions of a system on the basis of which we (truly) attribute intentional states to it are objectively real. In the event that there are two or more explanatorily adequate but substantially different systems of intentional ascriptions to an individual, however, Dennett claims there is no fact of the matter about what the system believes (1987, 1991). This does suggest an irrealism at least with respect to the sorts of things Fodor and Dretske take beliefs to be; though it is not the view that there is simply nothing in the world that makes intentional explanations true.

(Davidson 1973, 1974 and Lewis 1974 also defend the view that what it is to have a propositional attitude is just to be interpretable in a particular way. It is, however, not entirely clear whether they intend their views to imply irrealism about propositional attitudes.). Stich (1983) argues that cognitive psychology does not (or, in any case, should not) taxonomize mental states by their semantic properties at all, since attribution of psychological states by content is sensitive to factors that render it problematic in the context of a scientific psychology. Cognitive psychology seeks causal explanations of behaviour and cognition, and the causal powers of a mental state are determined by its intrinsic structural or syntactic properties. The semantic properties of a mental state, however, are determined by its extrinsic properties - e.g., its history, environmental or intra-mental relations. Hence, such properties cannot figure in causal-scientific explanations of behaviour. (Fodor 1994 and Dretske 1988 are realist attempts to come to grips with some of these problems.) Stich proposes a syntactic theory of the mind, on which the semantic properties of mental states play no explanatory role.

It is a traditional assumption among realists about mental representations that representational states come in two basic varieties (Boghossian 1995). There are those, such as thoughts, which are composed of concepts and have no phenomenal (what-its-like) features (qualia), and those, such as sensory experiences, which have phenomenal features but no conceptual constituents. (Non-conceptual content is usually defined as a kind of content that states of a creature lacking concepts might nonetheless enjoy. On this taxonomy, mental states can represent either in a way analogous to expressions of natural languages or in a way analogous to drawings, paintings, maps or photographs. (Perceptual states such as seeing that something is blue, are sometimes thought of as hybrid states, consisting of, for example, a Non-conceptual sensory experience and a thought, or some more integrated compound of sensory and conceptual components.)

Some historical discussions of the representational properties of mind (e.g., Aristotle 1984, Locke 1689/1975, Hume 1739/1978) seem to assume that Non-conceptual representations - percepts (impressions), images (ideas) and the like - are the only kinds of mental representations, and that the mind represents the world in virtue of being in states that resemble things in it. On such a view, all representational states have their content in virtue of their phenomenal features. Powerful arguments, however, focussing on the lack of generality (Berkeley 1975), ambiguity (Wittgenstein 1953) and non-compositionality (Fodor 1981) of sensory and imagistic representations, as well as their unsuitability to function as logical (Frége 1918/1997, Geach 1957) or mathematical (Frége 1884/1953) concepts, and the symmetry of resemblance (Goodman 1976), convinced philosophers that no theory of mind can get by with only Non-conceptual representations construed in this way.

Contemporary disagreement over Non-conceptual representation concerns the existence and nature of phenomenal properties and the role they play in determining the content of sensory experience. Dennett (1988), for example, denies that there are such things as qualia at all; while Brandom (2002), McDowell (1994), Rey (1991) and Sellars (1956) deny that they are needed to explain the content of sensory experience. Among those who accept that experiences have phenomenal content, some (Dretske, Lycan, Tye) argue that it is reducible to a kind of intentional content, while others (Block, Loar, Peacocke) argue that it is irreducible.

There has also been dissent from the traditional claim that conceptual representations (thoughts, beliefs) lack phenomenology. Chalmers (1996), Flanagan (1992), Goldman (1993), Horgan and Tiensen (2003), Jackendoff (1987), Levine (1993, 1995, 2001), McGinn (1991), Pitt (2004), Searle (1992), Siewert (1998) and Strawson (1994), claim that purely symbolic (conscious) representational states themselves have a (perhaps proprietary) phenomenology. If this claim is correct, the question of what role phenomenology plays in the determination of content reprises for conceptual representation; and the eliminativist ambitions of Sellars, Brandom, Rey, would meet a new obstacle. (It would also raise prima face problems for reductionist representations.

The representationalist thesis is often formulated as the claim that phenomenal properties are representational or intentional. However, this formulation is ambiguous between a reductive and a non-deductive claim (though the term representationalism is most often used for the reductive claim). On one hand, it could mean that the phenomenal content of an experience is a kind of intentional content (the properties it represents). On the other, it could mean that the (irreducible) phenomenal properties of an experience determine an intentional content. Representationalists such as Dretske, Lycan and Tye would assent to the former claim, whereas phenomenalists such as Block, Chalmers, Loar and Peacocke would assent to the latter. (Among phenomenalists, there is further disagreement about whether qualia are intrinsically representational (Loar) or not (Block, Peacocke).

Most (reductive) representationalists are motivated by the conviction that one or another naturalistic explanation of intentionality is, in broad outline, correct, and by the desire to complete the naturalization of the mental by applying such theories to the problem of phenomenality. (Needless to say, most phenomenalists (Chalmers is the major exception) are just as eager to naturalize the phenomenal - though not in the same way.)

The main argument for representationalism appeals to the transparency of experience (Tye 2000). The properties that characterize what its like to have a perceptual experience are presented in experience as properties of objects perceived: in attending to an experience, one seems to see through it to the objects and properties it is experiences of. They are not presented as properties of the experience itself. If nonetheless they were properties of the experience, perception would be massively deceptive. But perception is not massively deceptive. According to the representationalist, the phenomenal character of an experience is due to its representing objective, non-experiential properties. (In veridical perception, these properties are locally instantiated; in illusion and hallucination, they are not.) On this view, introspection is indirect perception: one comes to know what phenomenal features ones experience has by coming to know what objective features it represents.

In order to account for the intuitive differences between conceptual and sensory representations, representationalists appeal to their structural or functional differences. Dretske (1995), for example, distinguishes experiences and thoughts on the basis of the origin and nature of their functions: an experience of a property P is a state of a system whose evolved function is to indicate the presence of P in the environment; a thought representing the property P, on the other hand, is a state of a system whose assigned (learned) function is to calibrate the output of the experiential system. Rey (1991) takes both thoughts and experiences to be relations to sentences in the language of thought, and distinguishes them on the basis of (the functional roles of) such sentences constituent predicates. Lycan (1987, 1996) distinguishes them in terms of their functional-computational profiles. Tye (2000) distinguishes them in terms of their functional roles and the intrinsic structure of their vehicles: thoughts are representations in a language-like medium, whereas experiences are image-like representations consisting of symbol-filled arrays. (the account of mental images in Tye 1991.)

Phenomenalists tend to make use of the same sorts of features (function, intrinsic structure) in explaining some of the intuitive differences between thoughts and experiences; but they do not suppose that such features exhaust the differences between phenomenal and non-phenomenal representations. For the phenomenalism, it is the phenomenal properties of experiences - qualia themselves - that constitute the fundamental difference between experience and thought. Peacocke (1992), for example, develops the notion of a perceptual scenario (an assignment of phenomenal properties to coordinates of a three-dimensional egocentric space), whose content is correct (a semantic property) if in the corresponding scene (the portion of the external world represented by the scenario) properties are distributed as their phenomenal analogues are in the scenario.

Another sort of representation championed by phenomenalists, e.g., Block, Chalmers (2003) and Loar (1996) is the phenomenal concept - a conceptual/phenomenal hybrid consisting of a phenomenological sample (an image or an occurrent sensation) integrated with (or functioning as) a conceptual component. Phenomenal concepts are postulated to account for the apparent fact (among others) that, as McGinn (1991) puts it, you cannot form [introspective] concepts of conscious properties unless you yourself instantiate those properties. One cannot have a phenomenal concept of a phenomenal property ‘P’, and, hence, phenomenal beliefs about ‘P’, without having experience of ‘P’, because P itself is (in some way) constitutive of the concept of ‘P’. (Jackson 1982, 1986 and Nagel 1974.)

Though imagery has played an important role in the history of philosophy of mind, the important contemporary literature on it is primarily psychological. In a series of psychological experiments done in the 1970s (summarized in Kosslyn 1980 and Shepard and Cooper 1982), subjects response time in tasks involving mental manipulation and examination of presented figures was found to vary in proportion to the spatial properties (size, orientation, etc.) of the figures presented. The question of how these experimental results are to be explained has kindled a lively debate on the nature of imagery and imagination.

Kosslyn (1980) claims that the results suggest that the tasks were accomplished via the examination and manipulation of mental representations that themselves have spatial properties - i.e., pictorial representations, or images. Others, principally Pylyshyn (1979, 1981, 2003), argue that the empirical facts can be explained in terms exclusively of discursive, or propositional representations and cognitive processes defined over them. (Pylyshyn takes such representations to be sentences in a language of thought.)

The idea that pictorial representations are literally pictures in the head is not taken seriously by proponents of the pictorial view of imagery The claim is, rather, that mental images represent in a way that is relevantly like the way pictures represent. (Attention has been focussed on visual imagery - hence the designation pictorial; though of course there may imagery in other modalities - auditory, olfactory, etc. - as well.)

The distinction between pictorial and discursive representation can be characterized in terms of the distinction between analog and digital representation (Goodman 1976). This distinction has itself been variously understood (Fodor & Pylyshyn 1981, Goodman 1976, Haugeland 1981, Lewis 1971, McGinn 1989), though a widely accepted construal is that analog representation is continuous (i.e., in virtue of continuously variable properties of the representation), while digital representation is discrete (i.e., in virtue of properties a representation either has or doesnt have) (Dretske 1981). (An analog/digital distinction may also be made with respect to cognitive processes. (Block 1983.)) On this understanding of the analog/digital distinction, imagistic representations, which represent in virtue of properties that may vary continuously (such as being more or less bright, loud, vivid, etc.), would be analog, while conceptual representations, whose properties do not vary continuously (a thought cannot be more or less about Elvis: either it is or it is not) would be digital.

It might be supposed that the pictorial/discursive distinction is best made in terms of the phenomenal and nonphenomenal distinction, but it is not obvious that this is the case. For one thing, there may be nonphenomenal properties of representations that vary continuously. Moreover, there are ways of understanding pictorial representation that presuppose neither phenomenality nor analogicity. According to Kosslyn (1980, 1982, 1983), a mental representation is quasi-pictorial when every part of the representation corresponds to a part of the object represented, and relative distances between parts of the object represented are preserved among the parts of the representation. But distances between parts of a representation can be defined functionally rather than spatially - for example, in terms of the number of discrete computational steps required to combine stored information about them. (Rey 1981.)

Tye (1991) proposes a view of images on which they are hybrid representations, consisting both of pictorial and discursive elements. On Tyes account, images are (labelled) interpreted symbol-filled arrays. The symbols represent discursively, while their arrangement in arrays has representational significance (the location of each cell in the array represents a specific viewer-centred 2-D location on the surface of the imagined object)

The contents of mental representations are typically taken to be abstract objects (properties, relations, propositions, sets, etc.). A pressing question, especially for the naturalist, is how mental representations come to have their contents. Here the issue is not how to naturalize content (abstract objects cant be naturalized), but, rather, how to provide a naturalistic account of the content-determining relations between mental representations and the abstract objects they express. There are two basic types of contemporary naturalistic theories of content-determination, causal-informational and functional.

Causal-informational theories (Dretske 1981, 1988, 1995) hold that the content of a mental representation is grounded in the information it carries about what does (Devitt 1996) or would (Fodor 1987, 1990) cause it to occur. There is, however, widespread agreement that causal-informational relations are not sufficient to determine the content of mental representations. Such relations are common, but representation is not. Tree trunks, smoke, thermostats and ringing telephones carry information about what they are causally related to, but they do not represent (in the relevant sense) what they carry information about. Further, a representation can be caused by something it does not represent, and can represent something that has not caused it.

The main attempts to specify what makes a causal-informational state a mental representation are Asymmetric Dependency Theories (e.g., Fodor 1987, 1990, 1994) and Teleological Theories (Fodor 1990, Millikan 1984, Papineau 1987, Dretske 1988, 1995). The Asymmetric Dependency Theory distinguishes merely informational relations from representational relations on the basis of their higher-order relations to each other: informational relations depend upon representational relations, but not vice-versa. For example, if tokens of a mental state type are reliably caused by horses, cows-on-dark-nights, zebras-in-the-mist and Great Danes, then they carry information about horses, etc. If, however, such tokens are caused by cows-on-dark-nights, etc. because they were caused by horses, but not vice versa, then they represent horses.

According to Teleological Theories, representational relations are those a representation-producing mechanism has the selected (by evolution or learning) function of establishing. For example, zebra-caused horse-representations do not mean zebra, because the mechanism by which such tokens are produced has the selected function of indicating horses, not zebras. The horse-representation-producing mechanism that responds to zebras is malfunctioning.

Functional theories (Block 1986, Harman 1973), hold that the content of a mental representation is grounded in its (causal computational, inferential) relations to other mental representations. They differ on whether relata should include all other mental representations or only some of them, and on whether to include external states of affairs. The view that the content of a mental representation is determined by its inferential/computational relations with all other representations is holism; the view it is determined by relations to only some other mental states is localism (or molecularism). (The view that the content of a mental state depends on none of its relations to other mental states is atomism.) Functional theories that recognize no content-determining external relata have been called solipsistic (Harman 1987). Some theorists posit distinct roles for internal and external connections, the former determining semantic properties analogous to sense, the latter determining semantic properties analogous to reference (McGinn 1982, Sterelny 1989)

(Reductive) representationalists (Dretske, Lycan, Tye) usually take one or another of these theories to provide an explanation of the (Non-conceptual) content of experiential states. They thus tend to be Externalists about phenomenological as well as conceptual content. Phenomenalists and non-deductive representationalists (Block, Chalmers, Loar, Peacocke, Siewert), on the other hand, take it that the representational content of such states is (at least in part) determined by their intrinsic phenomenal properties. Further, those who advocate a phenomenology-based approach to conceptual content (Horgan and Tiensen, Loar, Pitt, Searle, Siewert) also seem to be committed to internalist individuation of the content (if not the reference) of such states.

Generally, those who, like informational theorists, think relations to ones (natural or social) environment are (at least partially) determinative of the content of mental representations are Externalists (e.g., Burge 1979, 1986, McGinn 1977, Putnam 1975), whereas those who, like some proponents of functional theories, think representational content is determined by an individuals intrinsic properties alone, are internalists (or individualists; cf. Putnam 1975, Fodor 1981)

This issue is widely taken to be of central importance, since psychological explanation, whether commonsense or scientific, is supposed to be both causal and content-based. (Beliefs and desires cause the behaviours they do because they have the contents they do. For example, the desire that one have a beer and the beliefs that there is beer in the refrigerator and that the refrigerator is in the kitchen may explain ones getting up and going to the kitchen.) If, however, a mental representations having a particular content is due to factors extrinsic to it, it is unclear how its having that content could determine its causal powers, which, arguably, must be intrinsic. Some who accept the standard arguments for externalism have argued that internal factors determine a component of the content of a mental representation. They say that mental representations have both narrow content (determined by intrinsic factors) and wide or broad content (determined by narrow content plus extrinsic factors). (This distinction may be applied to the sub-personal representations of cognitive science as well as to those of commonsense psychology.

Narrow content has been variously construed. Putnam (1975), Fodor (1982)), and Block (1986), for example, seem to understand it as something like dedicto content (i.e., Frégean sense, or perhaps character, à la Kaplan 1989). On this construal, narrow content is context-independent and directly expressible. Fodor (1987) and Block (1986), however, have also characterized narrow content as radically inexpressible. On this construal, narrow content is a kind of proto-content, or content-determinant, and can be specified only indirectly, via specifications of context/wide-content pairings. On both construal, narrow contents are characterized as functions from context to (wide) content. The narrow content of a representation is determined by properties intrinsic to it or its possessor such as its syntactic structure or its intra-mental computational or inferential role (or its phenomenology).

Burge (1986) has argued that causation-based worries about externalist individuation of psychological content, and the introduction of the narrow notion, are misguided. Fodor (1994, 1998) has more recently urged that a scientific psychology might not need narrow content in order to supply naturalistic (causal) explanations of human cognition and action, since the sorts of cases they were introduced to handle, viz., Twin-Earth cases and Frigg cases, are either nomologically impossible or dismissible as exceptions to non-strict psychological laws.

The leading contemporary version of the Representational Theory of Mind, the Computational Theory of Mind (CTM), claims that the brain is a kind of computer and that mental processes are computations. According to the computational theory of mind, cognitive states are constituted by computational relations to mental representations of various kinds, and cognitive processes are sequences of such states. The computational theory of mind and the representational theory of mind, may by attempting to explain all psychological states and processes in terms of mental representation. In the course of constructing detailed empirical theories of human and animal cognition and developing models of cognitive processes implementable in artificial information processing systems, cognitive scientists have proposed a variety of types of mental representations. While some of these may be suited to be mental relata of commonsense psychological states, some - so-called subpersonal or sub-doxastic representations - are not. Though many philosophers believe that computational theory of mind can provide the best scientific explanations of cognition and behaviour, there is disagreement over whether such explanations will vindicate the commonsense psychological explanations of prescientific representational theory of mind.

According to Stichs (1983) Syntactic Theory of Mind, for example, computational theories of psychological states should concern themselves only with the formal properties of the objects those states are relations to. Commitment to the explanatory relevance of content, however, is for most cognitive scientists fundamental (Fodor 1981, Pylyshyn 1984, Von Eckardt 1993). That mental processes are computations, which computations are rule-governed sequences of semantically evaluable objects, and that the rules apply to the symbols in virtue of their content, are central tenets of mainstream cognitive science.

Explanations in cognitive science appeal to a many different kinds of mental representation, including, for example, the mental models of Johnson-Laird 1983, the retinal arrays, primal sketches and 2½ -D sketches of Marr 1982, the frames of Minsky 1974, the sub-symbolic structures of Smolensky 1989, the quasi-pictures of Kosslyn 1980, and the interpreted symbol-filled arrays of Tye 1991 - in addition to representations that may be appropriate to the explanation of commonsense psychological states. Computational explanations have been offered of, among other mental phenomena, belief (Fodor 1975, Field 1978), visual perception (Marr 1982, Osherson, 1990), rationality (Newell and Simon 1972, Fodor 1975, Johnson-Laird and Wason 1977), language learning and (Chomsky 1965, Pinker 1989), and musical comprehension (Lerdahl and Jackendoff 1983).

A fundamental disagreement among proponents of computational theory of mind concerns the realization of personal-level representations (e.g., thoughts) and processes (e.g., inferences) in the brain. The central debate here is between proponents of Classical Architectures and proponents of Conceptionist Architectures.

The classicists (e.g., Turing 1950, Fodor 1975, Fodor and Pylyshyn 1988, Marr 1982, Newell and Simon 1976) hold that mental representations are symbolic structures, which typically have semantically evaluable constituents, and that mental processes are rule-governed manipulations of them that are sensitive to their constituent structure. The connectionists (e.g., McCulloch & Pitts 1943, Rumelhart 1989, Rumelhart and McClelland 1986, Smolensky 1988) hold that mental representations are realized by patterns of activation in a network of simple processors (nodes) and that mental processes consist of the spreading activation of such patterns. The nodes themselves are, typically, not taken to be semantically evaluable; nor do the patterns have semantically evaluable constituents. (Though there are versions of Connectionism - localist versions - on which individual nodes are taken to have semantic properties (e.g., Ballard 1986, Ballard & Hayes 1984).) It is arguable, however, that localist theories are neither definitive nor representative of the Conceptionist program (Smolensky 1988, 1991, Chalmers 1993).

Classicists are motivated (in part) by properties thought seems to share with language. Fodors Language of Thought Hypothesis (LOTH) (Fodor 1975, 1987), according to which the system of mental symbols constituting the neural basis of thought is structured like a language, provides a well-worked-out version of the classical approach as applied to commonsense psychology. According to the language of thought hypothesis, the potential infinity of complex representational mental states is generated from a finite stock of primitive representational states, in accordance with recursive formation rules. This combinatorial structure accounts for the properties of productivity and systematicity of the system of mental representations. As in the case of symbolic languages, including natural languages (though Fodor does not suppose either that the language of thought hypothesis explains only linguistic capacities or that only verbal creatures have this sort of cognitive architecture), these properties of thought are explained by appeal to the content of the representational units and their combinability into contentful complexes. That is, the semantics of both language and thought is compositional: the content of a complex representation is determined by the contents of its constituents and their structural configuration.

Connectionists are motivated mainly by a consideration of the architecture of the brain, which apparently consists of layered networks of interconnected neurons. They argue that this sort of architecture is unsuited to carrying out classical serial computations. For one thing, processing in the brain is typically massively parallel. In addition, the elements whose manipulation drives computation in Conceptionist networks (principally, the connections between nodes) are neither semantically compositional nor semantically evaluable, as they are on the classical approach. This contrast with classical computationalism is often characterized by saying that representation is, with respect to computation, distributed as opposed to local: representation is local if it is computationally basic; and distributed if it is not. (Another way of putting this is to say that for classicists mental representations are computationally atomic, whereas for connectionists they are not.)

Moreover, connectionists argue that information processing as it occurs in Conceptionist networks more closely resembles some features of actual human cognitive functioning. For example, whereas on the classical view learning involves something like hypothesis formation and testing (Fodor 1981), on the Conceptionist model it is a matter of evolving distribution of weight (strength) on the connections between nodes, and typically does not involve the formulation of hypotheses regarding the identity conditions for the objects of knowledge. The Conceptionist network is trained up by repeated exposure to the objects it is to learn to distinguish; and, though networks typically require many more exposures to the objects than do humans, this seems to model at least one feature of this type of human learning quite well.

Further, degradation in the performance of such networks in response to damage is gradual, not sudden as in the case of a classical information processor, and hence more accurately models the loss of human cognitive function as it typically occurs in response to brain damage. It is also sometimes claimed that Conceptionist systems show the kind of flexibility in response to novel situations typical of human cognition - situations in which classical systems are relatively brittle or fragile.

Some philosophers have maintained that Connectionism entails that there are no propositional attitudes. Ramsey, Stich and Garon (1990) have argued that if Conceptionist models of cognition are basically correct, then there are no discrete representational states as conceived in ordinary commonsense psychology and classical cognitive science. Others, however (e.g., Smolensky 1989), hold that certain types of higher-level patterns of activity in a neural network may be roughly identified with the representational states of commonsense psychology. Still others (e.g., Fodor & Pylyshyn 1988, Heil 1991, Horgan and Tienson 1996) argue that language-of-thought style representation is both necessary in general and realizable within Conceptionist architectures. (MacDonald & MacDonald 1995 collects the central contemporary papers in the classicist/Conceptionist debate, and provides useful introductory material as well.

Whereas Stich (1983) accepts that mental processes are computational, but denies that computations are sequences of mental representations, others accept the notion of mental representation, but deny that computational theory of mind provides the correct account of mental states and processes.

Van Gelder (1995) denies that psychological processes are computational. He argues that cognitive systems are dynamic, and that cognitive states are not relations to mental symbols, but quantifiable states of a complex system consisting of (in the case of human beings) a nervous system, a body and the environment in which they are embedded. Cognitive processes are not rule-governed sequences of discrete symbolic states, but continuous, evolving total states of dynamic systems determined by continuous, simultaneous and mutually determining states of the systems components. Representation in a dynamic system is essentially information-theoretic, though the bearers of information are not symbols, but state variables or parameters.

Horst (1996), on the other hand, argues that though computational models may be useful in scientific psychology, they are of no help in achieving a philosophical understanding of the intentionality of commonsense mental states. computational theory of mind attempts to reduce the intentionality of such states to the intentionality of the mental symbols they are relations to. But, Horst claims, the relevant notion of symbolic content is essentially bound up with the notions of convention and intention. So the computational theory of mind involves itself in a vicious circularity: the very properties that are supposed to be reduced are (tacitly) appealed to in the reduction.

To say that a mental object has semantic properties is, paradigmatically, to say that it may be about, or be true or false of, an object or objects, or that it may be true or false simpliciter. Suppose I think that ocelots take snuff. I am thinking about ocelots, and if what I think of them (that they take snuff) is true of them, then my thought is true. According to representational theory of mind such states are to be explained as relations between agents and mental representations. To think that ocelots take snuff is to token in some way a mental representation whose content is that ocelots take snuff. On this view, the semantic properties of mental states are the semantic properties of the representations they are relations to.

Linguistic acts seem to share such properties with mental states. Suppose I say that ocelots take snuff. I am talking about ocelots, and if what I say of them (that they take snuff) is true of them, then my utterance is true. Now, to say that ocelots take snuff is (in part) to utter a sentence that means that ocelots take snuff. Many philosophers have thought that the semantic properties of linguistic expressions are inherited from the intentional mental states they are conventionally used to express (Grice 1957, Fodor 1978, Schiffer, 1972/1988, Searle 1983). On this view, the semantic properties of linguistic expressions are the semantic properties of the representations that are the mental relata of the states they are conventionally used to express.

It is also widely held that in addition to having such properties as reference, truth-conditions and truth - so-called extensional properties - expressions of natural languages also have intensional properties, in virtue of expressing properties or propositions - i.e., in virtue of having meanings or senses, where two expressions may have the same reference, truth-conditions or truth value, yet express different properties or propositions (Frigg 1892/1997). If the semantic properties of natural-language expressions are inherited from the thoughts and concepts they express (or vice versa, or both), then an analogous distinction may be appropriate for mental representations.

Søren Aabye Kierkegaard (1813-1855), a Danish religious philosopher, whose concern with individual existence, choice, and commitment profoundly influenced modern theology and philosophy, especially existentialism.

Søren Kierkegaard wrote of the paradoxes of Christianity and the faith required to reconcile them. In his book Fear and Trembling, Kierkegaard discusses Genesis 22, in which God commands Abraham to kill his only son, Isaac. Although God made an unreasonable and immoral demand, Abraham obeyed without trying to understand or justify it. Kierkegaard regards this leap of faith as the essence of Christianity.

Kierkegaard was born in Copenhagen on May 15, 1813. His father was a wealthy merchant and strict Lutheran, whose gloomy, guilt-ridden piety and vivid imagination strongly influenced Kierkegaard. Kierkegaard studied theology and philosophy at the University of Copenhagen, where he encountered Hegelian philosophy and reacted strongly against it. While at the university, he ceased to practice Lutheranism and for a time led an extravagant social life, becoming a familiar figure in the theatrical and lodges, for what seemed as the sociological hosting attributions for beaming intellectuals that resided in Copenhagen. After his father’s death in 1838, however, he decided to resume his theological studies. In 1840 he became engaged to the 17-year-old Regine Olson, but almost immediately he began to suspect that marriage was incompatible with his own brooding, complicated nature and his growing sense of a philosophical vocation. He abruptly broke off the engagement in 1841, but the episode took on great significance for him, and he repeatedly alluded to it in his books. At the same time, he realized that he did not want to become a Lutheran pastor. An inheritance from his father allowed him to devote himself entirely to writing, and in the remaining 14 years of his life he produced more than 20 books.

Kierkegaards work is deliberately unsystematic and consists of essays, aphorisms, parables, fictional letters and diaries, and other literary forms. Many of his works were originally published under pseudonyms. He applied the term existential to his philosophy because he regarded philosophy as the expression of an intensely examined individual life, not as the construction of a monolithic system in the manner of the 19th-century German philosopher Georg Wilhelm Friedrich Hegel, whose work he attacked in Concluding Unscientific Postscript (1846; translated 1941). Hegel claimed to have achieved a complete rational understanding of human life and history; Kierkegaard, on the other hand, stressed the ambiguity and paradoxical nature of the human situation. The fundamental problems of life, he contended, defy rational, objective explanation; the highest truth is subjective.

Kierkegaard maintained that systematic philosophy not only imposed a false perspective on human existence but that it also, by explaining life in terms of logical necessity, becomes a means of avoiding choice and responsibility. Individuals, he believed, create their own natures through their choices, which must be made in the absence of universal, objective standards. The validity of a choice can only be determined subjectively.

In his first major work, Either/Or (two volumes, 1843; translated 1944), Kierkegaard described two spheres, or stages of existence, that the individual may choose: the aesthetic and the ethical. The character that gives to the study of conceptual representations involves the side of practical reasoning, of good, right, duty, obligation, virtue, freedom, rationality, and choice. Also, and without exception the affiliated contributors to the second-order study of objectivity, subjectivity, relativism, or scepticism, in that it may administer to claims made in these terms. For the kinds of problems encountered, that of which the subject that applies ethics to actual practical problems, is such as those of abortion, euthanasia, treatment of animals, or other generally shared in or participated problems. That the claims of ethics are objectively true, they are not relative to a subject or a culture, nor purely subjective in their nature, in opposition to error theories, scepticism and relativism. The central problem is finding the source of the required objectivity. Intricately accorded by some sorted existence or a place of ethical properties and ethical thought in the matter-of-course, free from pretension or calculably opened conditions that display of an unclothed world. In the form as aforementioned, and supposedly refuted by the British philosopher George Edward Moore (1873-1958), this is the view that the meaning of an ethical predicate (‘ . . . is good) is identical with that of a predicate displaying the features in virtue of which the object is good, e.g., . . . ‘is such as to create happiness’, if one operates a utilitarian standard. Moore attacks this with the open question argument. Other positions calling them naturalism may abandon the claim about identity of meaning, but still hold that ethical properties which are identical with natural properties, rather as we hold that water is such, that even if the two terms mean something different, most widely, naturalism includes any belief that the nature of ethical thinking is exhaustively understood in terms of natural propensities of human beings, without mysterious intuitions, or operations of conscience, or divine help.

Although the morality of people and their ethics amount to the same thing, there is a usage that restricts morality to systems such as that of Kant, based on notions such as duty, obligation, and principles of conduct, reserving ethics for the more Aristotelian approach to practical reasoning, as it is based on the notion of a virtue and generally avoiding the separation of ‘moral’ considerations from other practical considerations. The scholarly issues are complex, with some writers seeing Kant as more Aristotelian and Aristotle as more involved with a separate sphere of responsibility and duty, than the simple contrast suggests.

Its consequence or prominence is eminently exceeded by something that aesthetic ways of life, are the pursuit factors of one’s own pleasure as an end in itself, in ethics the view that such a pursuit is the proper aim of all action. The psychological pursuit of one’s own ‘pleasure’ as an end in itself, is rooted in the ethical view that such a pursuit is the proper alliance intended of all action. Since there are different conceptions of pleasure, there is correspondingly different varieties of hedonism. Unless one’s own pleasure can somehow be identified with that of others. Hedonism stands opposed to the disinterested concern for others commonly thought to be essential elements of morality, although there are various ways of tying to align the pursuit of selfish pleasures. In that with some aligned degree of concern for others, psychological hedonism, is the view that either contingently, because of our human nature, or as a matter of conceptual necessity, as people only pursue their own pleasures. It is not true, on either construction, although the morality of people and their ethics amount to the same thing, there is a usage that restricts morality to systems such as that of Immanuel Kant (1724-1804), the German philosopher and founder of critical philosophy, that based on notions such as duty, obligation, and principles of conduct, wherefore, reserving ethics for the more Aristotelean approach to practical reasoning, and, again, is based on the notion of a virtue and generally to avoid such as the separation of moral considerations from those that are otherwise practically in the same. In various ways that which is the view that either contingently, because of our human nature, or as a matter of conceptual necessity, are those of the people that only pursue their own pleasures. It is not true, on either construction, however, if it is refined hedonism, hence consisting of a search for pleasure and a cultivation of a mood. The aesthetic individual constantly seeks variety and novelty in an effort to stave off boredom but eventually must confront boredom and despair. The ethical way of life involves an intense, passionate commitment to duty, to unconditional social and religious obligations. His later influence expanded in the 20th century, in particular amongst thinkers concerned with problems of religious and ethical choice, and especially among existentialists concerned with the same problems. His works include Enten-eller, 1843, translated as, Either/Or: A Fragment of Life, 1944. Afsluttende Uvidenskabelig Efterskrift (1846, translated as, Concluding Unscientific Postscript, 1941), and Sygdomen Til Deden (1849, translated as The Sickness unto Death, 1941), the compositions, such as Stages on Lifes Way (1845; translated 1940), Kierkegaard’s understanding of his submission to duty as the loss of individual responsibility, whereby he proposed of the cultural religion, under which one submits to the will of God, but in doing so he finds something that is authentic and generatively forwarded to freedom. Fragments from these sentences are accorded by the literature as they are marked and noted as, In Fear and Trembling (1846; translated 1941). Kierkegaard focused on Gods command that Abraham sacrifice his son Isaac (Genesis 22: 1-19), of which is the greatest and ultimate of sacrifices that violates Abrahams ethical convictions. Abraham proves his faith by resolutely setting out to obey Gods command, even though he cannot understand it. This suspension of the ethical, as Kierkegaard called it, allows Abraham to achieve an authentic commitment to God. To avoid ultimate despair, the individual must make a similar leap of faith into a religious life, which is inherently paradoxical, mysterious, and full of risk. One is called to it by the feeling of dread (The Concept of Dread, 1844; translated 1944), which is explicitly implicate the ultimate fear of nothingness.

Toward the end of his life Kierkegaard was involved in bitter controversies, especially with the established Danish Lutheran church, which he regarded as worldly and corrupt. His later works, such as The Sickness Unto Death (1849; translated 1941), reflect an increasingly somber view of Christianity, emphasizing suffering as the essence of authentic faith. He also intensified his attack on modern European society, which he denounced in The Present Age (1846; translated 1940) its lack of warming passion and its quantitative sense of value. The stress of his prolific writings and of the controversies under which he engaged gradually undermined his health, and in October 1855 he fainted in defeat as he was to vanquish into the chambering avenues in that he died in Copenhagen on November 11, 1855.

Kierkegaards influence was at first confined to Scandinavia and to German-speaking Europe, where his work had a strong impact on Protestant Theology and on such writers as the 20th-century Austrian novelist Franz Kafka. As existentialism emerged as a general European movement after World War I, Kierkegaards work was widely translated, and he was recognized as one of the seminal figures of modern culture.

Since scientists, during the nineteenth century were engrossed with uncovering the workings of external reality and seemingly knew of themselves that these virtually overflowing burdens of nothing, in that were about the physical substrates of human consciousness, the business of examining the distributive contribution in dynamic functionality and structural foundation of mind became the province of social scientists and humanists. Adolphe Quételet proposed a social physics that could serve as the basis for a new discipline called sociology, and his contemporary Auguste Comte concluded that a true scientific understanding of the social reality was quite inevitable. Mind, in the view of these figures, was a separate and distinct mechanism subject to the lawful workings of a mechanical social reality.

More formal European philosophers, such as Immanuel Kant, sought to reconcile representations of external reality in mind with the motions of matter-based on the dictates of pure reason. This impulse was also apparent in the utilitarian ethics of Jerry Bentham and John Stuart Mill, in the historical materialism of Karl Marx and Friedrich Engels, and in the pragmatism of Charles Smith, William James and John Dewey. These thinkers were painfully aware, however, of the inability of reason to posit a self-consistent basis for bridging the gap between mind and matter, and each remains obliged to conclude that the realm of the mental exists only in the subjective reality of the individual.

The fatal flaw of pure reason is, of course, the absence of emotion, and purely explanations of the division between subjective reality and external reality, of which had limited appeal outside the community of intellectuals. The figure most responsible for infusing our understanding of the Cartesian dualism with contextual representation of our understanding with emotional content was the death of God theologian Friedrich Nietzsche 1844-1900. After declaring that God and divine will, did not exist, Nietzsche reified the existence of consciousness in the domain of subjectivity as the ground for individual will and summarily reducing all previous philosophical attempts to articulate the will to truth. The dilemma, forth in, had seemed to mean, by the validation, . . . as accredited for doing of science, in that the claim that Nietzsche earlier version to the will to truth, disguises the fact that all alleged truths were arbitrarily created in the subjective reality of the individual and are expressed or manifesting the individualism of will.

In Nietzsches’ view, the separation between mind and matter is more absolute and total than previously been imagined. Based on the assumption that there is no real necessity to account for its correspondence between linguistic constructions of reality or the position as held within human subjectivity and external reality. He deduced that we are all locked in a prison house of language. And the prison, as he concluded it, was also a space where the philosopher can examine the innermost desires of his nature and articulate a new message of individual existence founded on will.

Those who fail to enact their existence in this space, Nietzsche says, are enticed into sacrificing their individuality on the nonexistent altars of religious beliefs and democratic or socialists’ ideals and become, therefore, members of the anonymous and docile crowd. Nietzsche also invalidated the knowledge claims of science in the examination of human subjectivity. Science, he said. Is not exclusive to natural phenomenons and favors reductionistic examination of phenomena at the expense of mind? It also seeks to reduce the separateness and uniqueness of mind with mechanistic descriptions that disallow and basis for the free exercise of individual will.

Nietzsches emotionally charged defense of intellectual freedom and radial empowerment of mind as the maker and transformer of the collective fictions that shape human reality in a soulless mechanistic universe proved terribly influential on twentieth-century thought. Furthermore, Nietzsche sought to reinforce his view of the subjective character of scientific knowledge by appealing to an epistemological crisis over the foundations of logic and arithmetic that arose during the last three decades of the nineteenth century. Through a curious course of events, attempted by Edmund Husserl 1859-1938, a German mathematician and a principal founder of phenomenology, wherefor to resolve this crisis resulted in a view of the character of consciousness that closely resembled that of Nietzsche.

The philosophical postmodernists were correct in assuming that scientific knowledge exists in human subjective reality and wrong in assuming that this knowledge is not privileged in coordinating our experience with physical reality. As such, this is the scientific communities were correct in assuming that the mathematical description of nature is privileged and wrong in assuming that this description exists in some sense prior to or outside of human consciousness. Obviously, this suggests that the communicants of cultural stain should take responsibility for escalating the conflicting debate between those that are and those that should be, in other words, all deliberate efforts in the understanding in the interests of human survival be themselves clearly aware of why this is the case.

The best-known disciple of Husserl was Martin Heidegger, and the work of both figures greatly influenced that of the French atheistic existentialist Jean-Paul Sartre. The work of Husserl, Heidegger, and Sartre became foundational to that of the principal architects of philosophical postmodernism, and deconstructionist Jacques Lacan, Roland Barthes, Michel Foucault and Jacques Derrida. It obvious attribution of a direct linkage between the nineteenth-century crisis about the epistemological foundations of mathematical physics and the origin of philosophical postmodernism served to perpetuate the Cartesian two-world dilemma in an even more oppressive form. It also allows us better to understand the origins of cultural ambience and the ways in which they could resolve that conflict.

The mechanistic exemplar of the late in the nineteenth century began when Einstein came to know of his applicable abilities so marked and noted through his proven depictions, from which. Toward which time, that his studies were sustained within the physics, that from which time most physicists believed that it represented an eternal truth, however, Einstein was open to fresh ideas. Inspired by Machs critical mind, he demolished the Newtonian ideas of space and time and replaced them with new, relativistic notions.

Jean-Paul Sartre (1905-1980), was a French philosopher, dramatist, novelist, and political journalist, who was a leading exponent of existentialism. Jean-Paul Sartre helped to develop existential philosophy through his writings, novels, and plays. Much as much of the focus laid upon Sartres’ work on the dilemma of choice is faced by free individuals and on the challenge of creating meaning by acting responsibly in an indifferent world. In stating that man is condemned to be free, Sartre reminds us of the responsibility that accompanies human decisions.

Sartre was born in Paris, June 21, 1905, and educated at the Écôle Normale Supérieure in Paris, the University of Fribourg in Switzerland, and the French Institute in Berlin. He taught philosophy at various lycées from 1929 until the outbreak of World War II, when he was called into military service. In 1940-41 he was imprisoned by the Germans; after his release, he taught in Neuilly, a small but flourishing town in France, and later in Paris, he was an active member in the French Resistance. The German authorities, unaware of his underground activities, permitted the production of his antiauthoritarian play The Flies (1943; translated 1946) and the publication of his major philosophic work Being and Nothingness (1943; translated 1953). Sartre gave up teaching in 1945 and founded the political and literary magazine Les Temps Modernes, of which he became the editor in chief. Sartre was active after 1947 as an independent Socialist, critical of both the USSR and the United States in the so-called cold war years. Later, he supported Soviet positions but still frequently criticized Soviet policies. Most of his writing of the 1950s deals with literary and political problems. Sartre rejected the 1964 Nobel Prize in literature, explaining that to accept such an award would compromise his integrity as a writer.

Sartres’ philosophy is concerned entirely with the nature of human life, and the structures of consciousness. As a fault it gains expression in his novels and, lays as well as in more orthodox academic treatises, its immediate ancestor is the phenomenological tradition of his teachers, and Sartre can in most simply be seen as concerned with the rebutable charge of idealism as it is laid at the door of ‘phenomenonology’. The agent is not a spectator of the world, but like everything in the world, constituted by acts of intentionality and consciousness. Thus, constituted by the historically situated, but an agent whose own mode of locating itself in the world makes for responsibility and emotion. Sabre thus locales the essential nature of human existence in the capacity for choice, although choice, being equally incomparable with determinism and with the existence of a Kantian moral law, implies a synthesis of consciousness (being for itself) and the objective (being in itself) that is forever unstable. For all that was to come, Sartres philosophical transactions were to be combined with the phenomenology of the German philosopher Edmund Husserl, and those contributive efforts in metaphysics came from the German philosopher’s Georg Wilhelm Friedrich Hegel and Martin Heidegger, and the social theories of Karl Marx all were to adjoin of an organization through which a single view was to be called existentialism. This view, which relates philosophical theory to life, literature, psychology, and political action, stimulated so much popular interest that existentialism became a worldwide movement.

In his early philosophic work, Being and Nothingness, Sartre conceived humans as beings who create their own world by rebelling against authority and by accepting personal responsibility for their actions, unaided by society, traditional morality, or religious faith. Distinguishing between human existence and the nonhuman world, he maintained that human existence is characterized by nothingness, that is, by the capacity to negate and rebel. His theory of an existential psychoanalysis asserted the inescapable responsibility of all individuals for their own decisions and made the recognition of ones absolute freedom of choice the necessary condition for authentic human existence. His plays and novels express the belief that freedom and acceptance of personal responsibility are the main values in life and that individuals must rely on their creative powers rather than on social or religious authority.

In his later philosophic work, Critique of Dialectical Reason (1960; translated 1976), was a consolidated placement for France‘s leading existentialist philosopher? Sartre, at the same time, human behaviors rendered to social order and it portrayed, and legitimized, as an outcome of free-choice (consciousness) and Being in-itself (the non-conscious world). He rejects cental tenets of the rationalist and empiricist traditions, cabling the view that the mind or self is a thing or substance ‘Descartes’ substantialist illusion’ and claiming that consciousness does not contain ideas or representation of the material world. Sartre also attacks idealism in the forms associated with Berkeley and Kant, and concludes that his account of the relationship between consciousness and the world is neither realist nor idealist.

Sartre also discusses Being for-others. Which comprises the aspects of experience pertaining to interactions with other minds? Sartre’s rejection of ideas, and the denial of realism in the theory of perception was not, however, inconsistent with his claim to be neither realist nor idealist, since by ‘realist’ he means views which allow for the mutual independence or in-principle separability of mind and world. Against this Sartre emphasizes, after Heidegger, that perceptual experience has an active dimension, in that it is a way of interacting and dealing with the world, than a way of merely contemplating it (‘activity as spontaneous, unreflecting consciousness, constituted a certain existential stratum in the world). Consequently, he holds that experience is richer and open to more aspects of the world, than empiricist writers customarily claim.

Sartre argued that the influence of modern society over the individual is so great as to produce serialization, by which he meant loss of self. Individual power and freedom can only be regained through group revolutionary action. Despite this exhortation to revolutionary political activity, Sartre himself did not join the Communist Party, thus retaining the freedom to criticize the Soviet invasions of Hungary in 1956 and Czechoslovakia in 1968.

Nonetheless, the phenomenological claims are such that things as illusions and hallucinations, for which are normally cited as problems for direct realists. However, he describes the act of imaging as a ‘transformation’ of ‘psychic material’. This connects with his views that even a physical image such as a photograph of a tree does not figure as an object of consciousness when it is experienced as a tree-representation, rather than as a piece of colored card, but even so, the fact remains that the photograph continues to contribute to the character of the experience. Given this, it is hard to see how Sartre avoids positing a mental analogue of a photograph for episodes of mental imaging, and rejection of visual representations. It may be that the regarding imaging was debased and derivative perceptual knowledge, again, this merely raises more of the issues of perceptual illusion and hallucination, and the problem of reconciling them with direct realism. He died in Paris, April 15, 1980.

The part of the theory of framing designs or semiotics, that concern the relationship between speakers and their significancy of meaning to affix the action, gesture or word by which a common thought, or wish is exposed through signs. The study of the principles governing appropriate conversational moves is generally called pragmatics that application for pragmatics treats of special kinds of linguistic infection, such as interview and speech asking, nevertheless, the philosophical movement that has had a major impact on American culture from the late 19th century to the present. Pragmatism calls for ideas and theories to be tested in practice, by assessing whether acting upon the idea or theory produces desirable or undesirable results. According to pragmatists, all claims about truth, knowledge, morality, and politics must be tested in this way. Pragmatism has been critical of traditional Western philosophy, especially the notions that there are absolute truths and absolute values. Although pragmatism was popular for a time in France, England, and Italy, most observers believe that it encapsulates an American faith in know-how and practicality and an equally American continental distrust of abstract theories and ideologies.

Pragmatists regard all theories and institutions as tentative hypotheses and solutions. For this reason they believed that efforts to improve society, through such means as education or politics, must be geared toward problem solving and must be ongoing. Through their emphasis on connecting theory to practice, pragmatist thinkers attempted to transform all areas of philosophy, from metaphysics to ethics and political philosophy.

Pragmatism sought a middle ground between traditional ideas about the nature of reality and radical theories of nihilism and irrationalism, which had become popular in Europe in the late 19th century. Traditional metaphysics assumed that the world has a fixed, intelligible structure and that human beings can know absolute or objective truths about the world and about what constitutes moral behavior. Nihilism and irrationalism, on the other hand, denied those very assumptions and their certitude. Pragmatists today still try to steer a middle course between contemporary offshoots of these two extremes.

The ideas of the pragmatists were considered revolutionary when they first appeared. To some critics, pragmatism refusal to affirm any absolutes carried negative implications for society. For example, pragmatists do not believe that a single absolute idea of goodness or justice exists, but rather than these concepts are changeable and depend on the context in which they are being discussed. The absence of these absolutes, critics feared, could result in a decline in moral standards. The pragmatist’s denial of absolutes, moreover, challenged the foundations of religion, government, and schools of thought. As a result, pragmatism influenced developments in psychology, sociology, education, semiotics (the study of signs and symbols), and scientific method, as well as philosophy, cultural criticism, and social reform movements. Various political groups have also drawn on the assumptions of pragmatism, from the progressive movements of the early 20th century to later experiments in social reform.

Pragmatism is best understood in its historical and cultural context. It arose during the late 19th century, a period of rapid scientific advancement typified by the theories of British biologist Charles Darwin, whose theories suggested too many thinkers that humanity and society are in a perpetual state of progress. During this same period a decline in traditional religious beliefs and values accompanied the industrialization and material progress of the time. In consequence it became necessary to rethink fundamental ideas about values, religion, science, community, and individuality.

The three most important pragmatists are American philosophers’ Charles Sanders Peirce, William James, and John Dewey. Peirce was primarily interested in scientific method and mathematics; his objective was to infuse scientific thinking into philosophy and society, and he believed that human comprehension of reality was becoming ever greater and that human communities were becoming increasingly progressive. Peirce developed pragmatism as a theory of meaning - in particular, the meaning of concepts used in science. The meaning of the concept brittle, for example, is given by the observed consequences or properties that objects called brittle exhibit. For Peirce, the only rational way to increase knowledge was to form mental habits that would test ideas through observation, experimentation, or what he called inquiry. Many philosophers known as logical positivist, a group of philosophers who have been influenced by Peirce, believed that our evolving species was fated to get ever closer to Truth. Logical positivist emphasize the importance of scientific verification, rejecting the assertion of positivism that personal experience is the basis of true knowledge.

James moved pragmatism in directions that Peirce strongly disliked. He generalized Peirces doctrines to encompass all concepts, beliefs, and actions; he also applied pragmatist ideas to truth as well as to meaning. James was primarily interested in showing how systems of morality, religion, and faith could be defended in a scientific civilization. He argued that sentiment, as well as logic, is crucial to rationality and that the great issues of life - morality and religious belief, for example - are leaps of faith. As such, they depend upon what he called the will to believe and not merely on scientific evidence, which can never tell us what to do or what is worthwhile. Critics charged James with relativism (the belief that values depend on specific situations) and with crass expediency for proposing that if an idea or action works the way one intends, it must be right. But James can more accurately be described as a pluralist - someone who believes the world to be far too complex for any-one philosophy to explain everything.

Deweys philosophy can be described as a version of philosophical naturalism, which regards human experience, intelligence, and communities as ever-evolving mechanisms. Using their experience and intelligence, Dewey believed, human beings can solve problems, including social problems, through inquiry. For Dewey, naturalism led to the idea of a democratic society that allows all members to acquire social intelligence and progress both as individuals and as communities. Dewey held that traditional ideas about knowledge, truth, and values, in which absolutes are assumed, are incompatible with a broadly Darwinian world view in which individuals and society is progressing. In consequence, he felt that these traditional ideas must be discarded or revised. Indeed, for pragmatists, everything people know and do depend on a historical context and are thus tentative rather than absolute.

Many followers and critics of Dewey believe he advocated elitism and social engineering in his philosophical stance. Others think of him as a kind of romantic humanist. Both tendencies are evident in Deweys writings, although he aspired to synthesize the two realms.

The pragmatist’s tradition was revitalized in the 1980s by American philosopher Richard Rorty, who has faced similar charges of elitism for his belief in the relativism of values and his emphasis on the role of the individual in attaining knowledge. Interest has renewed in the classic pragmatists - Pierce, James, and Dewey - as an alternative to Rortys interpretation of the tradition.

In an ever-changing world, pragmatism has many benefits. It defends social experimentation as a means of improving society, accepts pluralism, and rejects’ dead dogmas. But a philosophy that offers no final answers or absolutes and that appears vague as a result of trying to harmonize opposites may also be unsatisfactory to some.

One of the five branches into which semiotics is usually divided into a study of meaning of words, and their relation as designed by the object studied, that if a language is provided with a truth-definition, this is a sufficient characterization of its concept of truth, there is no further regionally philological attribution as felt by its writing. The view is similar to the ‘disquotational theory’, however, an influential proposal is that this relationship as a truth-definition is best understood by attempting to provide that which will involve giving a full description for the language, which systematic effect terms and structure of different kinds have on the truth-conditions of sentences containing them. Signs, - that is, words, expressions, and sentences, and semantics tries to answer such questions as: What is the meaning of the expressioned word ‘X’? They do this by studying what signs, as well as how signs possess significance, . . . that is, how they are intended by orators who openly speak of how they designate (make reference to things and ideas), and how they are interpreted by recipients. The goal of semantics is to match the meanings of signs - what they stand for - with the process of assigning those meanings.

Semantics is studied from philosophical (pure) and linguistic (descriptive and theoretical) approaches, and an approach known as general semantics. Philosophers look at the behavior that goes with the process of meaning. Linguists study the elements or features of meaning as they are related in a linguistic system. General semanticists concentrate on meaning as influencing what people think and do.

These semantic approaches also have broader application. Anthropologists, through descriptive semantics, study what people categorize as culturally important. Psychologists draw on theoretical semantic studies that attempt to describe the mental process of understanding and to identify how people acquire meaning (as well as sound and structure) in language. Animal behaviorists research how and what other species communicate. Exponents of general semantics examine the different values (or connotations) of signs that supposedly mean the same thing, such as the victor at Jena and the loser at Waterloos, are forthwith in referring to Napoleon, also in a general semantic vein, is literarily critical of the prominent persuasions that had influenced by studies differentiating versed languages insofar as the explicit formalities that ordinary language and describing how literarily metaphors evoke feelings and attitudes.

In the late 19th century Michel Jules Alfred Breal, a French philologist, proposed a science of significations that would investigate how sense is attached to expressions and other signs. In 1910 the British philosophers’ Alfred North Whitehead and Bertrand Russell published Principia Mathematica, which strongly influenced the Vienna Circle, a group of philosophers who developed the rigorous philosophical approach known as logical positivism.

One of the leading figures of the Vienna Circle, the German philosopher Rudolf Carnap, made a major contribution to philosophical semantics by developing symbolic logic, a system for analyzing signs and what they designate. In logical positivism, meaning is a relationship between words and things, and its study is empirically based: Because language, ideally, is a direct reflection of reality, signs match things and facts. In symbolic logic, however, mathematical notation is used to state what signs designate and to do so more clearly and precisely than is possible in ordinary language. Symbolic logic is thus itself a language, specifically, a metalanguage (formal technical language) used to talk about an object language (the language that is the object of a given semantic study).

An object language has a speaker (for example, a French woman) using expressions (such as la plume rouge) to designate a meaning (in this case, to indicate a definite pen - a plume - and of the colour red - rouge, an easy partaking for remedial purposes). The full description of an object language in symbols is called the semiotic of that language. A language’s semiotic has the following aspects: (1) a semantic aspect, in which signs (words, expressions, sentences) are given specific designations; (2) a pragmatic aspect, in which the contextual relations between speakers and signs are indicated; and (3) a syntactic aspect, in which formal relations among the elements within signs (for example, among the sounds in a sentence) are indicated.

An interpreted language in symbolic logic is an object language together with rules of meaning that link signs and designations. Each interpreted sign has a truth condition - a condition that must be met in order for the sign to be true. A sign meaning is what the sign designates when its truth condition is satisfied. For example, the expression or sign the moon is a sphere is understood by someone who knows English; however, although it is understood, it may or may not be true. The expression is true if the thing it is extended to - the moon - is in fact, a circular orbital. To determine the sign’s truth value, one must look at the moon for purposes of self-consciousness.

The symbolic logic of logical positivist philosophy thus represents an attempt to get at meaning by way of the empirical verifiability of signs - by whether the truth of the sign can be confirmed by observing something in the real world. This attempt at understanding meaning has been only moderately successful. The Austrian-British philosopher Ludwig Wittgenstein rejected it in favor of his ordinary language philosophy, in which he asserted that thought is based on everyday language. Not all signs designate things in the world, he pointed out, nor can all signs be associated with truth values. In his approach to philosophical semantics, the rules of meaning are disclosed in how speech is used.

From ordinary-language philosophy has evolved the current theory of speech-act semantics. The British philosopher J. L. Austin claimed that, by speaking, a person performs an act, or does something (such as state, predict, or warn), and that meaning is found in what an expression does, in the act it performs. The American philosopher John R. Searle extended Austins ideas, emphasizing the need to relate the functions of signs or expressions to their social context. Searle asserted that speech encompasses at least three kinds of acts: (1) locutionary acts, in which things are said with a certain sense or reference (as in the moon is a sphere); (2) illocutionary acts, in which such acts as promising or commanding are performed by means of speaking; and (3) perlocutionary acts, in which the speaker, by speaking, does something to someone else (for example, angers, consoles, or persuades someone). The speaker’s intentions are conveyed by the illocutionary force that is given to the signs - that is, by the gestural simplicity in what is said. To be successfully meant, however, the signs must also be appropriate, sincere, consistent with the speaker’s general beliefs and conduct, and recognizable as meaningful by the hearer.

What has developed in philosophical semantics, then, is a distinction between truth-based semantics and speech-act semantics. Some critics of speech-act theory believe that it deals primarily with meaning in communication (as opposed to meaning in language) and thus is part of the pragmatic aspect of a language semiotic - that it relates to signs and to the knowledge of the world shared by speakers and hearers, rather than relating to signs and their designations (semantic aspect) or to formal relations among signs (syntactic aspect). These scholars hold that semantics should be restricted to assigning interpretations to signs alone - independent of a speaker and hearer.

Studies in descriptive semantics, were of what a distinction of a thing or state of affairs was any symptom or potent usage that concurs through its own content. The American philosopher Charles Sanders Peirce (1839-1914) described such that were artificial signs, but this is a mistake for symbols are not typically used to infer the presence of what they symbolize, nonetheless, only to represent them in their absence, or to express intentions or to conjure up thoughts and emotions centered upon them. The theory of this difference lies at the heart of the philosophy of language. For signs are differentiated in their meanings in particular languages. They aim, for instance, to identify what constitutes nouns or noun-phrases and verbs or verb-phrases. For some languages, such as English, this is done with subject-predicate analysis. For languages without clear-cut distinctions between nouns, verbs, and prepositions, it is possible to say what the signs mean by analyzing the structure of what are called propositions. In such an analysis, a sign is seen as an operator that combines with one or more arguments (also signs), often nominal argument (noun phrases) or, relates nominal arguments to other elements in the expression (such as prepositional phrases or adverbial phrases). For example, in the expression Bill gives Mary the book, gives is an operator that relates the arguments’ Bill, Mary, and the book.

Whether using subject-predicate analysis or propositional analysis, descriptive semanticists establish expression classes (classes of items that can substitute for one another within a sign) and classes of items within the conventional parts of speech (such as nouns and verbs). The resulting classes are thus defined in terms of syntax, and they also have semantic roles; that is, the items in these classes perform specific grammatical functions, and in so doing they establish meaning by predicating, referring, making distinctions among entities, relations, or actions. For example, the kiss belongs to an expression class with other items such as hit and sees, as well as to the conventional part of speech verbs, in which it is part of a subclass of operators requiring two arguments (an actor and a receiver). In Mary kissed John, the syntactic role of the kiss is to relate two nominal arguments (Mary and John), whereas its semantic role is to identify a type of action. Unfortunately for descriptive semantics, however, it is not always possible to find a one-to-one correlation of syntactic classes with semantic roles. For instance, John has the same semantic role - to identify a person - in the following two sentences: John is easy to please and John is eager to please. The syntactic role of John in the two sentences, however, is different: In the first, John is the receiver of an action; in the second, John is the actor.

Linguistic semantics is also used by anthropologists called ethnoscientists to conduct formal semantic analysis (componential analysis) to determine how expressed signs - usually single words as vocabulary items called lexemes - in a language are related to the perceptions and thoughts of the people who speak the language. Componential analysis tests the idea that linguistic categories influence or determine how people view the world; this idea is called the Whorf hypothesis after the American anthropological linguist Benjamin Lee Whorf, who proposed it. In componential analysis, lexemes that have a common range of meaning constitute a semantic domain. Such a domain is characterized by the distinctive semantic features (components) that differentiate individual lexemes in the domain from one another, and also by features shared by all the lexemes in the domain. Such componential analysis points out, for example, that in the domain seat in English, the lexemes chair, sofa, loveseat, and bench can be distinguished from one another according too many people who have accommodatingly conformed of whether a back support is included. At the same time, all these lexemes share a common component, or features the meaning of something on which to put in a seating position.

Linguistic pursuants, in such a componential analysis hope to identify a universal set class of such semantic features, from which are drawn the different sets of features that characterize different languages. This idea of universal semantic features has been applied to the analysis of systems of myth and kinship in various cultures by the French anthropologist Claude Lévi-Strauss. He showed that people organize their societies and interpret their place in these societies in ways that, despite apparent differences, have remarkable underlying similarities.

Linguists concerned with theoretical semantics are looking for a general theory of meaning in language. To such linguists, known as transformational-generative grammarians, meaning is part of the linguistic knowledge or competence that all humans possess. A generative grammar as a model of linguistic competence has a phonological (sound-system), a syntactic, and a semantic component. The semantic component, as part of a generative theory of meaning, is envisioned as a system of rules that govern how interpretable signs are interpreted and determine that other signs (such as Colorless green ideas sleep furiously), although grammatical expressions, are meaningless - semantically blocked. The rules must also account for how a sentence as such as them passed the port at midnight can have at least two interpretations.

Generative semantics grew out of proposals to explain a speaker’s ability to produce and understand new expressions where grammar or syntax fails. Its goal is to explain why and how, for example, a person understands at first hearing that the sentence Colorless green ideas sleep furiously has no meaning, even though it follows the rules of English grammar; or how, in hearing a sentence with two possible interpretations, such that those who passed the port at midnight, one ought to make up one’s mind with which meaning applies.

In generative semantics, the idea developed that all information needed to semantically interpret a sign (usually a sentence) is contained in the sentences underlying grammatical or syntactic deep structure. The deep structure of a sentence involves lexemes (understood as words or vocabulary items composed of bundles of semantic features selected from the proposed universal set of semantic features). On the sentences surface (that is, when it is spoken) these lexemes will appear as nouns, verbs, adjectives, and other parts of speech - that is, as vocabulary items. When the sentence is formulated by the speaker, semantic roles (such as subject, the object, predicates) are assigned to the lexemes; the listener hears the spoken sentence and interprets the semantic features that are meant.

Whether deep structure and semantic interpretation are distinct from one another is a matter of controversy. Most generative linguists agree, however, that a grammar should generate the set of semantically enabling, by which formed expressions that are possible in a given language, in that the grammar should associate a semantic interpretation with each expression.

Another subject of debate is whether semantic interpretation should be understood as syntactically based, that is, coming from sentences of a deep structure, or whether it should be seen as semantically debased and founded, according to Noam Chomsky, an American scholar who is particularly influential in this field. It is possible, however, - in a syntactically based theory - for which surface structures and depthful restrictions may jointly determine the semantic interpretation of an expression.

The focus of general semantics is how people evaluate words and how that evaluation influences their behavior. Begun by the Polish American linguist Alfred Korzybski and long associated with the American semanticist and politician S. I. Hayakawa, general semantics has been used in efforts to make people aware of dangers inherent in treating words as more than symbols. It has been extremely popular with writers who use language to influence peoples ideas. In their work, these writers use general-semantics guidelines for avoiding loose generalizations, rigid attitudes, inappropriate finality, and imprecision. Some philosophers and linguists, however, have criticized general semantics as lacking scientific rigor, and the approach has declined in popularity.

Positivism, system of philosophy based on experience and empirical knowledge of natural phenomena, in which metaphysics and theology are regarded as inadequate and imperfect systems of knowledge. The doctrine was first called positivism by the 19th-century French mathematician and philosopher Auguste Comte (1798-1857), but some of the positivist concepts may be traced to the British philosopher David Hume, the French philosopher Duc de Saint-Simon, and the German philosopher Immanuel Kant.

Comte chose the word positivism on the ground that it indicated the reality and constructive tendency that he claimed for the theoretical aspect of the doctrine. He was, in the main, interested in a reorganization of social life for the good of humanity through scientific knowledge, and thus controls of natural forces. The two primary components of positivism, the philosophy and the polity (or a program of individual and social conduct), were later welded by Comte into a whole under the conception of a religion, in which humanity was the object of worship. A number of Comtes disciples refused, however, to accept this religious development of his philosophy, because it seemed to contradict the original positivist philosophy. Many of doctrines that Comtes was later to adjustively adapt and developed by the British social philosophers John Stuart Mill and Herbert Spencer and by the Austrian philosopher and physicist Ernst Mach.

During the early 20th century a group of philosophers who were concerned with developments in modern science rejected the traditional positivist ideas that held personal experience to be the basis of true knowledge and emphasized the importance of scientific verification. This group came to be known as logical positivist, and it included the Austrian Ludwig Wittgenstein and the British Bertrand Russell and G. E. Moore. It was Wittgensteins Tractatus Logico-philosophicus (1921; German-English parallels text, 1922) that proved to be of decisive influence in the rejection of metaphysical doctrines for their meaninglessness and the acceptance of empiricism as a matter of logical necessity.

The positivist today, who has rejected this so-called Vienna school of philosophy, prefers to call themselves logical empiricist in order to dissociate themselves from the emphasis of the earlier thinkers on scientific verification. They maintain that the verification principle itself is philosophically unverifiable.

Bertrand Arthur William Russell (1872-1970), British philosopher, mathematician, and Nobel laureate, who, as a positivist might befittingly bring about an emphasis on logical analysis that has influenced the course of 20th-century schools of thought. In the early 20th century British mathematician and philosopher Bertrand Russell, along with British mathematician and philosopher Alfred North Whitehead, attempted to demonstrate that mathematics and numbers can be understood as groups of concepts, or classes. Russell and Whitehead tried to show that mathematics is closely related to logic and, in turn, that ordinary sentences can be logically analyzed using mathematical symbols for words and phrases. This idea resulted in a new symbolic language, used by Russell in a field he termed philosophical logic, in which philosophical propositions were reformulated and examined according to his symbolic logic.

Born in Trelleck, Wales, on May 18, 1872, Russell was educated at Trinity College, University of Cambridge. After graduation in 1894, he traveled in France, Germany, and the United States and was then made a fellow of Trinity College. From an early age he developed a strong sense of social consciousness; at the same time, he involved himself in the study of logical and mathematical questions, which he had made his special fields and on which he was called to lecture at many institutions throughout the world. He achieved prominence with his first major work, The Principles of Mathematics (1902), in which he attempted to remove mathematics from the realm of abstract philosophical notions and to give it a precise scientific framework.

Russell then collaborated for eight years with the British philosopher and mathematician Alfred North Whitehead to produce the monumental work Principia Mathematica (three volumes, 1910-1913). This work showed that mathematics can be stated in terms of the concepts of general logic, such as class and membership in a class. It became a masterpiece of rational thought. Russell and Whitehead proved that numbers can be defined as classes of a certain type, and in the process they developed logic concepts and a logic notation that established symbolic logic as an important specialization within the field of philosophy. In his next major work, The Problems of Philosophy (1912), Russell borrowed from the fields of sociology, psychology, physics, and mathematics to refute the tenets of idealism, the dominant philosophical school of the period, which held that all objects and experiences are the product of the intellect. Russell, a realist, believed that objects perceived by the senses have an inherent reality independent of the mind.

Russell criticized both adherents, whose participation involved of World War I (1914-1918), and for his uncompromising stand he was fined, imprisoned, and deprived of his teaching post at Cambridge. In prison he wrote Introduction to Mathematical Philosophy (1919), combining the two areas of knowledge he regarded as inseparable. After the war he visited the Russian Soviet Federated Socialist Republic, and in his book Practice and Theory of Bolshevism (1920) he expressed his disappointment with the form of socialism practiced there. He felt that the methods used to achieve a Communist system was intolerable and that the results obtained were not worth the price paid.

Russell taught at Beijing University in China during 1921 and 1922. From 1928 to 1932, after he returned to England, he conducted the private, highly progressive Beacon Hill School for young children. From 1938 to 1944 he taught at various educational institutions in the United States. He was barred, however, from teaching at the College of the City of New York (now City College of the City University of New York) by the state supreme court because of his attacks on religion in such works as What I Believe (1925) and his advocacy of sexual freedom, expressed in Manners and Morals (1929).

Russell returned to England in 1944 and was reinstated as a fellow of Trinity College. Although he abandoned pacifism to support the Allied cause in World War II (1939-1945), he became an ardent and active opponent of nuclear weapons. In 1949 he was awarded the Order of Merit by King George VI. Russell received the 1950 Nobel Prize for Literature and was cited as the champion of humanity and freedom of thought. He led a movement in the late 1950s advocating unilateral nuclear disarmament by Britain, and at the age of 89 he was imprisoned after an antinuclear demonstration. He died on February 2, 1970.

In addition to his earlier work, Russell also made a major contribution to the development of logical positivism, a strong philosophical movement of the 1930s and 1940s. The major Austrian philosopher Ludwig Wittgenstein, at one time Russells student at Cambridge, was strongly influenced by his original concept of logical atomism. In his search for the nature and limits of knowledge, Russell was a leader in the revival of the philosophy of empiricism in the larger field of epistemology. In Our Knowledge of the External World (1926) and Inquiry into Meaning and Truth (1962), he attempted to explain all factual knowledge as constructed out of immediate experiences. Among his other books is The ABC of Relativity (1925), Education and the Social Order (1932), A History of Western Philosophy (1945), The Impact of Science upon Society (1952), My Philosophical Development (1959), War Crimes in Vietnam (1967), and The Autobiography of Bertrand Russell (three volumes, 1967-1969).

Analytic and Linguistic philosophy begins in the 20th-century as philosophical movement, it is dominant in Britain and the United States since World War II, and aims to clarify language and analyze the concepts expressed in it. The movement has been given a variety of designations, including linguistic analysis, logical empiricism, logical positivism, Cambridge analysis, and Oxford philosophy. The last two labels are derived from the universities in England where this philosophical method has been particularly influential. Although no specific doctrines or tenets are accepted by the movement as a whole, analytic and linguistic philosophers agree that the proper activity of philosophy is clarifying language, or, as some prefer, clarifying concepts. The aim of this activity is to settle philosophical disputes and resolve philosophical problems, which, it is argued, originates in linguistic confusion.

A considerable diversity of views exists among analytic and linguistic philosophers regarding the nature of conceptual or linguistic analysis. Some have been primarily concerned with clarifying the meaning of specific words or phrases as an essential step in making philosophical assertions clear and unambiguous. Others have been more concerned with determining the general conditions that must be met for any linguistic utterance to be meaningful; their intent is to establish a criterion that will distinguish between meaningful and nonsensical sentences. Still other analysts have been interested in creating formal, symbolic languages that are mathematical in nature. Their claim is that philosophical problems can be more effectively dealt with once they are formulated in a rigorous logical language.

By contrast, many philosophers associated with the movement have focused on the analysis of ordinary, or natural, language. Difficulties arise when concepts such as time and freedom, for example, are considered apart from the linguistic context in which they normally appear. Attention to language as it is ordinarily used is the key, it is argued, to resolving many philosophical puzzles.

Many experts believe that philosophy as an intellectual discipline originated with the work of Plato, one of the most celebrated philosophers in history. The Greek thinker had an immeasurable influence on Western thought. However, Platos expression of ideas in the form of dialogues - his dialectical method, used most famously by his teacher Socrates - has led to difficulties in interpreting some of the finer points of his thoughts. The issue of what exactly Plato meant to say is addressed in the following excerpt by author R. M. Hare.

Linguistic analysis as a method of philosophy is as old as the Greeks. Several of the dialogues of Plato, for example, are specifically concerned with clarifying terms and concepts. Nevertheless, this style of philosophizing has received dramatically renewed emphasis in the 20th century. Influenced by the earlier British empirical tradition of John Locke, George Berkeley, David Hume, and John Stuart Mill and by the writings of the German mathematician and philosopher Gottlob Frége, the 20th-century English philosophers’ G. E. Moore and Bertrand Russell became the founders of this contemporary analytic and linguistic trend. As students together at the University of Cambridge, Moore and Russell rejected Hegelian idealism, particularly as it was reflected in the work of the English metaphysician F. H. Bradley, who held that nothing is completely real except the Absolute. In their opposition to idealism and in their commitment to the view that careful attention to language is crucial in philosophical inquiry, and they set the mood and style of philosophizing for much of the 20th century English-speaking world.

For Moore, philosophy was first and foremost analysis. The philosophical task involves clarifying puzzling propositions or concepts by indicating fewer puzzling propositions or concepts to which the originals are held to be logically equivalent. Once this task has been completed, the truth or falsity of problematic philosophical assertions can be determined more adequately. Moore was noted for his careful analyses of such puzzling philosophical claims as time is unreal, analyses that then were to benefit from a store of ardently assistive in the determining of truth of such assertions.

Russell, strongly influenced by the precision of mathematics, was concerned with developing an ideal logical language that would accurately reflect the nature of the world. Complex propositions, Russell maintained, can be resolved into their simplest components, which he called atomic propositions. These propositions refer to atomic facts, the ultimate constituents of the universe. The metaphysical views based on this logical analysis of language and the insistence that meaningful propositions must correspond to facts constitute what Russell called logical atomism. His interest in the structure of language also led him to distinguish between the grammatical form of a proposition and its logical form. The statements John is good and John is tall have the same grammatical form but different logical forms. Failure to recognize this would lead one to treat the property goodness as if it were a characteristic of John in the same way that the property tallness is a characteristic of John. Such failure results in philosophical confusion.

Austrian-born philosopher Ludwig Wittgenstein was one of the most influential thinkers of the 20th century. With his fundamental work, Tractatus Logico-philosophicus, published in 1921, he became a central figure in the movement known as analytic and linguistic philosophy.

Russells work in mathematics attracted to Cambridge, and the Austrian philosopher Ludwig Wittgenstein, who became a central figure in the analytic and linguistic movement. In his first major work, Tractatus Logico-Philosophicus (1921; translated 1922), in which he first presented his theory of language, Wittgenstein argued that all philosophy is a critique of language and that philosophy aims at the logical clarification of thoughts. The results of Wittgensteins analysis resembled Russells logical atomism. The world, he argued, is ultimately composed of simple facts, which it is the purpose of language to picture. To be meaningful, statements about the world must be reducible to linguistic utterances that have a structure similar to the simple facts pictured. In this early Wittgensteinian analysis, only propositions that picture facts—the propositions of science - are considered factually meaningful. Metaphysical, theological, and ethical sentences were judged to be factually meaningless.

Influenced by Russell, Wittgenstein, Ernst Mach, and others, a group of philosophers and mathematicians in Vienna in the 1920s initiated the movement known as logical positivism. Led by Moritz Schlick and Rudolf Carnap, the Vienna Circle initiated one of the most important chapters in the history of analytic and linguistic philosophy. According to the positivist, the task of philosophy is the clarification of meaning, not the discovery of new facts (the job of the scientists) or the construction of comprehensive accounts of reality (the misguided pursuit of traditional metaphysics).

The positivist divided all meaningful assertions into two classes: analytic propositions and empirically verifiable ones. Analytic propositions, which include the propositions of logic and mathematics, are statements the truth or falsity of which depend altogether on the meanings of the terms constituting the statement. An example would be the proposition two plus two equals four. The second class of meaningful propositions includes all statements about the world that can be verified, at least in principle, by sense experience. Indeed, the meaning of such propositions is identified with the empirical method of their verification. This verifiability theory of meaning, the positivist concluded, would demonstrate that scientific statements are legitimate factual claims and that metaphysical, religious, and ethical sentences are factually lacking contents that could or should be present. The ideas of logical positivism were made popular in England by the publication of A. J. Ayers Language, Truth and Logic in 1936.

The positivist verifiability theory of meaning came under intense criticism by philosophers such as the Austrian-born British philosopher Karl Popper. Eventually this narrow theory of meaning yielded to a broader understanding of the nature of language. Again, an influential figure was Wittgenstein. Repudiating many of his earlier conclusions in the Tractatus, he initiated a new line of thought culminating in his posthumously published Philosophical Investigations (1953; translated 1953). In this work, Wittgenstein argued that once attention is directed to the way language is actually used in ordinary discourse, the variety and flexibility of language become clear. Propositions do much more than simply picture facts.

This recognition led to Wittgensteins influential concept of language games. The scientist, the poet, and the theologian, for example, are involved in different language games. Moreover, the meaning of a proposition must be understood in its context, that is, in terms of the rules of the language game of which that proposition is a part. Philosophy, concluded Wittgenstein, is an attempt to resolve problems that arise as the result of linguistic confusion, and the key to the resolution of such problems is ordinary language analysis and the proper use of language.

Finally, for which Wittgenstein comes as a particular note for his contribution to the movement known as analytic and linguistic philosophy. He was born in Vienna on April 26, 1889, Wittgenstein was raised in a wealthy and cultured family. After attending schools in Linz and Berlin, he went to England to study engineering at the University of Manchester. His interest in pure mathematics led him to Trinity College, University of Cambridge, to study with Bertrand Russell. There he turned his attention to philosophy. By 1918, Ludwig Wittgenstein’s (1889-1951) work of the early period. Culminating in the completion in the Tractatus Logico-philosophicus (1921; translated 1922), and the late period from 1929 until his death, whose most famous expression is in the act, process, or instance of expressing in words the manifestations in one that calls to mind another that is oftentimes symbolically the given expression to a thought or an emotion that is viewed as freely phrased. The Philosophical investigations, published in 1953, but collected from notebooks and lecture notes. As both are dominated by as concern with the nature of language. The very implications in the early works language = is treated in relative abstraction from the activities of human beings, however, the Tractatus was a major influence on logical positivism, as the Tractus moves to a denial of cognitive meaning to sentences whose function does fit into its conception with ethics, or meaning, or the self. Doctrine s about logical form are amongst the things that can be shown, but not said,’wherefore, we cannot speak, thereof we must be silent.

The most sustaining and influential application of such are the idea that was in the philosophy of mind, justly as Wittgenstein explored the roles that identify with the self-contemplation, or sensations, or in intension, or beliefs actually play in our social lives, in order to undermine the Cartesian picture that the functions to describe the goings-on in an inner theater of which the subject is the lone spectator. Passages that subsequently become known as the ‘rule’ following consideration and the ‘private’ language argument are among the functional topics of modern philosophy of language and mind, although their precise interpretation is endlessly controversial.

Subsequently, he turned from philosophy and for several years taught elementary school in an Austrian village. In 1929 he returned to Cambridge to resume his work in philosophy and was appointed to the faculty of Trinity College. Soon he began to reject certain conclusions of the Tractatus and to develop the position reflected in his Philosophical Investigations (pub. posthumously 1953; translated 1953). Wittgenstein retired in 1947; he died in Cambridge on April 29, 1951. A sensitive, intense man who often sought solitude and was frequently depressed, Wittgenstein abhorred pretense and was noted for his simple style of life and dress. The philosopher was forceful and confident in personality, however, and he exerted considerable influence on those with whom he came in contact.

Wittgensteins philosophical life may be divided into two distinct phases: an early period, represented by the Tractatus, and a later period, represented by the Philosophical Investigations. Throughout most of his life, however, Wittgenstein consistently viewed philosophy as linguistic or conceptual analysis. In the Tractatus he argued that philosophy aims at the logical clarification of thoughts. In the Philosophical Investigations, however, he maintained that philosophy is a battle against the bewitchment of our intelligence by means of language.

Language, Wittgenstein argued in the Tractatus, is composed of complex propositions that can be analyzed into fewer complex propositions until one arrives at simple or elementary propositions. Correspondingly, the world is composed of complex facts that can be analyzed into fewer complex facts until one arrives at simple, or atomic, facts. The world is the totality of these facts. According to Wittgensteins picture theory of meaning, it is the nature of elementary propositions logically to picture atomic facts, or states of affairs. He claimed that the nature of language required elementary propositions, and his theory of meaning required that there be atomic facts pictured by the elementary propositions. On this analysis, only propositions that picture facts - the propositions of science - are considered cognitively meaningful. Metaphysical and ethical statements are not meaningful assertions. The logical positivist associated with the Vienna Circle was greatly influenced by this conclusion.

Wittgenstein came to believe, however, that the narrow view of language reflected in the Tractatus was mistaken. In the Philosophical Investigations he argued that if one actually looks to see how language is used, the variety of linguistic usage becomes clear. Words are like tools, and just as tools serve different functions, so linguistic expressions serve many functions. Although some propositions are used to picture facts, others are used to command, question, pray, thank, curse, and so on. This recognition of linguistic flexibility and variety led to Wittgensteins concept of a language game and to the conclusion that people play different language games. The scientist, for example, is involved in a different language game than the theologian. Moreover, the meaning of a proposition must be understood in terms of its context, that is, in terms of the rules of the game through which its proposition is a part. The key to the resolution of philosophical puzzles is the therapeutic process of examining and describing language in use.

Once again, the psychology proven attempts are well grounded to evolutionary principles, in which a variety of higher mental functions may be adaptations, forced in response to selection pressures on the human populations through evolutionary time. Candidates for such theorizing include material and paternal motivations, capacities for love and friendship, the development of language as a signalling system cooperative and aggressive, our emotional repertoire, our moral and reactions, including the disposition to detect and punish those who cheat on agreements or who free-ride on =the work of others, our cognitive structures, nd many others. Evolutionary psychology goes hand-in-hand with neurophysiological evidence about the underlying circuitry in the brain which subserves the psychological mechanisms it claims to identify. The approach was foreshadowed by Darwin himself, and William James, as well as the sociology of E.O. Wilson. The terms of use are applied, more or less aggressively, especially to explanations offered in sociobiology and evolutionary psychology.

Another assumption that is frequently used to legitimate the real existence of forces associated with the invisible hand in neoclassical economics derives from Darwins view of natural selection as a war-like competing between atomized organisms in the struggle for survival. In natural selection as we now understand it, cooperation appears to exist in complementary relation to competition. Complementary relationships between such results are emergent self-regulating properties that are greater than the sum of parts and that serve to perpetuate the existence of the whole.

According to E.O Wilson, the human mind evolved to believe in the gods and people need a sacred narrative to have a sense of higher purpose. Yet it is also clear that the gods in his view are merely human constructs and, therefore, there is no basis for dialogue between the world-view of science and religion. Science for its part, said Wilson, will test relentlessly every assumption about the human condition and in time uncover the bedrock of the moral a religious sentiment. The eventual result of the competition between the other, will be the secularization of the human epic and of religion itself.

Man has come to the threshold of a state of consciousness, regarding his nature and his relationship to te Cosmos, in terms that reflects reality. By using the processes of nature as metaphor, to describe the forces by which it operates upon and within Man, we come as close to describing reality as we can within the limits of our comprehension. Men will be very uneven in their capacity for such understanding, which, naturally, differs for different ages and cultures, and develops and changes over the course of time. For these reasons it will always be necessary to use metaphor and myth to provide comprehensible guides to living. In thus way, Mans imagination and intellect play vital roles on his survival and evolution.

Since so much of life both inside and outside the study is concerned with finding explanations of things, it would be desirable to have a concept of what counts as a good explanation from bad. Under the influence of logical positivist approaches to the structure of science, it was felt that the criterion ought to be found in a definite logical relationship between the exlanans (that which does the explaining) and the explanandum (that which is to be explained). The approach culminated in the covering law model of explanation, or the view that an event is explained when it is subsumed under a law of nature, that is, its occurrence is deducible from the law plus a set of initial conditions. A law would itself be explained by being deduced from a higher-order or covering law, in the way that Johannes Kepler(or Keppler, 1571-1630), was by way of planetary motion that the laws were deducible from Newtons laws of motion. The covering law model may be adapted to include explanation by showing that something is probable, given a statistical law. Questions for the covering law model include querying for the covering laws are necessary to explanation (we explain whether everyday events without overtly citing laws): Querying whether they are sufficient (it may not explain an event just to say that it is an example of the kind of thing that always happens). And querying whether a purely logical relationship is adapted to capturing the requirements, we make of explanations. These may include, for instance, that we have a feel for what is happening, or that the explanation proceeds in terms of things that are familiar to us or unsurprising, or that we can give a model of what is going on, and none of these notions is captured in a purely logical approach. Recent work, therefore, has tended to stress the contextual and pragmatic elements in requirements for explanation, so that what counts as good explanation given one set of concerns may not do so given another.

The argument to the best explanation is the view that once we can select the best of any in something in explanations of an event, then we are justified in accepting it, or even believing it. The principle needs qualification, since something it is unwise to ignore the antecedent improbability of a hypothesis which would explain the data better than others, e.g., the best explanation of a coin falling heads 530 times in 1,000 tosses might be that it is biassed to give a probability of heads of 0.53 but it might be more sensible to suppose that it is fair, or to suspend judgement.

In a philosophy of language is considered as the general attempt to understand the components of a working language, the relationship that understanding the speaker has to its elements, and the relationship they bear to the world. The subject therefore embraces the traditional division of semiotic into syntax, semantics, and pragmatics. The philosophy of language thus mingles with the philosophy of mind, since it needs an account of what it is in our understanding that enables us to use language. It so mingles with the metaphysics of truth and the relationship between sign and object. Much as much is that the philosophy in the 20th century, has been informed by the belief that philosophy of language is the fundamental basis of all philosophical problems, in that language is the distinctive exercise of mind, and the distinctive way in which we give shape to metaphysical beliefs. Particular topics will include the problems of logical form? And the basis of the division between syntax and semantics, as well as problems of understanding the number and nature of specifically semantic relationships such as meaning, reference, predication, and quantification. Pragmatics includes that of speech acts, while problems of rule following and the indeterminacy of translation infect philosophies of both pragmatics and semantics.

On this conception, to understand a sentence is to know its truth-conditions, and, yet, in a distinctive way the conception has remained central that those who offer opposing theories characteristically define their position by reference to it. The Concepcion of meaning s truth-conditions needs not and should not be advanced for being in itself as complete account of meaning. For instance, one who understands a language must have some idea of the range of speech acts contextually performed by the various types of a sentence in the language, and must have some idea of the insufficiencies of various kinds of speech acts. The claim of the theorist of truth-conditions should rather be targeted on the notion of content: If an indicative sentence differs in what they strictly and literally say, then this difference is fully accounted for by the difference in the truth-conditions.

The meaning of a complex expression is a function of the meaning of its constituent. This is just as a sentence of what it is for an expression to be semantically complex. It is one of the initial attractions of the conception of meaning truth-conditions tat it permits a smooth and satisfying account of the way in which the meaning of s complex expression is a function of the meaning of its constituents. On the truth-conditional conception, to give the meaning of an expression is to state the contribution it makes to the truth-conditions of sentences in which it occurs. For singular terms - proper names, indexical, and certain pronouns - this is done by stating the reference of the terms in question. For predicates, it is done either by stating the conditions under which the predicate is true of arbitrary objects, or by stating the conditions under which arbitrary atomic sentences containing it is true. The meaning of a sentence-forming operator is given by stating its contribution to the truth-conditions of as complex sentence, as a function of the semantic values of the sentences on which it operates.

The theorist of truth conditions should insist that not every true statement about the reference of an expression is fit to be an axiom in a meaning-giving theory of truth for a language, such is the axiom: London refers to the city in which there was a huge fire in 1666, is a true statement about the reference of London. It is a consequent of a theory which substitutes this axiom for no different a term than of our simple truth theory that London is beautiful is true if and only if the city in which there was a huge fire in 1666 is beautiful. Since a subject can understand the name London without knowing that last-mentioned truth condition, this replacement axiom is not fit to be an axiom in a meaning-specifying truth theory. It is, of course, incumbent on a theorised meaning of truth conditions, to state in a way which does not presuppose any previous, non-truth conditional conception of meaning

Among the many challenges facing the theorist of truth conditions, two are particularly salient and fundamental. First, the theorist has to answer the charge of triviality or vacuity, second, the theorist must offer an account of what it is for a persons language to be truly describable by as semantic theory containing a given semantic axiom.

Since the content of a claim that the sentence Paris is beautiful are true amounts to no more than the claim that Paris is beautiful, we can trivially describers understanding a sentence, if we wish, as knowing its truth-conditions, but this gives us no substantive account of understanding whatsoever. Something other than grasp of truth conditions must provide the substantive account. The charge rests upon what has been called the redundancy theory of truth, the theory which, somewhat more discriminatingly. Horwich calls the minimal theory of truth. Its conceptual representation that the concept of truth is exhausted by the fact that it conforms to the equivalence principle, the principle that for any proposition p, it is true that p if and only if P. Many different philosophical theories of truth will, with suitable qualifications, except that equivalence principle. The distinguishing feature of the minimal theory is its claim that the equivalence principle exhausts the notion of truth. It is now widely accepted, both by opponents and supporters of truth conditional theories of meaning, that it is inconsistent to accept both minimal theory of ruth and a truth conditional account of meaning. If the claim that the sentence Paris is beautiful is true is exhausted by its equivalence to the claim that Paris is beautiful, it is circular to try of its truth conditions. The minimal theory of truth has been endorsed by the Cambridge mathematician and philosopher Plumpton Ramsey (1903-30), and the English philosopher Jules Ayer, the later Wittgenstein, Quine, Strawson. Horwich and - confusing and inconsistently if this article is correct - Frége himself. But is the minimal theory correct?

The minimal theory treats instances of the equivalence principle as definitional of truth for a given sentence, but in fact, it seems that each instance of the equivalence principle can itself be explained. The truths from which such an instance as: London is beautiful is true if and only if London is beautiful. This would be a pseudo-explanation if the fact that London refers to London consists in part in the fact that London is beautiful has the truth-condition it does. But it is very implausible, it is, after all, possible to understand the name London without understanding the predicate is beautiful.

Sometimes, however, the counterfactual conditional is known as subjunctive conditionals, insofar as a counterfactual conditional is a conditional of the form if p were to happen q would, or if p was to have happened q would have happened, where the supposition of p is contrary to the known fact that not-p. Such assertions are nevertheless, useful if you broke the bone, the X-ray would have looked different, or if the reactors were to fail, this mechanism wold clicks in are important truths, even when we know that the bone is not broken or are certain that the reactor will not fail. It is arguably distinctive of laws of nature that yield counterfactual (if the metal were to be heated, it would expand), whereas accidentally true generalizations may not. It is clear that counterfactuals cannot be represented by the material implication of the propositional calculus, since that conditionals come out true whenever p is false, so there would be no division between true and false counterfactual.

Although the subjunctive form indicates some counterfactual, in many contexts it does not seem to matter whether we use a subjunctive form, or a simple conditional form: If you run out of water, you will be in trouble seems equivalent to if you were to run out of water, you would be in trouble, in other contexts there is a big difference: If Oswald did not kill Kennedy, someone else did is clearly true, whereas if Oswald had not killed Kennedy, someone would have is most probably false.

The best-known modern treatment of counterfactuals is that of David Lewis, which evaluates them as true or false according to whether q is true in the most similar possible worlds to ours in which p is true. The similarity-ranking this approach needs have proved controversial, particularly since it may need to presuppose some notion of the same laws of nature, whereas art of the interest in counterfactuals is that they promise to illuminate that notion. There is a growing awareness that the classification of conditionals is an extremely tricky business, and categorizing them as counterfactuals or does not be of limited use.

The pronouncing of any conditional; preposition of the form if p then Q. The condition hypothesizes, P. Its called the antecedent of the conditional, and q the consequent. Various kinds of conditional have been distinguished. The weaken in that of material implication, merely telling us that with not-p. or q. stronger conditionals include elements of modality, corresponding to the thought that if p is true then q must be true. Ordinary language is very flexible in its use of the conditional form, and there is controversy whether, yielding different kinds of conditionals with different meanings, or pragmatically, in which case there should be one basic meaning which case there should be one basic meaning, with surface differences arising from other implicatures.

We now turn to a philosophy of meaning and truth, for which it is especially associated with the American philosopher of science and of language (1839-1914), and the American psychologist philosopher William James (1842-1910), wherefore the study in Pragmatism is given to various formulations by both writers, but the core is the belief that the meaning of a doctrine is the same as the practical effects of adapting it. Peirce interpreted of theocratical sentence ids only that of a corresponding practical maxim (telling us what to do in some circumstance). In James the position issues in a theory of truth, notoriously allowing that belief, including for example, belief in God, is the widest sense of the works satisfactorily in the widest sense of the word. On Jamess view almost any belief might be respectable, and even rue, provided it works (but working is no simple matter for James). The apparent subjectivist consequences of tis were wildly assailed by Russell (1872-1970), Moore (1873-1958), and others in the early years of the 20 century. This led to a division within pragmatism between those such as the American educator John Dewey (1859-1952), whose humanistic conception of practice remains inspired by science, and the more idealistic route that especially by the English writer F.C.S. Schiller (1864-1937), embracing the doctrine that our cognitive efforts and human needs actually transform the reality that we seek to describe. James often writes as if he sympathizes with this development. For instance, in The Meaning of Truth (1909), he considers the hypothesis that other people have no minds (dramatized in the sexist idea of an automatic sweetheart or female zombie) and remarks hat the hypothesis would not work because it would not satisfy our egoistic craving for the recognition and admiration of others. The implication that this is what makes it true that the other persons have minds in the disturbing part.

Modern pragmatists such as the American philosopher and critic Richard Rorty (1931-) and some writings of the philosopher Hilary Putnam (1925-) who has usually tried to dispense with an account of truth and concentrate, as perhaps James should have done, upon the nature of belief and its relations with human attitude, emotion, and need. The driving motivation of pragmatism is the idea that belief in the truth on te one hand must have a close connection with success in action on the other. One way of cementing the connection is found in the idea that natural selection must have adapted us to be cognitive creatures because beliefs have effects, as they work. Pragmatism can be found in Kants doctrine of the primary of practical over pure reason, and continued to play an influential role in the theory of meaning and of truth.

In case of fact, the philosophy of mind is the modern successor to behaviourism, as do the functionalism that its early advocates were Putnam (1926-) and Sellars (1912-89), and its guiding principle is that we can define mental states by a triplet of relations they have on other mental stares, what effects they have on behaviour. The definition need not take the form of a simple analysis, but if w could write down the totality of axioms, or postdate, or platitudes that govern our theories about what things of other mental states, and our theories about what things are apt to cause (for example), a belief state, what effects it would have on a variety of other mental states, and what affects it is likely to have on behaviour, then we would have done all that is needed to make the state a proper theoretical notion. It could be implicitly defied by these theses. Functionalism is often compared with descriptions of a computer, since according to mental descriptions correspond to a description of a machine in terms of software, that remains silent about the underlaying hardware or realization of the program the machine is running. The principal advantage of functionalism includes its fit with the way we know of mental states both of ourselves and others, which is via their effects on behaviour and other mental states. As with behaviourism, critics charge that structurally complex items that do not bear mental states might nevertheless, imitate the functions that are cited. According to this criticism functionalism is too generous and would count too many things as having minds. It is also queried whether functionalism is too paradoxical, able to see mental similarities only when there is causal similarity, when our actual practices of interpretations enable us to ascribe thoughts and desires to differently from our own, it may then seem as though beliefs and desires can be variably realized causal architecture, just as much as they can be in different neurophysiological states.

The philosophical movement of Pragmatism had a major impact on American culture from the late 19th century to the present. Pragmatism calls for ideas and theories to be tested in practice, by assessing whether acting upon the idea or theory produces desirable or undesirable results. According to pragmatists, all claims about truth, knowledge, morality, and politics must be tested in this way. Pragmatism has been critical of traditional Western philosophy, especially the notions that there are absolute truths and absolute values. Although pragmatism was popular for a time in France, England, and Italy, most observers believe that it encapsulates an American faith in know-how and practicality and an equally American distrust of abstract theories and ideologies.

In mentioning the American psychologist and philosopher we find William James, who helped to popularize the philosophy of pragmatism with his book Pragmatism: A New Name for Old Ways of Thinking (1907). Influenced by a theory of meaning and verification developed for scientific hypotheses by American philosopher C. S. Peirce, James held that truths are what works, or has good experimental results. In a related theory, James argued the existence of God is partly verifiable because many people derive benefits from believing.

The Association for International Conciliation first published a William James pacifist statement, The Moral Equivalent of War, in 1910. James, a highly respected philosopher and psychologist, was one of the founders of pragmatism - a philosophical movement holding that ideas and theories must be tested in practice to assess their worth. James hoped to find a way to convince men with a long-standing history of pride and glory in war to evolve beyond the need for bloodshed and to develop other avenues for conflict resolution. Spelling and grammars represent standards of the time.

Pragmatists regard all theories and institutions as tentative hypotheses and solutions. For this reason they believed that efforts to improve society, through such means as education or politics, must be geared toward problem solving and must be ongoing. Through their emphasis on connecting theory to practice, pragmatist thinkers attempted to transform all areas of philosophy, from metaphysics to ethics and political philosophy.

Pragmatism sought a middle ground between traditional ideas about the nature of reality and radical theories of nihilism and irrationalism, which had become popular in Europe in the late 19th century. Traditional metaphysics assumed that the world has a fixed, intelligible structure and that human beings can know absolute or objective truths about the world and about what constitutes moral behavior. Nihilism and irrationalism, on the other hand, denied those very assumptions and their certitude. Pragmatists today still try to steer a middle course between contemporary offshoots of these two extremes.

The ideas of the pragmatists were considered revolutionary when they first appeared. To some critics, pragmatisms refusal to affirm any absolutes carried negative implications for society. For example, pragmatists do not believe that a single absolute idea of goodness or justice exists, but rather than these concepts are changeable and depend on the context in which they are being discussed. The absence of these absolutes, critics feared, could result in a decline in moral standards. The pragmatist’s denial of absolutes, moreover, challenged the foundations of religion, government, and schools of thought. As a result, pragmatism influenced developments in psychology, sociology, education, semiotics (the study of signs and symbols), and scientific method, as well as philosophy, cultural criticism, and social reform movements. Various political groups have also drawn on the assumptions of pragmatism, from the progressive movements of the early 20th century to later experiments in social reform.

Pragmatism is best understood in its historical and cultural context. It arose during the late 19th century, a period of rapid scientific advancement typified by the theories of British biologist Charles Darwin, whose theories suggested too many thinkers that humanity and society are in a perpetual state of progress. During this same period a decline in traditional religious beliefs and values accompanied the industrialization and material progress of the time. In consequence it became necessary to rethink fundamental ideas about values, religion, science, community, and individuality.

The three most important pragmatists are American philosophers’ Charles Sanders Peirce, William James, and John Dewey. Peirce was primarily interested in scientific method and mathematics; his objective was to infuse scientific thinking into philosophy and society, and he believed that human comprehension of reality was becoming ever greater and that human communities were becoming increasingly progressive. Peirce developed pragmatism as a theory of meaning - in particular, the meaning of concepts used in science. The meaning of the concept brittle, for example, is given by the observed consequences or properties that objects called brittle exhibit. For Peirce, the only rational way to increase knowledge was to form mental habits that would test ideas through observation, experimentation, or what he called inquiry. Many philosophers known as logical positivist, a group of philosophers who have been influenced by Peirce, believed that our evolving species was fated to get ever closer to Truth. Logical positivist emphasize the importance of scientific verification, rejecting the assertion of positivism that personal experience is the basis of true knowledge.

James moved pragmatism in directions that Peirce strongly disliked. He generalized Peirces doctrines to encompass all concepts, beliefs, and actions; he also applied pragmatist ideas to truth as well as to meaning. James was primarily interested in showing how systems of morality, religion, and faith could be defended in a scientific civilization. He argued that sentiment, as well as logic, is crucial to rationality and that the great issues of life - morality and religious belief, for example - are leaps of faith. As such, they depend upon what he called the will to believe and not merely on scientific evidence, which can never tell us what to do or what is worthwhile. Critics charged James with relativism (the belief that values depend on specific situations) and with crass expediency for proposing that if an idea or action works the way one intends, it must be right. But James can more accurately be described as a pluralist - someone who believes the world to be far too complex for any-one philosophy to explain everything.

Deweys philosophy can be described as a version of philosophical naturalism, which regards human experience, intelligence, and communities as ever-evolving mechanisms. Using their experience and intelligence, Dewey believed, human beings can solve problems, including social problems, through inquiry. For Dewey, naturalism led to the idea of a democratic society that allows all members to acquire social intelligence and progress both as individuals and as communities. Dewey held that traditional ideas about knowledge, truth, and values, in which absolutes are assumed, are incompatible with a broadly Darwinian world-view in which individuals and society is progressing. In consequence, he felt that these traditional ideas must be discarded or revised. Indeed, for pragmatists, everything people know and do depend on a historical context and are thus tentative rather than absolute.

Many followers and critics of Dewey believe he advocated elitism and social engineering in his philosophical stance. Others think of him as a kind of romantic humanist. Both tendencies are evident in Deweys writings, although he aspired to synthesize the two realms.

The pragmatist’s tradition was revitalized in the 1980s by American philosopher Richard Rorty, who has faced similar charges of elitism for his belief in the relativism of values and his emphasis on the role of the individual in attaining knowledge. Interest has renewed in the classic pragmatists - Pierce, James, and Dewey - have an alternative to Rortys interpretation of the tradition.

The Philosophy of Mind, is the branch of philosophy that considers mental phenomena such as sensation, perception, thought, belief, desire, intention, memory, emotion, imagination, and purposeful action. These phenomena, which can be broadly grouped as thoughts and experiences, are features of human beings; many of them are also found in other animals. Philosophers are interested in the nature of each of these phenomena as well as their relationships to one-another and to physical phenomena, such as motion.

The most famous exponent of dualism was the French philosopher René Descartes, who maintained that body and mind are radically different entities and that they are the only fundamental substances in the universe. Dualism, however, does not show how these basic entities are connected.

In the work of the German philosopher Gottfried Wilhelm Leibniz, the universe is held to consist of infinite measures that are numerically distinct substances, or monad. This view is pluralistic in the sense that it proposes the existence of many separate entities, and it is monistic in its assertion that each monad reflects within itself the entire universe.

Other philosophers have held that knowledge of reality is not derived from a priori principles, but is obtained only from experience. This type of metaphysic is called empiricism. Still another school of philosophy has maintained that, although an ultimate reality does exist, it is altogether inaccessible to human knowledge, which is necessarily subjective because it is confined to states of mind. Knowledge is therefore not a representation of external reality, but merely a reflection of human perceptions. This view is known as skepticism or agnosticism in respect to the soul and the reality of God.

The 18th-century German philosopher Immanuel Kant had published his monumental completion of his works as, The Critique of Pure Reason in 1781, yet three years later, he expanded on his study of the modes of thinking with an essay entitled. What is Enlightenment? In this 1784 essay, Kant challenged readers to dare to know, arguing that it was not only a civic but also a moral duty to exercise the fundamental freedoms of thought and expression.

Several major viewpoints were combined in the work of Kant, who developed a distinctive critical philosophy called transcendentalism. His philosophy is agnostic in that it denies the possibility of a strict knowledge of ultimate reality; it is empirical in that it affirms that all knowledge arises from experience and is true of objects of actual and possible experience; and it is rationalistic in that it maintains the a priori character of the structural principles of this empirical knowledge.

These principles are held to be necessary and universal in their application to experience, for in Kants view the mind furnishes the archetypal forms and categories (space, time, causality, substance, and relation) to its sensations, and these categories are logically anterior to experience, although manifested only in experience. Their logical anteriority to experience along with consciousness for which is the central focus of the philosophy of mind, least of mention, these categories or structural principle’s transcendental, that in some sense the objects have their ordinary properties, as owning their causal powers, and their spatial and temporal position, only because our minds are so structured that these are the categories we impose upon the manifold of experience. However, post-Structuralists writings to denote an external, objective languages whose independent references are of those that fixes reference meanings. These points, it is alleged cannot play any role in the interpretation of texts, their introduction only provides yet more text. So, that, in Kant, one that proves conclusion by showing that unless it was true, experiences itself would be impossible. And, again, in Kant’s Critique of Pure Reason, the selection through which it deals with the attempts to prove of the practical application, in that their personal assimilated categorical phenomena became a topic or question of transcendental resolution, and is not purely a matter of logic or mathematics, and also lies beyond the scope of both sense experience and of the proper use of theoretical answers to sense experience. But many other questions may, perhaps, include those raised by metaphysical problems, such as scepticism and physicalism. Philosophical attitudes to such questions range from fascination to outright denial of their existence. They transcend all experience, both actual and possible. Although these principles determine all experience, they do not in any way affect the nature of things in themselves. The knowledge of which these principles are the necessary conditions must not be considered, therefore, as constituting a revelation of things as they are in themselves. This knowledge concerns things only insofar as they appear to human perception or as they can be apprehended by the senses. The argument by which Kant sought to fix the limits of human knowledge within the framework of experience and to demonstrate the inability of the human mind to penetrate beyond experience strictly by knowledge to the realm of ultimate reality constitutes the critical feature of his philosophy, giving the key word to the titles of his three leading treatises, Critique of Pure Reason, Critique of Practical Reason, and Critique of Judgment. In the system propounded in these works, Kant sought also to reconcile science and religion in a world of two levels, comprising noumena, objects conceived by reason although not perceived by the senses, and phenomena, things as they appear to the senses and are accessible to material study. He maintained that, because God, freedom, and human immortality are noumenal realities, these concepts are understood through moral faith rather than through scientific knowledge. With the continuous development of science, the expansion of metaphysics to include scientific knowledge and methods became one of the major objectives of metaphysicians.

Some of Kants most distinguished followers, notably Johann Gottlieb Fichte, Friedrich Schelling, Georg Wilhelm Friedrich Hegel, and Friedrich Schleiermacher, negated Kants criticism in their elaborations of his transcendental metaphysics by denying the Kantian conception of the thing-in-itself. They thus developed an absolute idealism in opposition to Kants critical transcendentalism.

Since the formation of the hypothesis of absolute idealism, the development of metaphysics has resulted in as many types of metaphysical theory as existed in pre-Kantian philosophy, despite Kants contention that he had fixed definitely the limits of philosophical speculation. Notable among these later metaphysical theories is radical empiricism, or pragmatism, a native American form of metaphysics expounded by Charles Sanders Peirce, developed by William James, and adapted as instrumentalism by John Dewey; voluntarism, the foremost exponents of which are the German philosopher Arthur Schopenhauer and the American philosopher Josiah Royce; phenomenalism, as it is exemplified in the writings of the French philosopher Auguste Comte and the British philosopher Herbert Spencer; emergent evolution, or creative evolution, originated by the French philosopher Henri Bergson; and the philosophy of the organism, elaborated by the British mathematician and philosopher Alfred North Whitehead. The salient doctrines of pragmatism are that the chief function of thought is to guide action, that the meaning of concepts is to be sought in their practical applications, and that truth should be tested by the practical effects of belief; according to instrumentalism, ideas are instruments of action, and their truth is determined by their role in human experience. In the theory of voluntarism is of the desire to act in a particular way or have a particular thing, as to be inclined to whichever inclinations has in mind to think it fit when one’s will and judgements come in conflict, such that the aspects of mind involved in choosing or deciding upon the disposition of controlling one’s actions, impulses or emotions as a self-indulgent character. That postulated as the supreme manifestation of reality, that the exponents of phenomenalism, who are sometimes called positivist, contend that everything can be analyzed in terms of actual or possible occurrences, or phenomena, in that anything that cannot be analyzed in this manner cannot be understood in the emergence of the creative evolution, the evolutionary process is characterized as spontaneous and unpredictable rather than mechanistically determined. The philosophy of the organism combines an evolutionary stress on constant process with a metaphysical theory of God, the eternal objects, and creativity.

In the 20th century the validity of metaphysical thinking has been disputed by the logical positivist and by the so-called dialectical materialism of the Marxists. The basic principle maintained by the logical positivist is the verifiability theory of meaning. According to this theory a sentence has factual meaning only if it meets the test of observation. Logical positivist argue that metaphysical expressions such as Nothing exists except material particles and Everything is part of one all-encompassing spirit cannot be tested empirically. Therefore, according to the verifiability theory of meaning, these expressions have no factual cognitive meaning, although they can have an emotive meaning relevant to human hopes and feelings.

The dialectical materialists assert that the mind is conditioned by and reflects material reality. Therefore, speculations that conceive of constructs of the mind as having any other than material reality are themselves unreal and can result only in delusion. To these assertions metaphysicians reply by denying the adequacy of the verifiability theory of meaning and of material perception as the standard of reality. Both logical positivism and dialectical materialism, they argue, conceal metaphysical assumptions, for example, that everything is observable or at least connected with something observable and that the mind has no distinctive life of its own. In the philosophical movement known as existentialism, thinkers have contended that the questions of the nature of being and of the individuals relationships to it are extremely important and meaningful in terms of human life. The investigation of these questions is therefore considered valid whether its results can be verified objectively.

Since the 1950s the problems of systematic analytical metaphysics have been studied in Britain by Stuart Newton Hampshire and Peter Frederick Strawson, the former concerned, in the manner of Spinoza, with the relationship between thought and action, and the latter, in the manner of Kant, with describing the major categories of experience as they are embedded in language. Metaphysic has been pursued much in the spirit of positivism by Wilfred Stalker Sellars and Willard Van Orman Quine. Sellars have sought to express metaphysical questions in linguistic terms, and Quine has attempted to determine whether the structure of language commits the philosopher to asserting the existence of any entities whatever and, if so, what kind. In these new formulations the issues of metaphysics and ontology remain vital.

In the 17th century, French philosopher René Descartes proposed that only two substances ultimately exist of mind and body. Yet, if the two are entirely distinct, as Descartes believed, how can one substance interact with the other? And how, for example, is the intention of a human mind able to cause movement in the persons limbs? to have an intention to be in a state of mind that is favourably directed towards bringing about (for maintaining, or avoiding) some state of affairs, but which is not a mere desire or wish, since it also sees the subject on a course to bring that state of affairs about. The notion thus inherits its all to the problems of intentionality. The specific problems it raises include characterizing the difference between doing something accidentally and doing lies in a preceding act of mind or volition is not very happy, since it may be our automatic to do what is nevertheless intentional, for example putting one’s foot forward while walking. Conversely, unless the formation of volition is unintentional, and thus raises the same question, the presence of volition might be unintentional or beyond one’s control. Intentions are most finely grained than movements on a set of movements ,may both be answering the question and starting a wait, yet this may be intentional and the other not.

The issue of the interaction between mind and body is known in philosophy as the mind-body problem. Many fields other than philosophy shares an interest in the nature of mind. In religion, the nature of mind is connected with various conceptions of the soul and the possibility of life after death. In many abstract theories of mind there is considerable overlap between philosophy and the science of psychology. Once part of philosophy, psychology split off and formed a separate branch of knowledge in the 19th century. While psychology used scientific experiments to study mental states and events, philosophy used justifiable explanations atop of arguments and thought experiments in seeking to understand the concepts that underlie mental phenomena. Also influenced by philosophy of mind is the field of artificial intelligence (AI), which endeavors to develop computers that can mimic what the human mind can do. Cognitive science attempts to integrate the understanding of mind provided by philosophy, psychology, AI, and other disciplines. Finally, all of these fields benefit from the detailed understanding of the brain that has emerged through neuroscience in the late 20th century.

Philosophers use the characteristics of inward accessibility, subjectivity, intentionality, goal-directedness, creativity and freedom, and consciousness to distinguish mental phenomena from physical phenomena.

Perhaps the most important characteristic of mental phenomena is that they are inwardly accessible, or available to us through introspection. We each know our own minds - our sensations, thoughts, memories, desires, and fantasies - in a direct sense, by internal reflection. We also know our mental states and mental events in a way that no one else can. In other words, we have privileged access to our own mental states.

Certain mental phenomena, those we generally call experiences, have a subjective nature - that is, they have certain characteristics we become aware of when we reflect. For instance, there is something it is like to feel pain, or have an itch, or see something red. These characteristics are subjective in that they are accessible to the subject of the experience, the person who has the experience, but not to others.

Other mental phenomena, which we broadly refer to as thoughts, have a characteristic philosophers call intentionality. Intentional thoughts are about other thoughts or objects, which are represented as having certain properties or for being related to one another in a certain way. The belief that California is west of Nevada, for example, is about California and Nevada and represents the former for being west of the latter. Although we have privileged access to our intentional states, many of them do not seem to have a subjective nature, at least not in the way that experiences do.

A number of mental phenomena appear to be connected to one another as elements in an intelligent, goal-directed system. The system works as follows: First, our sense organs are stimulated by events in our environment; next, by virtue of these stimulations, we perceive things about the external world; finally, we use this information, as well as information we have remembered or inferred, to guide our actions in ways that further our goals. Goal-directedness seems to accompany only mental phenomena.

Another important characteristic of mind, especially of human minds, is the capacity for choice and imagination. Rather than automatically converting past influences into future actions, individual minds are capable of exhibiting creativity and freedom. For instance, we can imagine things we have not experienced and can act in ways that no one expects or could predict.

Mental phenomena are conscious, and consciousness may be the closest term we have for describing what is special about mental phenomena. Minds are sometimes referred to as consciousness, yet it is difficult to describe exactly what consciousness is. Although consciousness is closely related to inward accessibility and subjectivity, these very characteristics seem to hinder us in reaching an objective scientific understanding of it.

Although philosophers have written about mental phenomena since ancient times, the philosophy of mind did not garner much attention until the work of French philosopher René Descartes in the 17th century. Descartes work represented a turning point in thinking about mind by making a strong distinction between bodies and minds, or the physical and the mental. This duality between mind and body, known as Cartesian dualism, has posed significant problems for philosophy ever since.

Descartes believed there are two basic kinds of things in the world, a belief known as substance dualism. For Descartes, the principles of existence for these two groups of things - bodies and minds - are completely different from one another: Bodies exist by being extended in space, while minds exist by being conscious. According to Descartes, nothing can be done to give a body thought and consciousness. No matter how we shape a body or combine it with other bodies, we cannot turn the body into a mind, a thing that is conscious, because being conscious is not a way of being extended.

For Descartes, a person consists of a human body and a human mind causally interacting with one another. For example, the intentions of a human being of a quality or by some degree actionable above which point, may well have been responsible for bringing about that persons’ limbs to move. In this way, the mind can affect the body. In addition, the sense organs of a human being maybe affected by light, pressure, or sound, external sources, which in turn affect the brain, affecting mental states. Thus, the body may affect the mind. Exactly how mind can affect body, and vice versa, is a central issue in the philosophy of mind, and is known as the mind-body problem. According to Descartes, this interaction of mind and body is peculiarly intimate. Unlike the interaction between a pilot and his ship, the connection between mind and body more closely resembles two substances that have been thoroughly mixed together.

In response to the mind-body problem arising from Descartes theory of substance dualism, a number of philosophers have advocated various forms of substance monism, the doctrine that there is ultimately just one kind of thing in reality. In the 18th century, Irish philosopher George Berkeley claimed there were no material objects in the world, only minds and their ideas. Berkeley thought that talk about physical objects was simply a way of organizing the flow of experience. Near the turn of the 20th century, American psychologist and philosopher William James proposed another form of substance monism. James claimed that experience is the basic stuff from which both bodies and minds are constructed.

Most philosophers of mind today are substance monists of a third type: They are materialists who believe that everything in the world is basically material, or a physical object. Among materialists, there is still considerable disagreement about the status of mental properties, which are conceived as properties of bodies or brains. Materialists who are property diarists believe that mental properties are an additional kind of property or attribute, not reducible to physical properties. Property dualists have the problem of explaining how such properties can fit into the world envisaged by modern physical science, according to which there are physical explanations for all things.

Materialists who are property monists believe that there is ultimately only one type of property, although they disagree on whether or not mental properties exist in material form. Some property monists, known as reductive materialists, hold that mental properties exist simply as a subset of relatively complex and nonbasic physical properties of the brain. Reductive materialists have the problem of explaining how the physical states of the brain can be inwardly accessible and have a subjective character, as mental states do. Other property monists, known as eliminative materialists, consider the whole category of mental properties to be a mistake. According to them, mental properties should be treated as discredited postulates of an outmoded theory. Eliminative materialism is difficult for most people to accept, since we seem to have direct knowledge of our own mental phenomena by introspection and because we use the general principles we understand about mental phenomena to predict and explain the behavior of others.

Philosophy of mind concerns itself with a number of specialized problems. In addition to the mind-body problem, important issues include those of the individuals’ identity, immortality, and artificial intelligence.

During much of Western history, the mind has been identified with the soul as presented in Christian Theology. According to Christianity, the soul is the source of a persons’ identity and is usually regarded as immaterial; thus, it is capable of enduring after the death of the body. Descartes conception of the mind as a separate, nonmaterial substance fits well with this understanding of the soul. In Descartes view, we are aware of our bodies only as the cause of sensations and other mental phenomena. Consequently our personal essence is composed more fundamentally of mind and the preservation of the mind after death would constitute our continued existence.

The mind as conceivable to envisage the possibilities by materialist forms of substance, just as monism does not fit as neatly with this traditional concept of the soul. With materialism, once a physical body is destroyed, nothing enduring remains. Some philosophers think that a concept of personal identity can be constructed that permits the possibility of life after death without appealing to separate immaterial substances. Following in the tradition of 17th-century British philosopher John Locke, these philosophers propose that a person consists of a stream of mental events linked by memory. These links of memory, rather than a single underlying substance, provide the unity of a single consciousness through time. Immortality is conceivable if we think of these memory links as connecting a later consciousness in heaven with an earlier one on earth.

The field of artificial intelligence also raises interesting questions for the philosophy of mind. People have designed machines that mimic or model many aspects of human intelligence, and there are robots currently in use whose behavior is described in terms of goals, beliefs, and perceptions. Such machines are capable of behavior that, were it exhibited by a human being, would surely be taken to be free and creative. As an example, in 1996 an IBM computer named Deep Blue won a chess game against Russian world champion Garry Kasparov under international match regulations. Moreover, it is possible to design robots that have some sort of privileged access to their internal states. Philosophers disagree over whether such robots truly think or simply appear to think and whether such robots should be considered to be conscious

Dualism, in philosophy, the theory that the universe is explicable only as a whole composed of two distinct and mutually irreducible elements. In Platonic philosophy the ultimate dualism is between being and nonbeing - that is, between ideas and matter. In the 17th century, dualism took the form of belief in two fundamental substances: mind and matter. French philosopher René Descartes, whose interpretation of the universe exemplifies this belief, was the first to emphasize the irreconcilable difference between thinking substance (mind) and extended substance (matter). The difficulty created by this view was to explain how mind and matter interact, as they apparently do in human experience. This perplexity caused some Cartesians to deny entirely any interaction between the two. They asserted that mind and matter are inherently incapable of affecting each other, and that any reciprocal action between the two is caused by God, who, on the occasion of a change in one, produces a corresponding change in the other. Other followers of Descartes abandoned dualism in favor of monism.

In the 20th century, reaction against the monistic aspects of the philosophy of idealism has to some degree revived dualism. One of the most interesting defenses of dualism is that of Anglo-American psychologist William McDougall, who divided the universe into spirit and matter and maintained that good evidence, both psychological and biological, indicates the spiritual basis of physiological processes. French philosopher Henri Bergson in his great philosophic work Matter and Memory likewise took a dualistic position, defining matter as what we perceive with our senses and possessing in itself the qualities that we perceive in it, such as color and resistance. Mind, on the other hand, reveals itself as memory, the faculty of storing up the past and utilizing it for modifying our present actions, which otherwise would be merely mechanical. In his later writings, however, Bergson abandoned dualism and came to regard matter as an arrested manifestation of the same vital impulse that composes life and mind.

Dualism, in philosophy, the theory that the universe is explicable only as a whole composed of two distinct and mutually irreducible elements. In Platonic philosophy the ultimate dualism is between being and nonbeing - that is, between ideas and matter. In the 17th century, dualism took the form of belief in two fundamental substances: mind and matter. French philosopher René Descartes, whose interpretation of the universe exemplifies this belief, was the first to emphasize the irreconcilable difference between thinking substance (mind) and extended substance (matter). The difficulty created by this view was to explain how mind and matter interact, as they apparently do in human experience. This perplexity caused some Cartesians to deny entirely any interaction between the two. They asserted that mind and matter are inherently incapable of affecting each other, and that any reciprocal action between the two is caused by God, who, on the occasion of a change in one, produces a corresponding change in the other. Other followers of Descartes abandoned dualism in favor of monism.

In the 20th century, reaction against the monistic aspects of the philosophy of idealism has to some degree revived dualism. One of the most interesting defenses of dualism is that of Anglo-American psychologist William McDougall, who divided the universe into spirit and matter and maintained that good evidence, both psychological and biological, indicates the spiritual basis of physiological processes. French philosopher Henri Bergson in his great philosophic work Matter and Memory likewise took a dualistic position, defining matter as what we perceive with our senses and possessing in itself the qualities that we perceive in it, such as color and resistance. Mind, on the other hand, reveals itself as memory, the faculty of storing up the past and utilizing it for modifying our present actions, which otherwise would be merely mechanical. In his later writings, however, Bergson abandoned dualism and came to regard matter as an arrested manifestation of the same vital impulse that composes life and mind.

For many people understanding the place of mind in nature is the greatest philosophical problem. Mind is often though to be the last domain that stubbornly resists scientific understanding and philosophers defer over whether they find that cause for celebration or scandal. The mind-body problem in the modern era was given its definitive shape by Descartes, although the dualism that he espoused is in some form whatever there is a religious or philosophical tradition there is a religious or philosophical tradition whereby the soul may have an existence apart from the body. While most modern philosophers of mind would reject the imaginings that lead us to think that this makes sense, there is no consensus over the best way to integrate our understanding of people as bearers of physical properties lives on the other.

Occasionalism finds from it terms as employed to designate the philosophical system devised by the followers of the 17th-century French philosopher René Descartes, who, in attempting to explain the interrelationship between mind and body, concluded that God is the only cause. The occasionalists began with the assumption that certain actions or modifications of the body are preceded, accompanied, or followed by changes in the mind. This assumed relationship presents no difficulty to the popular conception of mind and body, according to which each entity is supposed to act directly on the other; these philosophers, however, asserting that cause and effect must be similar, could not conceive the possibility of any direct mutual interaction between substances as dissimilar as mind and body.

According to the occasionalists, the action of the mind is not, and cannot be, the cause of the corresponding action of the body. Whenever any action of the mind takes place, God directly produces in connection with that action, and by reason of it, a corresponding action of the body; the converse process is likewise true. This theory did not solve the problem, for if the mind cannot act on the body (matter), then God, conceived as mind, cannot act on matter. Conversely, if God is conceived as other than mind, then he cannot act on mind. A proposed solution to this problem was furnished by exponents of radical empiricism such as the American philosopher and psychologist William James. This theory disposed of the dualism of the occasionalists by denying the fundamental difference between mind and matter.

Generally, along with consciousness, that experience of an external world or similar scream or other possessions, takes upon itself the visual experience or to prevent one from possessing of some normal visual experience, that this, however, does not perceive the world accurately. In its frontal experiment. As researchers reared kittens in total darkness, except that for five hours a day the kittens were placed in an environment with only vertical lines. When the animals were later exposed to horizontal lines and forms, they had trouble perceiving these forms.

Philosophers have long debated the role of experience in human perception. In the late 17th century, Irish philosopher William Molyneux wrote to his friend, English philosopher John Locke, and asked he to consider the following scenario: Suppose that you could restore sight to a person who was blind. Using only vision, would that person be able to tell the difference between a cube and a sphere, which she or he had previously experienced only through touch? Locke, who emphasized the role of experience in perception, thought the answer was no. Modern science actually allows us to address this philosophical question, because a very small number of people who were blind have had their vision restored with the aid of medical technology.

Two researchers, British psychologist Richard Gregory and British-born neurologists’ Oliver Sacks, have written about their experiences with men who were blind for a long time due to cataracts and then had their vision restored late in life. When their vision was restored, they were often confused by visual input and were unable to see the world accurately. For instance, they could detect motion and perceive colors, but they had great difficulty with complex stimuli, such as faces. Much of their poor perceptual ability was probably due to the fact that the synapses in the visual areas of their brains had received little or no stimulation throughout their lives. Thus, without visual experience, the visual system does not develop properly.

Visual experience is useful because it creates memories of past stimuli that can later serve as a context for perceiving new stimuli. Thus, you can think of experience as a form of context that you carry around with you. A visual illusion occurs when your perceptual experience of a stimulus is substantially different from the actual stimulus you are viewing. In the previous example, you saw the green circles as different sizes, even though they were actually the same size. To experience another illusion, look at the illustration entitled Zöllner Illusion. What shape do you see? You may see a trapezoid that is wider at the top, but the actual shape is a square. Such illusions are natural artifacts of the way our visual systems work. As a result, illusions provide important insights into the functioning of the visual system. In addition, visual illusions are fun to experience.

Consider the pair of illusions in the accompanying illustration, Illusions of Length. These illusions are called geometrical illusions, because they use simple geometrical relationships to produce the illusory effects. The first illusion, the Müller-Lyer illusion, is one of the most famous illusions in psychology. Which of the two horizontal lines is longer? Although your visual system tells you that the lines are not equal, a ruler would tell you that they are equal. The second illusion is called the Ponzo illusion. Once again, the two lines do not appear to be equal in length, but they are.

Prevailing states of consciousness, are not as simple, or agreed-upon by any steadfast and held definition of itself, in so, that, consciousness exists. Attempted definitions tend to be tautological (for example, consciousness defined s awareness) or merely descriptive (for example, consciousness described as sensations, thoughts, or feelings). Despite this problem of definition, the subject of consciousness has had a remarkable history. At one time the primary subject matter of psychology, consciousness as an area of study suffered an almost total demise, later reemerging to become a topic of current interest.

René Descartes applied rigorous scientific methods of deduction to his exploration of philosophical questions. Descartes is probably best known for his pioneering work in philosophical skepticism. Author Tom Sorell examines the concepts behind Descartes work Meditationes de Prima Philosophia (1641; Meditations on First Philosophy), focusing on its unconventional use of logic and the reactions it aroused. Most of the philosophical discussions of consciousness arose from the mind-body issues posed by the French philosopher and mathematician René Descartes in the 17th century. Descartes asked: Is the mind, or consciousness, independent of matter? Is consciousness extended (physical) or unextended (nonphysical)? Is consciousness determinative, or is it determined? English philosophers such as John Locke equated consciousness with physical sensations and the information they provide, whereas European philosophers such as Gottfried Wilhelm Leibniz and Immanuel Kant gave a more central and active role to consciousness.

The philosopher who most directly influenced subsequent exploration of the subject of consciousness was the 19th-century German educator Johann Friedrich Herbart, who wrote that ideas had quality and intensity and that they may inhibit or facilitate one another. Thus, ideas may pass from states of reality (consciousness) to states of a tendency (unconsciousness), with the dividing line between the two states being described as the threshold of consciousness. This formulation of Herbart clearly presages the development, by the German psychologist and physiologist Gustav Theodor Fechner, of the psychophysical measurement of sensation thresholds, and the later development by Sigmund Freud of the concept of the unconscious.

The experimental analysis of consciousness dates from 1879, when the German psychologist Wilhelm Max Wundt started his research laboratory. For Wundt, the task of psychology was the study of the structure of consciousness, which extended well beyond sensations and included feelings, images, memory, attention, duration, and movement. Because early interest focused on the content and dynamics of consciousness, it is not surprising that the central methodology of such studies was introspection; that is, subjects reported on the mental contents of their own consciousness. This introspective approach was developed most fully by the American psychologist Edward Bradford Titchener at Cornell University. Setting his task as that of describing the structure of the mind, Titchener attempted to detail, from introspective self-reports, the dimensions of the elements of consciousness. For example, taste was dimensionalized into four basic categories: sweet, sour, salt, and bitter. This approach was known as structuralism.

By the 1920s, however, a remarkable revolution had occurred in psychology that was to essentially remove considerations of consciousness from psychological research for some 50 years: Behaviorism captured the field of psychology. The main initiator of this movement was the American psychologist John Broadus Watson. In a 1913 article, Watson stated, I believe that we can write a psychology and never use the term’s consciousness, mental states, mind . . . imagery and the like. Psychologists then turned almost exclusively to behavior, as described in terms of stimulus and response, and consciousness was totally bypassed as a subject. A survey of eight leading introductory psychology texts published between 1930 and the 1950s found no mention of the topic of consciousness in five texts, and in two it was treated as a historical curiosity.

Occasioning, in the late 1950s, were of interest in the subject of consciousness returned, specifically in those subjects and techniques relating to altered states of consciousness: sleep and dreams, meditation, biofeedback, hypnosis, and drug-induced states. Much into a surge of sleep and dream research was directly fueled by a discovery relevant to the nature of consciousness. A physiological indicator of the dream state was found: At roughly 90-minute intervals, the eyes of sleepers were observed to move rapidly, and at the same time the sleepers brain waves would show a pattern resembling the waking state. When people were awakened during these periods of rapid eye movement, they almost always reported dreams, whereas if awakened at other times they did not. This and other research clearly indicated that sleep, once considered a passive state, were instead an active state of consciousness.

During the 1960s, an increased search for higher levels of consciousness through meditation resulted in a growing interest in the practices of Zen Buddhism and Yoga from Eastern cultures. A full flowering of this movement in the United States was seen in the development of training programs, such as Transcendental Meditation, that were self-directed procedures of physical relaxation and focused attention. Biofeedback techniques also were developed to bring body systems involving factors such as blood pressure or temperature under voluntary control by providing feedback from the body, so that subjects could learn to control their responses. For example, researchers found that persons could control their brain-wave patterns to some extent, particularly the so-called alpha rhythms generally associated with a relaxed, meditative state. This finding was especially relevant to those interested in consciousness and meditation, and a number of alpha training programs emerged.

Another subject that led to increased interest in altered states of consciousness was hypnosis, which involves a transfer of conscious control from the subject to another person. Hypnotism has had a long and intricate history in medicine and folklore and has been intensively studied by psychologists. Much has become known about the hypnotic state, relative to individual suggestibility and personality traits; the subject has now largely been demythologized, and the limitations of the hypnotic state are fairly well known. Despite the increasing use of hypnosis, however, much remains to be learned about this unusual state of focused attention.

Finally, many people in the 1960s experimented with the psychoactive drugs known as hallucinogens, which produce ill-exaggerations of consciousness. The most prominent of these drugs are lysergic acid diethylamide, or LSD; mescaline, and psilocybin; the latter two have long been associated with religious ceremonies in various cultures. LSD, because of its radical thought-modifying properties, was initially explored for its so-called mind-expanding potential and for its psychotomimetic effects (imitating psychoses). Little positive use, however, has been found for these drugs, and their use is highly restricted.

As the concept of a direct, simple linkage between environment and behavior became unsatisfactory in recent decades, the interest in altered states of consciousness may be taken as a visible sign of renewed interest in the topic of consciousness. That persons are active and intervening participants in their behavior has become increasingly clear. Environments, rewards, and punishments are not simply defined by their physical character. Memories are organized, not simply stored. An entirely new area called cognitive psychologies have emerged that centers on these concerns. In the study of children, increased attention is being paid to how they understand, or perceive, the world at different ages. In the field of animal behavior, researchers increasingly emphasize the inherent characteristics resulting from the way a species has been shaped to respond adaptively to the environment. Humanistic psychologists, with a concern for self-actualization and growth, have emerged after a long period of silence. Throughout the development of clinical and industrial psychology, the conscious states of persons in terms of their current feelings and thoughts were of obvious importance. The role of consciousness, however, was often deemphasized in favor of unconscious needs and motivations. Trends can be seen, however, toward a new emphasis on the nature of states of consciousness.

Perception (psychology), spreads of a process by which organisms interpret and organize sensation to produce a meaningful experience of the world. Sensation usually refers to the immediate, relatively unprocessed result of stimulation of sensory receptors in the eyes, ears, nose, tongue, or skin. Perception, on the other hand, better describes ones ultimate experience of the world and typically involves further processing of sensory input. In practice, sensation and perception are virtually impossible to separate, because they are part of one continuous process.

Our sense organs translate physical energy from the environment into electrical impulses processed by the brain. For example, light, in the form of electromagnetic radiation, causes receptor cells in our eyes to activate and send signals to the brain. But we do not understand these signals as pure energy. The process of perception allows us to interpret them as objects, events, people, and situations.

Without the ability to organize and interpret sensations, life would seem like a meaningless jumble of colors, shapes, and sounds. A person without any perceptual ability would not be able to recognize faces, understand language, or avoid threats. Such a person would not survive for long. In fact, many species of animals have evolved exquisite sensory and perceptual systems that aid their survival.

Organizing raw sensory stimuli into meaningful experiences involves cognition, a set of mental activities that includes thinking, knowing, and remembering. Knowledge and experience are extremely important for perception, because they help us make sense of the input to our sensory systems. To understand these ideas, try to read the following passage:

You could probably read the text, but not as easily as when you read letters in their usual orientation. Knowledge and experience allowed you to understand the text. You could read the words because of your knowledge of letter shapes, and maybe you even have some prior experience in reading text upside down. Without knowledge of letter shapes, you would perceive the text as meaningless shapes, just as people who do not know Chinese or Japanese see the characters of those languages as meaningless shapes. Reading, then, is a form of visual perception.

Note that as above, whereby you did not stop to read every single letter carefully. Instead, you probably perceived whole words and phrases. You may have also used context to help you figure out what some of the words must be. For example, recognizing the upside may have helped you predict down, because the two words often occur together. For these reasons, you probably overlooked problems with the individual letters - some of them, such as the n in down, are mirror images of normal letters. You would have noticed these errors immediately if the letters were right side up, because you have much more experience seeing letters in that orientation.

How people perceive a well-organized pattern or whole, instead of many separate parts, is a topic of interest in Gestalt psychology. According to Gestalt psychologists, the whole is different from the sum of its parts. Gestalts is a German word meaning configuration or pattern.

The three founders of Gestalt psychology were German researchers’ Max Wertheimer, Kurt Koffka, and Wolfgang Köhler. These men identified a number of principles by which people organize isolated parts of a visual stimulus into groups or whole objects. There are five main laws of grouping: proximity, similarity, continuity, closure, and common fate. A sixth law, that of simplicity, encompasses all of these laws.

Although most often applied to visual perception, the Gestalt laws also apply to perception in other senses. When we listen to music, for example, we do not hear a series of disconnected or random tones. We interpret the music as a whole, relating the sounds to each other based on how similar they are in pitch, how close together they are in time, and other factors. We can perceive melodies, patterns, and form in music. When a song is transposed to another key, we still recognize it, even though all of the notes have changed.

The law of proximity states that the closer objects are to one another, the more likely we are to mentally group them together. In the illustration below, we perceive as groups the boxes that are closest to one another. Note that we do not see the second and third boxes from the left as a pair, because they are spaced farther apart.

The law of similarity leads us to link together parts of the visual field that are similar in color, lightness, texture, shape, or any other quality. That is why, in the following illustration, we perceive rows of objects instead of columns or other arrangements.

The law of continuity leads us to see a line as continuing in a particular direction, rather than making an abrupt turn. In the drawing on the left below, we see a straight line with a curved line running through it. Notice that we do not see the drawing as consisting of the two pieces in the drawing on the right.

According to the law of closure, we prefer complete forms to incomplete forms. Thus, in the drawing below, we mentally close the gaps and perceive a picture of a duck. This tendency allows us to perceive whole objects from incomplete and imperfect forms.

The law of common fate leads us to group together objects that move in the same direction. In the following illustration, imagine that three of the balls are moving in one direction, and two of the balls are moving in the opposite direction. If you saw these in actual motion, you would mentally group the balls that moved in the same direction. Because of this principle, we often see flocks of birds or schools of fish as one unit.

Central to the approach of Gestalt psychologists is the law of prägnanz, or simplicity. This general notions, which encompass all other Gestalt laws, states that people intuitively prefer the simplest, most stable of possible organizations. For example, look at the illustration below. You could perceive this in a variety of ways: as three overlapping disks; as one whole disk and two partial disks with slices cut out of their right sides; or even as a top view of three-dimensional, cylindrical objects. The law of simplicity states that you will see the illustration as three overlapping disks, because that is the simplest interpretation.

Not only does perception involve organization and grouping, it also involves distinguishing an object from its surroundings. Notice that once you perceive an object, the area around that object becomes the background. For example, when you look at your computer monitor, the wall behind it becomes the background. The object, or figure, is closer to you, and the background, or ground, is farther away.

Gestalt psychologists have devised ambiguous figure-ground relationships - that is, drawings in which the figure and ground can be reversed - to illustrate their point that the whole is different from the sum of its parts. Consider the accompanying illustration entitled Figure and Ground. You may see a white vase as the figure, in which case you will see it displayed on a dark ground. However, you may also see two dark faces that point toward one another. Notice that when you do so, the white area of the figure becomes the ground. Even though your perception may alternate between these two possible interpretations, the parts of the illustration are constant. Thus, the illustration supports the Gestalt position that the whole is not determined solely by its parts. The Dutch artist M. C. Escher was intrigued by ambiguous figure-ground relationships.

Although such illustrations may fool our visual systems, people are rarely confused about what they see. In the real world, vases do not change into faces as we look at them. Instead, our perceptions are remarkably stable. Considering that we all experience rapidly changing visual input, the stability of our perceptions is more amazing than the occasional tricks that fool our perceptual systems. How we perceive, a stable world is due, in part, to a number of factors that maintain perceptual constancy.

As we view an object, the image it projects on the retinas of our eyes changes with our viewing distance and angle, the level of ambient light, the orientation of the object, and other factors. Perceptual constancy allows us to perceive an object as roughly the same in spite of changes in the retinal image. Psychologists have identified a number of perceptual consistencies, including lightness constancy, color constancy, shape constancy, and size constancy.

Lightness constancy means that our perception of an objects lightness or darkness remains constant despite changes in illumination. To understand lightness constancy, try the following demonstration. First, take a plain white sheet of paper into a brightly lit room and note that the paper appears to be white. Then, turn out a few of the lights in the room. Note that the paper continues to appear white. Next, if it will not make the room pitch black, turn out some more lights. Note that the paper appears to be white regardless of the actual amount of light energy that enters the eye.

Lightness constancy illustrates an important perceptual principle: Perception is relative. Lightness constancy may occur because the white piece of paper reflects more light than any of the other objects in the room - regardless of the different lighting conditions. That is, you may have determined the lightness or darkness of the paper relative to the other objects in the room. Another explanation, proposed by 19th-century German physiologist Hermann von Helmholtz, is that we unconsciously take the lighting of the room into consideration when judging the lightness of objects.

Color constancy is closely related to lightness constancy. Color constancy means that we perceive the color of an object as the same despite changes in lighting conditions. You have experienced color constancy if you have ever worn a pair of sunglasses with colored lenses. In spite of the fact that the colored lenses change the color of light reaching your retina, you still perceive white objects as white and red objects as red. The explanations for color constancy parallel those for lightness constancy. One proposed explanation is that because the lenses tint everything with the same color, we unconsciously subtract that color from the scene, leaving the original colors.

Another perceptual constancy is shape constancy, which means that you perceive objects as retaining the same shape despite changes in their orientation. To understand shape constancy, hold a book in front of your face so that you are looking directly at the cover. The rectangular nature of the book should be very clear. Now, rotate the book away from you so that the bottom edge of the cover is much closer to you than the top edge. The image of the book on your retina will now be quite different. In fact, the image will now be trapezoidal, with the bottom edge of the book larger on your retina than the top edge. (Try to see the trapezoid by closing one eye and imagining the cover as a two-dimensional shape.) In spite of this trapezoidal retinal image, you will continue to see the book as rectangular. In large measure, shape constancy occurs because your visual system takes depth into consideration.

Depth perception also plays a major role in size constancy, the tendency to perceive objects as staying the same size despite changes in our distance from them. When an object is near to us, its image on the retina is large. When that same objects is far away, its image on the retina is small. In spite of the changes in the size of the retinal image, we perceive the object as the same size. For example, when you see a person at a great distance from you, you do not perceive that person as very small. Instead, you think that the person is of normal size and far away. Similarly, when we view a skyscraper from far away, its image on our retina is very small - yet we perceive the building as very large.

Psychologists have proposed several explanations for the phenomenon of size constancy. First, people learn the general size of objects through experience and use this knowledge to help judge size. For example, we know that insects are smaller than people and that people are smaller than elephants. In addition, people take distance into consideration when judging the size of an object. Thus, if two objects have the same retinal image size, the object that seems farther away will be judged as larger. Even infants seem to possess size constancy.

Another explanation for size constancy involves the relative sizes of objects. According to this explanation, we see objects as the same size at different distances because they stay the same size relative to surrounding objects. For example, as we drive toward a stop sign, the retinal image sizes of the stop sign relative to a nearby tree remain constant - both images grow larger at the same rate.

Depth perception is the ability to see the world in three dimensions and to perceive distance. Although this ability may seem simple, depth perception is remarkable when you consider that the images projected on each retina are two-dimensional. From these flat images, we construct a vivid three-dimensional world. To perceive depth, we depend on two main sources of information: binocular disparity, a depth cue that requires both eyes; and monocular cues, which allow us to perceive depth with just one eye.

An autostereogram is a remarkable kind of two-dimensional image that appears three-dimensional (3-D) when viewed in the right way. To see the 3-D image, first make sure you are viewing the expanded version of this picture. Then try to focus your eyes on a point in space behind the picture, keeping your gaze steady. An image of a person playing a piano will appear. On the account that our eyes are spaced about 7 cm. (about 3 in.) apart, the left and right retinas receive slightly different images. This difference in the left and right images is called binocular disparity. The brain integrates these two images into a single three-dimensional image, allowing us to perceive depth and distance.

For a demonstration of binocular disparity, fully extend your right arm in front of you and hold up your index finger. Now, alternate closing your right eye and then your left eye while focusing on your index finger. Notice that your finger appears to jump or shift slightly - a consequence of the two slightly different images received by each of your retinas. Next, keeping your focus on your right index finger, hold your left index finger up much closer to your eyes. You should notice that the nearer finger creates a double image, which is an indication to your perceptual system that it is at a different depth than the farther finger. When you alternately close your left and right eyes, notice that the nearer finger appears to jump much more than the more distant finger, reflecting a greater amount of binocular disparity.

You have probably experienced a number of demonstrations that use binocular disparity to provide a sense of depth. A stereoscope is a viewing device that presents each eye with a slightly different photograph of the same scene, which generates the illusion of depth. The photographs are taken from slightly different perspectives, one approximating the view from the left eye and the other representing the view from the right eye. The View-Master, a childrens toy, is a modern type of stereoscope.

Another phenomenon that makes use of binocular disparity is the autostereogram. The autostereogram is a two-dimensional image that can appear three-dimensional without the use of special glasses or a stereoscope. Several different types of autostereograms exist. The most popular, based on the single-image random point at which to point of a stereogram, seemingly becomes three-dimensional when the viewer relaxes or delouses the eyes, as if focusing on a point in space behind the image. The two-dimensional image usually consists of random dots or lines, which, when viewed properly, coalesce into a previously unseen three-dimensional image. This type of autostereogram was first popularized in the Magic Eye series of books in the early 1990s, although its invention traces back too 1979. Most autostereograms are produced using computer software. The mechanism by which autostereograms work is complex, but they employ the same principle as the stereoscope and 3-D movies. That is, each eye receives a slightly different image, which the brain fuses into a single three-dimensional image.

Although binocular disparity is a very useful depth cue, it is only effective over a fairly short range - less than three m (10 ft.). As our distance from objects increases, the binocular disparity decreases - that is, the images received by each retina become more and more similar. Therefore, for distant objects, your perceptual system cannot rely on binocular disparity as a depth cue. However, you can still determine that some objects are nearer and some farther away because of monocular cues about depth.

To portray a realistic three-dimensional world on a two-dimensional canvas, artists must make use of a variety of depth cues. It was not until the 1400s, during the Italian Renaissance, that artists began to understand linear perspective fully and to portray depth convincingly. Shown here are several paintings that produce a sense of depth.

Close one eye and look around you. Notice the richness of depth that you experience. How does this sharp sense of three-dimensional emergence from stimulant singularity toward the two-dimensional retina? The answer lies in monocular cues, or cues to depth that are effective when viewed with only one eye.

The problem of encoding depth on the two-dimensional retina is quite similar to the problem faced by an artist who wishes to realistically portray depth on a two-dimensional canvas. Some artists are amazingly adept at doing so, using a variety of monocular cues to give their works a sense of depth.

Although there are many kinds of monocular cues, the most important are interposition, atmospheric perspective, texture gradient, linear perspective, size cues, height cues, and motion parallax.

People commonly rely on interposition, or the overlap between objects, to judge distances. When one object partially obscures our view of another object, we judge the covered object as farther away from us.

Probably the most important monocular cue is interposition, or overlap. When one object overlaps or partly blocks our view of another object, we judge the covered object for being farther away from us. This depth cue is all around us - look around you and notice how many objects are partly obscured by other objects. To understand how much we rely on interposition, try this demonstration. Hold two pens, one in each hand, a short distance in front of your eyes. Hold the pens several centimeters apart so they do not overlap, but move one pen just slightly farther away from you than the other. Now close one eye. Without binocular vision, notice how difficult it is to judge which pen is more distant. Now, keeping one eye closed, move your hands closer and closer together until one pen moves in front of the other. Notice how interposition makes depth perception much easier.

When we look out over vast distances, faraway points look hazy or blurry. This effect is known as atmospheric perspective, and it helps us to judge distances. In this picture, the ridges that are farther away appear hazier and less detailed than the closer ridges.

The air contains microscopic particles of dust and moisture that make distant objects look hazy or blurry. This effect is called atmospheric perspective or aerial perspective, and we use it to judge distance. In the anthem, Oh Canada it draws reference to the effect of atmospheric perspectives, which make’s distant mountains appear bluish or purple. When you are standing on a mountain, you see brown earth, gray rocks, and green trees and grass - but little that is purple. When you are looking at a mountain from a distance, however, atmospheric particles bend the light so that the rays that reach your eyes lie in the blue or purple part of the color spectrum. This same effect makes the sky appear blue.

An influential American psychologist, James J. Gibson, was among the first people to recognize the importance of texture gradients in perceiving depth. A texture gradient arises whenever we view a surface from a slant, rather than directly from above. Most surfaces - such as the ground, a road, or a field of flowers - have a texture. The texture becomes denser and less detailed as the surface recedes into the background, and this information helps us to judge depth. For example, look at the floor or ground around you. Notice that the apparent texture of the floor changes over distance. The texture of the floor near you appears more detailed than the texture of the floor farther away. When objects are placed at different locations along a texture gradient, judging their distance from you becomes fairly easy.

Linear perspectives mean that parallel lines, such as the white lines of this road, appear to converge with greater distance and reach a vanishing point at the horizon. We use our knowledge of linear perspective to help us judge distances.

Artists have learned to make great use of linear perspective in representing a three-dimensional world on a two-dimensional canvas. Linear perspective refers to the fact that parallel lines, such as railroad tracks, appears to converge with distance, eventually reaching a vanishing point at the horizon. The more the lines converge, the farther away they appear.

When estimating an objects distance from us, we take into account the size of its image relative to other objects. This depth cue is known as relative size. In this photograph, because we assume that the airplanes are the same size, we judge the airplanes that take up less of the image for being farther away from the camera.

Another visual cue to apparent depth is closely related to size constancy. According to size constancy, even though the size of the retinal image may change as an object moves closer to us or farther from us, we perceive that object as staying about the same size. We are able to do so because we take distance into consideration. Thus, if we assume that two objects are the same size, we perceive the object that casts a smaller retinal image as farther away than the object that casts a larger retinal image. This depth cue is known as relative size, because we consider the size of an objects retinal images relative to other objects when estimating its distance.

Another depth cue involves the familiar size of objects. Through experience, we become familiar with the standard size of certain objects, such as houses, cars, airplanes, people, animals, books, and chairs. Knowing the size of these objects helps us judge our distance from them and from objects around them.

When judging an objects distance, we consider its height in our visual field relative to other objects. The closer an object is to the horizon in our visual field, the farther away we perceive it to be. For example, the wildebeest that are higher in this photograph appear farther away than those that are lower.

We perceive points nearer to the horizon as more distant than points that are farther away from the horizon. This means that below the horizon, objects higher in the visual field appear farther away than those that are lower. Above the horizon, objects lower in the visual field appear farther away than those that are higher. For example, in the accompanying picture entitled Relative Height, the animals higher in the photo appear farther away than the animals lower in the photo. But above the horizon, the clouds lower in the photo appear farther away than the clouds higher in the photo. This depth cue is called relative elevation or relative height, because when judging an objects distance, we consider its height in our visual field relative to other objects.

The monocular cues discussed so far - interposition, atmospheric perspective, texture gradient, linear perspective, size cues, and height cues - are sometimes called pictorial cues, because artists can use them to convey three-dimensional information. Another monocular cue cannot be represented on a canvas. Motion, and parallax occurs when objects at different distances from you appear to move at different rates when you are in motion. The next time you are driving along in a car, pay attention to the rate of movement of nearby and distant objects. The fence near the road appears to whiz past you, while the more distant hills or mountains appear to stay in virtually the same position as you move. The rate of an objects movement provides a cue to its distance.

Although motion plays an important role in depth perception, the perception of motion is an important phenomenon in its own right. It allows a baseball outfielder to calculate the speed and trajectory of a ball with extraordinary accuracy. Automobile drivers rely on motion perception to judge the speeds of other cars and avoid collisions. A cheetah must be able to detect and respond to the motion of antelopes, its chief prey, in order to survive.

Initially, you might think that you perceive motion when an objects image moves from one part of your retina to another part of your retina. In fact, which is what occurs if you are staring straight ahead and a person walks in front of you. Motion perception, however, is not that simple - if it were, the world would appear to move every time we moved our eyes. Keep in mind that you are almost always in motion. As you walk along a path, or simply move your head or your eyes, images from many stationary objects move around on your retina. How does your brain know which movement on the retina is due to your own motion and which is due to motion in the world? Understanding that distinction is the problem that faces psychologists who want to explain motion perception.

One explanation of motion perception involves a form of unconscious inference. That is, when we walk around or move our head in a particular way, we unconsciously expect that images of stationary objects will move on our retina. We discount such movement on the retina as due to our own bodily motion and perceive the objects as stationary.

In contrast, when we are moving and the image of an object does not move on our retina, we perceive that object as moving. Consider what happens as a person moves in front of you and you track that persons motion with your eyes. You move your head and your eyes to follow the persons’ movement, with the result that the image of the person does not move on your retina. The fact that the persons image stays in roughly the same part of the retina lead you to perceive the person as moving.

Psychologist James J. Gibson thought that this explanation of motion perception was too complicated. He reasoned that perception does not depend on internal thought processes. He thought, instead, that the objects in our environment contain all the information necessary for perception. Think of the aerial acrobatics of a fly. Clearly, the fly is a master of motion and depth perception, yet few people would say the fly makes unconscious inferences. Gibson identified a number of cues for motion detection, including the covering and uncovering of background. Research has shown that motion detection is, in fact, much easier against a background. Thus, as a person moves in front of you, that person first covers and then uncovers portions of the background.

People may perceive motion when none actually exists. For example, motion pictures are really a series of slightly different still pictures flashed on a screen at a rate of 24 pictures, or frames, per second. From this rapid succession of still images, our brain perceives fluid motion - a phenomenon known as stroboscopic movement. For more information about illusions of emotion.

Experience in interacting with the world is vital to perception. For instance, kittens raised without visual experience or deprived of normal visual experience do not perceive the world accurately. In one experiment, researchers reared kittens in total darkness, except that for five hours a day the kittens were placed in an environment with only vertical lines. When the animals were later exposed to horizontal lines and forms, they had trouble perceiving these forms.

Philosophers have long debated the role of experience in human perception. In the late 17th century, Irish philosopher William Molyneux wrote to his friend, English philosopher John Locke, and asked him to consider the following scenario: Suppose that you could restore sight to a person who was blind. Using only vision, would that person be able to tell the difference between a cube and a sphere, which she or he had previously experienced only through touch? Locke, who emphasized the role of experience in perception, thought the answer was no. Modern science actually allows us to address this philosophical question, because a very small number of people who were blind have had their vision restored with the aid of medical technology.

Two researchers, British psychologist Richard Gregory and British-born neurologists’ Oliver Sacks, have written about their experiences with men who were blind for a long time due to cataracts and then had their vision restored late in life. When their vision was restored, they were often confused by visual input and were unable to see the world accurately. For instance, they could detect motion and perceive colors, but they had great difficulty with complex stimuli, such as faces. Much of their poor perceptual ability was probably due to the fact that the synapses in the visual areas of their brains had received little or no stimulation throughout their lives. Thus, without visual experience, the visual system does not develop properly.

Visual experience is useful because it creates memories of past stimuli that can later serve as a context for perceiving new stimuli. Thus, you can think of experience as a form of context that you carry around with you.

Ordinarily, when you read, you use the context of your prior experience with words to process the words you are reading. Context may also occur outside of you, as in the surrounding elements in a visual scene. When you are reading and you encounter an unusual word, you may be able to determine the meaning of the word by its context. Your perception depends on the context.

Although context is useful most of the time, on some rare occasions context can lead you to misperceive a stimulus. Look at Example B in the Context Effects illustration. Which of the green circles is larger? You may have guessed that the green circle on the right is larger. In fact, the two circles are the same size. Your perceptual system was fooled by the context of the surrounding red circles.

Against a background of slanted lines, a perfect square appears trapezoidal - that is, wider at the top than at the bottom. This illusion may occur because the lines create a sense of depth, making the top of the square seems farther away and larger.

A visual illusion occurs when your perceptual experience of a stimulus is substantially different from the actual stimulus you are viewing. In the previous example, you saw the green circles as different sizes, even though they were actually the same size. To experience another illusion, look at the illustration entitled Zöllner Illusion. What shape do you see? You may see a trapezoid that is wider at the top, but the actual shape is a square. Such illusions are natural artifacts of the way our visual systems work. As a result, illusions provide important insights into the functioning of the visual system. In addition, visual illusions are fun to experience.

An ascribing notion to awaiting the idea that something debated finds to its intent of meaning the explicit significance of the same psychology that is immeasurably the scientific study of behavior and the mind. This definition contains three elements. The first is that psychology is a scientific enterprise that obtains knowledge through systematic and objective methods of observation and experimentation. Second is that psychologists study behavior, which refers to any action or reaction that can be measured or observed - such as the blink of an eye, an increase in heart rate, or the unruly violence that often erupts in a mob. Third is that psychologists study the mind, which refers to both conscious and unconscious mental states. These states cannot actually be seen, only inferred from observable behavior.

Many people think of psychologists as individuals who dispense advice, analyze personality, and help those who are troubled or mentally ill. But psychology is far more than the treatment of personal problems. Psychologists strive to understand the mysteries of human nature - why people think, feel, and act as they do. Some psychologists also study animal behavior, using their findings to determine laws of behavior that apply to all organisms and to formulate theories about how humans behave and think.

With its broad scope, psychology investigates an enormous range of phenomena: learning and memory, sensation and perception, motivation and emotion, thinking and language, personality and social behavior, intelligence, infancy and child development, mental illness, and much more. Furthermore, psychologists examine these topics from a variety of complementary perspectives. Some conduct detailed biological studies of the brain. Others explore how we process information; others analyze the role of evolution, and still others study the influence of culture and society.

Psychologists seek to answer a wide range of important questions about human nature: Are individuals genetically predisposed at birth to develop certain traits or abilities? How accurate are people at remembering faces, places, or conversations from the past? What motivates us to seek out friends and sexual partners? Why do so many people become depressed and behave in ways that seem self-destructive? Do intelligence test scores predict success in school, or later in a career? What causes prejudice, and why is it so widespread? Can the mind be used to heal the body? Discoveries from psychology can help to reside in the alignment of oneself with themselves, relate better to others, and solve the problems that confront them.

The term psychology comes from two Greek words: psyche, which means soul, and logos, the study of. These root words were first combined in the 16th century, at a time when the human soul, spirit, or mind was seen as distinct from the body.

Psychology overlaps with other sciences that investigate behavior and mental processes. Certain parts of the field share much with the biological sciences, especially physiology, the biological study of the functions of living organisms and their parts. Like physiologists, many psychologists study the inner workings of the body from a biological perspective. However, psychologists usually focus on the activity of the brain and nervous system.

The social sciences of sociology and anthropology, which study human societies and cultures, also intersect with psychology. For example, both psychology and sociology explore how people behave when they are in groups. However, psychologists try to understand behavior from the vantage point of the individual, whereas sociologists focus on how behavior is shaped by social forces and social institutions. Anthropologists investigate behavior as well, paying particular attention to the similarities and differences between human cultures around the world.

Psychology is closely connected with psychiatry, which is the branch of medicine specializing in mental illnesses. The study of mental illness is one of the largest areas of research in psychology. Psychiatrists and psychologists differ in their training. A person seeking to become a psychiatrist first obtains a medical degree and then engages in further formal medical education in psychiatry. Most psychologists have a doctoral graduate degree in psychology.

The study of psychology draws on two kinds of research: basic and applied. Basic researchers seek to test general theories and build a foundation of knowledge, while applied psychologists study people in real-world settings and use the results to solve practical human problems. There are five major areas of research: biopsychology, clinical psychology, cognitive psychology, developmental psychology, and social psychology. Both basic and applied research is conducted in each of these fields of psychology.

This section describes basic research and other activities of psychologists in the five major fields of psychology. Applied research is discussed in the Practical Applications of Psychology section of this article.

Magnetic resonance imaging (MRI) reveals structural differences between a normal adult brain, left, and the brain of a person with schizophrenia, right. The schizophrenic brain has enlarged ventricles (fluid-filled cavities), shown in light gray. However, not all people with schizophrenia show this abnormality.

How do body and minds interact? Are body and mind fundamentally different parts of a human being, or are they one and the same, interconnected in important ways? Inspired by this classic philosophical debate, many psychologists specialize in biopsychology, the scientific study of the biological underpinnings of behavior and mental processes.

At the heart of this perspective is the notion that human beings, like other animals, have an evolutionary history that predisposes them to behave in ways that are uniquely adaptive for survival and reproduction. Biopsychologists work in a variety of subfields. Researchers in the field of ethology observe fish, reptiles, birds, insects, primates, and other animal species in their natural habitats. Comparative psychologists study animal behavior and make comparisons among different species, including humans. Researchers in evolutionary psychology theorize about the origins of human aggression, altruism, mate selection, and other behaviors. Those in behavioral genetics seek to estimate the extent to which human characteristics such as personality, intelligence, and mental illness are inherited.

Particularly important to biopsychology is a growing body of research in behavioral neuroscience, the study of the links between behavior and the brain and nervous system. Facilitated by computer-assisted imaging techniques that enable researchers to observe the living human brain in action, this area is generating great excitement. In the related area of cognitive neuroscience, researchers record physical activity in different regions of the brain as the subject reads, speaks, solves math problems, or engages in other mental tasks. Their goal is to pinpoint activities in the brain that correspond to different operations of the mind. In addition, many Biopsychologists are involved in psychopharmacology, the study of how drugs affect mental and behavioral functions.

This chart illustrates the percentage of people in the United States who experience a particular mental illness at some point during their lives. The figures are derived from the National Comorbidity Survey, in which researchers interviewed more than eight-thousand people aged from 15 to 54 years. Homeless people and those living in prisons, nursing homes, or other institutions were not included in the survey.

Clinical psychology is dedicated to the study, diagnosis, and treatment of mental illnesses and other emotional or behavioral disorders. More psychologists work in this field than in any other branch of psychology. In hospitals, community clinics, schools, and in private practice, they use interviews and tests to diagnose depression, anxiety disorders, schizophrenia, and other mental illnesses. People with these psychological disorders often suffer terribly. They experience disturbing symptoms that make it difficult for them to work, relate to others, and cope with the demands of everyday life.

Over the years, scientists and mental health professionals have made great strides in the treatment of psychological disorders. For example, advances in psychopharmacology have led to the development of drugs that relieve severe symptoms of mental illness. Clinical psychologists usually cannot prescribe drugs, but they often work in collaboration with a patient’s physician. Drug treatment is often combined with psychotherapy, a form of intervention that relies primarily on verbal communication to treat emotional or behavioral problems. Over the years, psychologists have developed many different forms of psychotherapy. Some forms, such as psychoanalysis, focus on resolving internal, unconscious conflicts stemming from childhood and past experiences. Other forms, such as cognitive and behavioral therapies, focus more on the persons’ current level of functioning and try to help the individual change distressing thoughts, feelings, or behaviors.

In addition to studying and treating mental disorders, many clinical psychologists study the normal human personality and the ways in which individuals differ from one another. Still, others administer a variety of psychological tests, including intelligence tests and personality tests. These tests are commonly given to individuals in the workplace or in school to assess their interests, skills, and level of functioning. Clinical psychologists also use tests to help them diagnose people with different types of psychological disorders.

The field of counseling psychology is closely related to clinical psychology. Counseling psychologists may treat mental disorders, but they more commonly treat people with less-severe adjustment problems related to marriage, family, school, or career. Many other types of professionals care for and treat people with psychological disorders, including psychiatrists, psychiatric social workers, and psychiatric nurses.

To take the Stroop test, names aloud each color in the two columns at left as quickly as you can. Next, look at the right side of the illustration and quickly name the colors in which the words are printed. Which task took longer to complete? The test, devised in 1935 by American psychologist John Stroop, shows that people cannot help but process word meanings, and that this processing interferes with the color-naming task.

How does it become of an acknowledged adherent that from such visual images, facts, and personal memories stored? What causes forgetting? How entangled of greater amounts worth much as much though its qualities were to extend beyond any doubt of dealing with people whose resolving problems or difficulties lapsed within life’s decisions? Does language limit the way people consciously think, by contrast, on the account that if one is unable to think he is definitely not conscious? All the same, because or do people initially attain the work by collecting representational continuities, along with causal continuity, in that thy host of something as a sponsor to gauging its measure by way of a considerable objective, if not to tactfully mark and note the handling collective circumstance of whatever is appended of having actual possessions, that for which can be known as having an existence of our space or time to think? Because of their state of awareness to consciousness? And to what extent are people influenced by information outside of conscious awareness?

These are the kinds of questions posed within cognitive psychology, the scientific study of how people acquire, processes, and utilize information. Cognition refers to the process of knowing and encompasses nearly the entire range of conscious and unconscious mental processes: sensation and perception, conditioning and learning, attention and consciousness, sleep and dreaming, memory and forgetting, reasoning and decision making, imagining, problem solving, and language.

Decades ago, the invention of digital computers gave cognitive psychologists a powerful new way of thinking about the human mind. They began to see human beings as information processors who receive input, process and store information, and produce output. This approach became known as the information-processing model of cognition. As computers have become more sophisticated, cognitive psychologists have extended the metaphor. For example, most researchers now reject the idea that information is processed in linear, sequential steps. Instead they find that the human mind is capable of parallel processing, in which multiple operations are carried out simultaneously.

In this information-processing model of memory, information that enters the brain is briefly recorded in sensory memory. If we focus our attention on it, the information may become part of working memory (also called short-term memory), where it can be manipulated and used. Through encoding techniques such as repetition and rehearsal, information may be transferred to long-term memory. Retrieving long-term memories makes them active again in working memory.

Are people programmed by inborn biological dispositions? Or is an individuals fate molded by culture, family, peers, and other socializing influences within the environment? These questions about the roles of nature and nurture are central to the study of human development.

An incredibly complex array of influences, including families, acquaintances, mass media, and society as a whole, help determine the moral development of children. Although a rash of violent incidents in American schools in the late 1990s focused attention on deviant youth behavior, the vast majority of children seem to function harmoniously with others. In this August 1999 article from Scientific American, William Damon, director of the Center on Adolescence at Stanford University in California, explores recent findings on how young people develop morality.

Developmental psychology focuses on the changes that come with age. By comparing people of different ages, and by tracking individuals over time, researchers in this area study the ways in which people mature and change over the life span. Within this area, those who specialize in child development or child psychology study physical, intellectual, and social development in fetuses, infants, children, and adolescents. Recognizing that human development is a lifelong process, other developmental psychologists study the changes that occur throughout adulthood. Still others specialize in the study of old age, even the process of dying.

A shock generator, top, was used by American psychologist Stanley Milgram in experiments designed to test the obedience of people to authority. An experimenter instructed subjects to administer what they believed were painful electric shocks to Mr. Wallace, bottom, an accomplice of the experimenter who was strapped into a chair and connected to the generator by electrodes on his skin. No actual shocks occurred. The experimenter ordered the subjects to continue as the shocks increased to a level the subjects believed were dangerous or even lethal. In Milgrams initial study, 65 percent of people obeyed the experimenter and delivered the maximum shock of 450 volts. Milgram discusses his conclusions in this sound clip.

Social psychology is the scientific study of how people think, feel, and behave in social situations. Researchers in this field ask questions such as, How do we form impressions of others? How are people persuaded to change their attitudes or beliefs? What causes people to conform with group situations? What leads someone to help or ignore a persons need? Under what circumstances do people feel that their obligation or resist by orders of causal necessity that someone is bound to do or to forbear the committal validations for which occasion indigently toward something as free-will and willfulness, if be to existential choice is given to mean by some untold story of being human, Such is the nonobligatory collective sustentation or an idea of an expression deficient in originality of freshness, for which in exchanging commonplace or matter-of-course interchanging of ordinary common courtesy,

By observing people in real-world social settings, and by carefully devising experiments to test people’s social behavior, social psychologists learn about the ways people influence, perceives, and interact with one another. The study of social influence includes topics such as conformity, obedience to authority, the formation of attitudes, and the principles of persuasion. Researchers interested in social perception study how people come to know and evaluate one another, how people form group stereotypes, and the origins of prejudice. Other topics of particular interest to social psychologists include physical attraction, love and intimacy, aggression, altruism, and group processes. Many social psychologists are also interested in cultural influences on interpersonal behavior.

Whereas basic researchers test theories about mind and behavior, applied psychologists are motivated by a desire to solve practical human problems. Four particularly active areas of application are health, education, business, and law.

Today, many psychologists work in the emerging area of health psychology, the application of psychology to the promotion of physical health and the prevention and treatment of illness. Researchers in this area have shown that human health and well-being depends on both biological and psychological factors.

Many psychologists in this area study psychophysiological disorders (also called psychosomatic disorders), conditions that are brought on or influenced by psychological states, most often stress. These disorders include high blood pressure, headaches, asthma, and ulcers. Researchers have discovered that chronic stress is associated with an increased risk of coronary heart disease. In addition, stress can compromise the bodies’ immune system and increase susceptibility to illness.

Health psychologists also study how people cope with stress. They have found that people who have family, friends, and other forms of social support are healthier and live longer than those who are more isolated. Other researchers in this field examine the psychological factors that underlie smoking, drinking, drug abuse, risky sexual practices, and other behaviors harmful to health.

Psychologists in all branches of the discipline contribute to our understanding of teaching, learning, and education. Some help develops standardized tests used to measure academic aptitude and achievement. Others study the ages at which children become capable of attaining various cognitive skills, the effects of rewards on their motivation to learn, computerized instruction, bilingual education, learning disabilities, and other relevant topics. Perhaps the best-known application of psychology to the field of education occurred in 1954 when, in the case of Brown v Board of Education, the Supreme Court of the United States outlawed the segregation of public schools by race. In its ruling, the Court cited psychological studies suggesting that segregation had a damaging effect on black students and tended to encourage prejudice.

In addition to the contributions of psychology as a whole, two fields within psychology focus exclusively on education: educational psychology and school psychology. Educational psychologists seek to understand and improve the teaching and learning process within the classroom and other educational settings. Educational psychologists study topics such as intelligence and ability testing, student motivation, discipline and classroom management, curriculum plans, and grading. They also test general theories about how students learn most effectively. School psychologists work in elementary and secondary school systems administering tests, making placement recommendations, and counseling children with academic or emotional problems.

The business world, psychology is applied in the workplace and in the marketplace. Industrial-organizational (I-O) psychology focuses on human behavior in the workplace and other organizations. I-O psychologists conduct research, teach in business schools or universities, and work in private industry. Many I-O psychologists study the factors that influence worker motivation, satisfaction, and productivity. Others study the personal traits and situations that foster great leadership. Still, others focus on the processes of personnel selection, training, and evaluation. Studies have shown, for example, that face-to-face interviews sometimes result in poor hiring decisions and may be biased by the applicants gender, race, and physical attractiveness. Studies have also shown that certain standardized tests can help to predict on-the-job performance.

Consumer psychology is the study of human decision making and behavior in the marketplace. In this area, researchers analyze the effects of advertising on consumers’ attitudes and buying habits. Consumer psychologists also study various aspects of marketing, such as the effects of packaging, price, and other factors that lead people to purchase one product rather than another.

Many psychologists today work in the legal system. They consult with attorneys, testify in court as expert witnesses, counsel prisoners, teach in law schools, and research various justice-related issues. Sometimes referred to as forensic psychologists, those who apply psychology to the law study a range of issues, including jury selection, eyewitness testimony, confessions to police, lie-detector tests, the death penalty, criminal profiling, and the insanity defense.

Studies in forensic psychology have helped to illuminate weaknesses in the legal system. For example, based on trial-simulation experiments, researchers have found that jurors are often biased by various facts not in evidence - that is, facts the judge tells them to disregard. In studying eyewitness testimony, researchers have staged mock crimes and asked witnesses to identify the assailant or recall other details. These studies have revealed that under certain condition’s eyewitnesses are highly prone to error.

Psychologists in this area often testify in court as expert witnesses. In cases involving the insanity defense, forensic clinical psychologists are often called to court to give their opinion about whether individual defendants are sane or insane. Used as a legal defense, insanity means that defendants, because of a mental disorder, cannot appreciate the wrongfulness of their conduct or control it. Defendants who are legally insane at the time of the offense may be absolved of criminal responsibility for their conduct and judged not guiltily. Psychologists are often called to testify in court on other controversial matters as well, including the accuracy of eyewitness testimony, the mental competence (fitness) of defendants to stand trial, and the reliability of early childhood memories.

Psychology has applications in many other domains of human life. Environmental psychologists focus on the relationship between people and their physical surroundings. They study how street noise, heat, architectural design, population density, and crowding affect peoples behavior and mental health. In a related field, human factors’ psychologists work on the design of appliances, furniture, tools, and other manufactured items in order to maximize their comfort, safety, and convenience. Sports psychologists advise athletes and study the physiological, perceptual-motor, motivational, developmental, and social aspects of athletic performance. Other psychologists specialize in the study of political behavior, religion, sexuality, or behavior in the military.

Psychologists from all areas of specialization use the scientific method to test their theories about behavior and mental processes. A theory is an organized set of principles that is designed to explain and predict some phenomenon. Good theories also provide specific testable predictions, or hypotheses, about the relation between two or more variables. Formulating a hypothesis to be tested is the first important step in conducting research.

Over the years, psychologists have devised numerous ways to test their hypotheses and theories. Many studies are conducted in a laboratory, usually located at a university. The laboratory setting allows researchers to control what happens to their subjects and make careful and precise observations of behavior. For example, a psychologist who studies memory can bring volunteers into the lab, ask them to memorize a list of words or pictures, and then test their recall of that material seconds, minutes, or days later.

As indicated by the term field research, studies may also be conducted in real-world locations. For example, a psychologist investigating the reliability of eyewitness testimony might stage phony crimes in the street and then ask unsuspecting bystanders to identify the culprit from a set of photographs. Psychologists observe people in a wide variety of other locations outside the laboratory, including classrooms, offices, hospitals, college dormitories, bars, restaurants, and prisons.

In both laboratory and field settings, psychologists conduct their research using a variety of methods. Among the most common methods are archival studies, case studies, surveys, naturalistic observations, correlational studies, experiments, literature reviews, and measures of brain activity.

One way to learn about people is through archival studies, an examination of existing records of human activities. Psychological researchers often examine old newspaper stories, medical records, birth certificates, crime reports, popular books, and artwork. They may also examine statistical trends of the past, such as crime rates, birth rates, marriage and divorce rates, and employment rates. The strength of such measures is that by observing people only secondhand, researchers cannot unwittingly influence the subjects by their presence. However, available records of human activity are not always complete or detailed enough to be useful.

Archival studies are particularly valuable for examining cultural or historical trends. For example, in one study of physical attractiveness, researchers wanted to know if American standards of female beauty have changed over several generations. These researchers looked through two popular womens magazines between 1901 and 1981 and examined the measurements of the female models. They found that curvaceousness (as measured by the bust-to-waist ratio) varied over time, with a boyish, slender look considered desirably in some time periods but not in others.

Sometimes psychologists interview, test, observe, and investigate the backgrounds of specific individuals in detail. Such case studies are conducted when researchers believe that an in-depth look at one individual will reveal something important about people in general.

Case studies often taken as a great deal of time to complete, and the results may be limited by the fact that the subject is atypical. Yet case studies have played a prominent role in the development of psychology. Austrian physician Sigmund Freud based his theory of psychoanalysis on his experiences with troubled patients. Swiss psychologist Jean Piaget first began to formulate a theory of intellectual development by questioning his own children. Neurophysiologist learn about how the human brain works by testing patients who have suffered brain damage. Cognitive psychologists learn about human intelligence by studying child prodigies and other gifted individuals. Social psychologists learn about group decision making by analyzing the policy decisions of government and business groups. When an individual is exceptional in some way, or when a hypothesis can be tested only through intensive, long-term observation, the case study is a valuable method.

An electroencephalogram, or EEG, is a recording of the action potential, or electrical, activity of the cerebral cortex of the brain. An EEG is made by attaching electrodes to the scalp, then collecting, amplifying, and recording the electrical impulses of the brain.

Biopsychologists interested in the links between brain and behaviors use a variety of specialized techniques in their research. One approach is to observe and test patients who have suffered damage to a specific region of the brain to determine what mental functions and behaviors were affected by that damage. British-born neurologist Oliver Sacks has written several books in which he describes case studies of brain-damaged patients who exhibited specific deficits in their speech, memory, sleep, and even in their personalities.

This positron emission tomography (PET) scans of the brain shows the activity of brain cells in the resting state and during three types of auditory stimulation. PET uses radioactive substances introduced into the brain to measure such brain functions as cerebral metabolism, blood flow and volume, oxygen use, and the formation of neurotransmitters. This imaging method collects data from many different angles, feeding the information into a computer that produces a series of cross-sectional images.

A second approach is too physically altering the brain and measures the effects of that change on behavior. The alteration can be achieved in different ways. For example, animal researchers often damage or destroy a specific region of a laboratory animals brain through surgery. Other researchers might spark or inhibit activity in the brain through the use of drugs or electrical stimulation.

This magnetic resonance imaging (MRI) scans of a normal adult head shows the brain, airways, and soft tissues of the face. The large cerebral cortex, appearing in yellow and green, forms the bulk of the brain tissue; the circular cerebellum, center left, in red, and the elongated brainstem, centers, in red, are also prominently shown.

Another way to study the relationship between the brain and behavior is to record the activity of the brain with machines while a subject engages in certain behaviors or activities. One such instrument is the electroencephalograph, a device that can detect, amplifies, and record the level of electrical activity in the brain by means of metal electrodes taped to the scalp.

Advances in technology in the early 1970s allowed psychologists to see inside the living human brain for the first time without physically cutting into it. Today, psychologists use a variety of sophisticated brain-imaging techniques. The computerized axial tomography (CT or CAT) scan provides a computer-enhanced X-ray image of the brain. The more advanced positron emission tomography (PET) scans tracks the level of activity in specific parts of the brain by measuring the amount of glucose being used there. These measurements are then fed to a computer, which produces a color-coded image of brain activity. Another technique is magnetic resonance imaging (MRI), which produces high-resolution cross-sectional images of the brain. A high-speed version of MRI known as functional MRI produces moving images of the brain as its activity changes in real time. These relatively new brain imaging techniques have generated great excitement, because they allow researchers to identify parts of the brain that are active while people read, speak, listen to music, solve math problems, and engage in other mental activities.

In contrast with the in-depth study of one person, surveys describe a specific population or group of people. Surveys involve asking people a series of questions about their behaviors, thoughts, or opinions. Surveys can be conducted in person, over the phone, or through the mail. Most surveys study a specific group - for example, college students, working mothers, men, or homeowners. Rather than questioning every person in the group, survey researchers choose a representative sample of people and generalize the findings to the larger population.

Surveys may pertain to almost any topic. Often surveys ask people to report their feelings about various social and political issues, the TV shows they watch, or the consumers products they purchase. Surveys are also used to learn about peoples sexual practices; to estimate the use of cigarettes, alcohol, and other drugs; and to approximate the proportion of people who experience feelings of life satisfaction, loneliness, and other psychological states that cannot be directly observed.

Surveys must be carefully designed and conducted to ensure their accuracy. The results can be influenced, and biased, by two factors: who the respondents are and how the questions are asked. For a survey to be accurate, the sample being questioned must be representative of the population on key characteristics such as sex, race, age, region, and cultural background. To ensure similarity to the larger population, survey researchers usually try to make sure that they have a random sample, a method of selection in which everyone in the population has an equal chance of being chosen.

In naturalistic observation, the researcher observes people as they behave in the real world. The researcher simply records what occurs and does not intervene in the situation. Psychologists use naturalistic observation to study the interactions between parents and children, doctors and patients, police and citizens, and managers and workers.

Naturalistic observation is common in anthropology, in which field workers seek to understand the everyday life of a culture. Ethologists, who study the behavior of animals in their natural habitat, also use this method. For example, British ethologist Jane Goodall spent many years in African jungles observing chimpanzees - their social structure, courting rituals, struggles for dominance, eating habits, and other behaviors. Naturalistic observation is also common among developmental psychologists who study social play, parent-child attachments, and other aspects of child development. These researchers observe children at home, in school, on the playground, and in other settings.

Case studies, surveys, and naturalistic observations are used to describe behavior. Correlational studies are further designed to find statistical connections, or correlations, between variables so that some factors can be used to predict others.

A correlation is a statistical measure of the extent to which two variables are associated. A positive correlation exists when two variables increase or decrease together. For example, frustration and aggression are positively correlated, meaning that as frustration rises, so do acts of aggression. More of one means more of the other. A negative correlation exists when increases in one variable are accompanied by decreases in the other, and vice versa. For example, friendships and stress-induced illness are negatively correlated, meaning that the more close friends a person has, the fewer stress-related illnesses the person suffers. More of one means less of the other.

Based on correlational evidence, researchers can use one variable to make predictions about another variable. But researchers must use caution when drawing conclusions from correlations. It is nature - but incorrect - to assume that because one variable predicts another, the first must have caused the second. For example, one might assume that frustration triggers aggression, or that friendships foster health. Regardless of how intuitive or accurate these conclusions may be, correlation does not prove causation. Thus, although it is possible that frustration causes aggression, there are other ways to interpret the correlation. For example, it is possible that aggressive people are more likely to suffer social rejection and become frustrated as a result.

Correlations enable researchers to predict one variable from another. But to determine if one variable actually causes another, psychologists must conduct experiments. In an experiment, the psychologist manipulates one factor in a situation - keeping other aspects of the situation constant - and then observes the effect of the manipulation on behavior. The people whose behavior is being observed are the subjects of the experiment. The factor that an experimenter varies (the proposed cause) is known as the independent variable, and the behavior being measured (the proposed effect) is called the dependent variable. In a test of the hypothesis that frustration triggers aggression, frustration would be the independent variable, and aggression the dependent variable.

There are three requirements for conducting a valid scientific experiment: (1) control over the independent variable, (2) the use of a comparison group, and (3) the random assignment of subjects to conditions. In its most basic form, then, a typical experiment compares a large number of subjects who are randomly assigned to experience one condition with a group of similar subjects who are not. Those who experience the condition compose the experimental group, and those who do not make up the control group. If the two groups differ significantly in their behavior during the experiment, that difference can be attributed to the presence of the condition, or independent variable. For example, to test the hypothesis that frustration triggers aggression, one group of researchers brought subjects into a laboratory, impeded their efforts to complete an important task (other subjects in the experiment were not impeded), and measured their aggressiveness toward another person. These researchers found that subjects who had been frustrated were more aggressive than those who had not been frustrated.

Psychologists use many different methods in their research. Yet no single experiment can fully prove a hypothesis, so the science of psychology builds slowly over time. First, a new discovery must be replicated. Replication refers to the process of conducting a second, nearly identical study to see if the initial findings can be repeated. If so, then researchers try to determine if these findings can be applied, transferred, or generalized to other settings. Generalizability refers to the extent to which a finding obtained less than one set of conditions can also be obtained at another time, in another place, and in other populations.

Because the science of psychology proceeds in small increments, many studies must be conducted before clear patterns emerge. To summarize and interpret an entire body of research, psychologists rely on two methods. One method is a narrative review of the literature, in which a reviewer subjectively evaluates the strengths and weaknesses of the various studies on a topic and argues for certain conclusions. Another method is meta-analysis, a statistical procedure used to combine the results from many different studies. By meta-analyzing a body of research, psychologists can often draw precise conclusions concerning the strength and breadth of support for a hypothesis.

Psychological research involving human subject raises ethical concerns about the subjects right to privacy, the possible harm or discomfort caused by experimental procedures, and the use of deception. Over the years, psychologists have established various ethical guidelines. The American Psychological Association recommends that researchers (1) tell prospective subjects what they will experience so they can give informed consent to participate; (2) instruct subjects that they may withdraw from the study at any time; (3) minimize all harm and discomfort; (4) keep the subjects responses and behaviors confidential; and (5) debrief subjects who were deceived in some way by fully explaining the research after they have participated. Some psychologists argue that such rules should never be broken. Others say that some degree of flexibility is needed in order to study certain important issues, such as the effects of stress on test performance.

Laboratory experiments that use rats, mice, rabbits, pigeons, monkeys, and other animals are an important part of psychology, just as in medicine. Animal research serves three purposes in psychology: to learn more about certain types of animals, to discover general principles of behavior that pertain to all species, and to study variables that cannot ethically be tested with human beings. But is it ethical to experiment on animals?

Some animal rights activists believe that it is wrong to use animals in experiments, particularly in those that involve surgery, drugs, social isolation, food deprivation, electric shock, and other potentially harmful procedures. These activists see animal experimentation as unnecessary and question whether results from such research can be applied to humans. Many activists also argue that like humans, animals have the capacity to suffer and feel pain. In response to these criticisms, many researchers point out that animal experimentation has helped to improve the quality of human life. They note that animal studies have contributed to the treatment of anxiety, depression, and other mental disorders. Animal studies have also contributed to our understanding of conditions such as Alzheimer disease, obesity, alcoholism, and the effects of stress on the immune system. Most researchers follow strict ethical guidelines that require them to minimize pain and discomfort to animals and to use the least invasive procedures possible. In addition, federal animal-protection laws in the United States require researchers to provide humane care and housing of animals and to tend to the psychological well-being of primates used in research.

One of the youngest sciences, psychology did not emerge as a formal discipline until the late 19th century. But its roots extend to the ancient past. For centuries, philosophers and religious scholars have wondered about the nature of the mind and the soul. Thus, the history of psychological thought begins in philosophy.

From about 600 to 300 Bc, Greek philosophers inquired about a wide range of psychological topics. They were especially interested in the nature of knowledge and how human beings come to know the world, a field of philosophy known as epistemology. The Greek philosopher Socrates and his followers, Plato and Aristotle, wrote about pleasure and pain, knowledge, beauty, desire, free will, motivation, common sense, rationality, memory, and the subjective nature of perception. They also theorized about whether human traits are innate or the product of experience. In the field of ethics, philosophers of the ancient world probed a variety of psychological questions: Are people inherently good? How can people attain happiness? What motives or drives do people have? Are human beings naturally social?

Second-century physician Galen was one of the most influential figures in ancient medicine, second in importance only to Hippocrates. Using animal dissection and other means, Galen proposed numerous theories about the function of different parts of the human body, most notably the brain, heart, and liver. He also derived an impressive understanding of the differences between veins and arteries. In the selection below, Galen discusses his idea that the optimal state, or constitution, of the body should be a perfect balance of various internal and external components.

Early thinkers also considered the causes of mental illness. Many ancient societies thought that mental illness resulted from supernatural causes, such as the anger of gods or possession by evil spirits. Both Socrates and Plato focused on psychological forces as the cause of mental disturbance. For example, Plato thought madness results when a persons irrational, animal-like psyche (mind or soul) overwhelms the intellectual, rational psyche. The Greek physician Hippocrates viewed mental disorders as stemming from natural causes, and he developed the first classification system for mental disorders. Galen, a Greek physician who lived in the 2nd century ad, echoed this belief in a physiological basis for mental disorders. He thought they resulted from an imbalance of the four bodily humors: black bile, yellow bile, blood, and phlegm. For example, Galen thought that melancholia (depression) resulted from a person having too much black bile.

More recently, many other men and women contributed to the birth of modern psychology. In the 1600s French mathematician and philosopher René Descartes theorized that the body and mind are separate entities. He regarded the body as a physical entity and the mind as a spiritual entity, and believed the two interacted only through the pineal gland, a tiny structure at the base of the brain. This position became known as dualism. According to dualism, the behavior of the body is determined by mechanistic laws and can be measured in a scientific manner. But the mind, which transcends the material world, cannot be similarly studied.

English philosophers Thomas Hobbes and John Locke disagreed. They argued that all human experiences - including sensations, images, thoughts, and feelings - are physical processes occurring within the brain and nervous system. Therefore, these experiences are valid subjects of study. In this view, which later became known as monism, the mind and body are one and the same. Today, in light of years of research indicating that the physical and mental aspects of the human experience are intertwined, most psychologists reject a rigid dualists position.

Many philosophers of the past also debated the question of whether human knowledge is inborn or the product of experience. Nativists believed that certain elementary truths are innate to the human mind and need not be gained through experience. In contrast, empiricist believed that at birth, a persons mind is like a tabula rasa, or blank slate, and that all human knowledge ultimately comes from sensory experience. Today, all psychologists agree that both types of factors are important in the acquisition of knowledge.

Modern psychology can also be traced to the study of physiology (a branch of biology that studies living organisms and their parts) and medicine. In the 19th century, physiologists began studying the human brain and nervous system, paying particular attention to the topic of sensation. For example, in the 1850s and 1860s German scientist Hermann von Helmholtz studied sensory receptors in the eye and ear, investigating topics such as the speed of neural impulses, color vision, hearing, and space perception. Another important German scientist, Gustav Fechner, founded psychophysics, the study of the relationship between physical stimuli and our subjective sensations of those stimuli. Building on the work of his compatriot Ernst Weber, Fechner developed a technique for measuring peoples subjective sensations of various physical stimuli. He sought to determine the minimum intensity level of a stimulus that is needed to produce a sensation.

English naturalist Charles Darwin was particularly influential in the development of psychology. In 1859 Darwin published On the Origin of Species, in which he proposed that all living forms were a product of the evolutionary process of natural selection. Darwin had based his theory on plants and nonhuman animals, but he later asserted that people had evolved through similar processes, and that human anatomy and behavior could be analyzed in the same way. Darwins theory of evolution invited comparisons between humans and other animals, and scientists soon began using animals in psychological research.

French neurologist Jean Martin Charcot shows colleagues a female patient with hysteria at La Salpêtrière, a Paris hospital. Charcot gained renown throughout Europe for his method of treating hysteria and other nervous disorders through hypnosis. Charcots belief that hysteria had psychologically rather than physical origins influenced Austrian neurologist Sigmund Freud, who studied under Charcot.

In medicine, physicians were discovering new links between the brain and language. For example, French surgeon Paul Broca discovered that people who suffer damage to a specific part of the brains left hemispheres losing the ability to produce fluent speech. This area of the brain became known as Brocas area. A German neurologist, Carl Wernicke, reported in 1874 that people with damage to a different area of the left hemisphere lose their ability to comprehend speech. This region became known as Wernickes area.

Other physicians focused on the study of mental disorders. In the late 19th century, French neurologist Jean Charcot discovered that some of the patients he was treating for so-called nervous disorders could be cured through hypnosis, a psychological - not medical - form of intervention. Charcots work had a profound impact on Sigmund Freud, an Austrian neurologist whose theories would later revolutionize psychology.

Austrian physician Franz Fredrich Anton Mesmer pioneered the induction of trance-like states to cure medical ailments. Mesmers work sparked interest among some of his scientific colleagues but was later dismissed as charlatanism. Today, however, Mesmer is considered a pioneer in hypnosis, which is widely believed to be helpful in managing certain medical conditions.

Psychology was predated and somewhat influenced by various pseudoscientific schools of thought - that is, theories that had no scientific foundation. In the late 18th and early 19th centuries, Viennese physician Franz Joseph Gall developed phrenology, the theory that psychological traits and abilities reside in certain parts of the brain and can be measured by the bumps and indentations in the skull. Although phrenology found popular acceptance among the lay public in western Europe and the United States, most scientists ridiculed Galls ideas. However, research later confirmed the more general point that certain mental activities can be traced to specific parts of the brain.

Physicians in the 18th and 19th centuries used crude devices to treat mental illness, none of which offered any real relief. The circulating swing, top left, was used to spin depressed patients at high speed. American physician Benjamin Rush devised the tranquilizing chair, top right, to calm people with mania. The crib, bottom, was widely used to restrain violent patients.

Another Viennese physician of the 18th century, Franz Anton Mesmer, believed that illness was caused by an imbalance of magnetic fluids in the body. He believed he could restore the balance by passing his hands across the patients body and waving a magnetic wand over the infected area. Mesmer claimed that his patients would fall into a trance and awaken from it feeling better. The medical community, however, soundly rejected the claim. Today, Mesmers technique, known as mesmerism, is regarded as an early forerunner of modern hypnosis.

Modern psychology is deeply rooted in the older disciplines of philosophy and physiology. But the official birth of psychology is often traced to 1879, at the University of Leipzig, in Leipzig, Germany. There, physiologist Wilhelm Wundt established the first laboratory dedicated to the scientific study of the mind. Wundt’s laboratory soon attracted leading scientists and students from Europe and the United States. Among these were James McKeen Cattell, one of the first psychologists to study individual differences through the administration of mental tests, Emil Kraepelin, a German psychiatrist who postulated a physical cause for mental illnesses and in 1883 published the first classification system for mental disorders; and Hugo Münsterberg, the first to apply psychology to industry and the law. Wundt was extraordinarily productive over the course of his career. He supervised a total of 186 doctoral dissertations, taught thousands of students, founded the first scholarly psychological journal, and published innumerable scientific studies. His goal, which he stated in the preface of a book he wrote, was to mark out a new domain of science.

Compared to the philosophers who preceded him, Wundts approach to the study of mind was based on systematic and rigorous observation. His primary method of research was introspection. This technique involved training people to concentrate and report on their conscious experiences as they reacted to visual displays and other stimuli. In his laboratory, Wundt systematically studied topics such as attention span, reaction time, vision, emotion, and time perception. By recruiting people to serve as subjects, varying the conditions of their experience, and then rigorously repeating all observations, Wundt laid the foundation for the modern psychology experiment.

In the United States, Harvard University professor William James observed the emergence of psychology with great interest. Although trained in physiology and medicine, James was fascinated by psychology and philosophy. In 1875 he offered his first course in psychology. In 1890 James published a two-volume book entitled Principles of Psychology. It immediately became the leading psychology text in the United States, and it brought James a worldwide reputation as a man of great ideas and inspiration. In 28 chapters, James wrote about the stream of consciousness, the formation of habits, individuality, the link between mind and body, emotions, the self, and other topics that inspired generations of psychologists. Today, historians consider James the founder of American psychology.

James students also made lasting contributions to the field. In 1883 G. Stanley Hall (who also studied with Wundt) established the first true American psychology laboratory in the United States at Johns Hopkins University, and in 1892 he founded and became the first president of the American Psychological Association. Mary Whiton Calkins created an important technique for studying memory and conducted one of the first studies of dreams. In 1905 she was elected the first female president of the American Psychological Association. Edward Lee Thorndike conducted some of the first experiments on animal learning and wrote a pioneering textbook on educational psychology.

During the first decades of psychology, two main schools of thought dominated the field: structuralism and functionalism. Structuralism was a system of psychology developed by Edward Bradford Titchener, an American psychologist who studied under Wilhelm Wundt. Structuralists believed that the task of psychology is to identify the basic elements of consciousness in much the same way that physicists break down the basic particles of matter. For example, Titchener identified four elements in the sensation of taste: sweet, sour, salty, and bitter. The main method of investigation in structuralism was introspection. The influence of structuralism in psychology faded after Titcheners death in 1927.

In contradiction to the Structuralists movement, William James promoted a school of thought known as functionalism, the belief that the real task of psychology is to investigate the function, or purpose, of consciousness rather than its structure. James was highly influenced by Darwins evolutionary theory that all characteristics of a species must serve some adaptive purpose. Functionalism enjoyed widespread appeal in the United States. Its three main leaders were James Rowland Angell, a student of James; John Dewey, who was also one of the foremost American philosophers and educators; and Harvey A. Carr, a psychologist at the University of Chicago.

In their efforts to understand human behavioral processes, the functional psychologists developed the technique of longitudinal research, which consists of interviewing, testing, and observing one person over a long period of time. Such a system permits the psychologist to observe and record the persons development and how he or she reacts to different circumstances.

In the late 19th century Viennese neurologist Sigmund Freud developed a theory of personality and a system of psychotherapy known as psychoanalysis. According to this theory, people are strongly influenced by unconscious forces, including innate sexual and aggressive drives. In this 1938 British Broadcasting Corporation interview, Freud recounts the early resistance to his ideas and later acceptance of his work. Freuds speech is slurred because he was suffering from cancer of the jaw. He died the following year.

Alongside Wundt and James, a third prominent leader of the new psychology was Sigmund Freud, a Viennese neurologist of the late 19th and early 20th century. Through his clinical practice, Freud developed a very different approach to psychology. After graduating from medical school, Freud treated patients who appeared to suffer from certain ailments but had nothing physically wrong with them. These patients were not consciously faking their symptoms, and often the symptoms would disappear through hypnosis, or even just by talking. On the basis of these observations, Freud formulated a theory of personality and a form of psychotherapy known as psychoanalysis. It became one of the most influential schools of Western thought of the 20th century.

Freud introduced his new theory in The Interpretation of Dreams (1889), the first of 24 books he would write. The theory is summarized in Freuds last book, An Outline of Psychoanalysis, published in 1940, after his death. In contrast to Wundt and James, for whom psychology was the study of conscious experience, Freud believed that people are motivated largely by unconscious forces, including strong sexual and aggressive drives. He likened the human mind to an iceberg: The small tip that floats on the water is the conscious part, and the vast region beneath the surface comprises the unconscious. Freud believed that although unconscious motives can be temporarily suppressed, they must find a suitable outlet in order for a person to maintain a healthy personality.

To probe the unconscious mind, Freud developed the psychotherapy technique of free association. In free association, the patient reclines and talks about thoughts, wishes, memories, and whatever else comes to mind. The analyst tries to interpret these verbalizations to determine their psychological significance. In particular, Freud encouraged patients to free associate about their dreams, which he believed were the royal road to the unconscious. According to Freud, dreams are disguised expressions of deep, hidden impulses. Thus, as patients recount the conscious manifest content of dreams, the psychoanalyst tries to unmask the underlying latent content - what the dreams really mean.

From the start of psychoanalysis, Freud attracted followers, many of whom later proposed competing theories. As a group, these neo-Freudians shared the assumption that the unconscious plays an important role in a persons thoughts and behaviors. Most parted company with Freud, however, over his emphasis on sex as a driving force. For example, Swiss psychiatrist Carl Jung theorized that all humans inherit a collective unconscious that contains universal symbols and memories from their ancestral past. Austrian physician Alfred Adler theorized that people are primarily motivated to overcome inherent feelings of inferiority. He wrote about the effects of birth order in the family and coined the term sibling rivalry. Karen Horney, a German-born American psychiatrist, argued that humans have a basic need for love and security, and become anxious when they feel isolated and alone.

Motivated by a desire to uncover unconscious aspects of the psyche, psychoanalytic researchers devised what are known as projective tests. A projective test asks people to respond to an ambiguous stimulus such as a word, an incomplete sentence, an inkblot, or an ambiguous picture. These tests are based on the assumption that if a stimulus is vague enough to accommodate different interpretations, then people will use it to project their unconscious needs, wishes, fears, and conflicts. The most popular of these tests are the Rorschach Inkblot Test, which consists of ten inkblots, and the Thematic Apperception Test, which consists of drawings of people in ambiguous situations.

Psychoanalysis has been criticized on various grounds and is not as popular as in the past. However, Freuds overall influence on the field has been deep and lasting, particularly his ideas about the unconscious. Today, most psychologists agree that people can be profoundly influenced by unconscious forces, and that people often have a limited awareness of why they think, feel, and behave as they do.

In 1885 German philosopher Hermann Ebbinghaus conducted one of the first studies on memory, using himself as a subject. He memorized lists of nonsense syllables and then tested his memory of the syllables at intervals ranging from 20 minutes to 31 days. As shown in this curve, he found that he remembered less than 40 percent of the items after nine hours, but that the rate of forgetting leveled off over time.

In addition to Wundt, James, and Freud, many others scholars helped to define the science of psychology. In 1885 German philosopher Hermann Ebbinghaus conducted a series of classic experiments on memory, using nonsense syllables to establish principles of retention and forgetting. In 1896 American psychologist Lightner Witmer opened the first psychological clinic, which initially treated children with learning disorders. He later founded the first journal and training program in a new helping profession that he named clinical psychology. In 1905 French psychologist Alfred Binet devised the first major intelligence test in order to assess the academic potential of schoolchildren in Paris. The test was later translated and revised by Stanford University psychologist Lewis Terman and is now known as the Stanford-Binet intelligence test. In 1908 American psychologist Margaret Floy Washburn (who later became the second female president of the American Psychological Association) wrote an influential book called The Animal Mind, in which she synthesized animal research to that time.

In 1912 German psychologist Max Wertheimer discovered that when two stationary lights flash in succession, people see the display as a single light moving back and forth. This illusion inspired the Gestalt psychology movement, which was based on the notion that people tend to perceive a well-organized whole or pattern that is different from the sum of isolated sensations. Other leaders of Gestalt psychology included Wertheimers close associates Wolfgang Köhler and Kurt Koffka. Later, German American psychologist Kurt Lewin extended Gestalt psychology to studies of motivation, personality, social psychology, and conflict resolution. German American psychologist Fritz Heider then extended this approach to the study of how people perceive themselves and others.

In the late 19th century, American psychologist Edward L. Thorndike conducted some of the first experiments on animal learning. Thorndike formulated the law of effect, which states that behaviors that are followed by pleasant consequences will be more likely to be repeated in the future.

William James had defined psychology as the science of mental life. But in the early 1900s, growing numbers of psychologists voiced criticism of the approach used by scholars to explore conscious and unconscious mental processes. These critics doubted the reliability and usefulness of the method of introspection, in which subjects are asked to describe their own mental processes during various tasks. They were also critical of Freuds emphasis on unconscious motives. In search of more-scientific methods, psychologists gradually turned away from research on invisible mental processes and began to study only behavior that could be observed directly. This approach, known as behaviorism, ultimately revolutionized psychology and remained the dominant school of thought for nearly 50 years.

Russian physiologist Ivan Pavlov discovered a major type of learning, classical conditioning, by accident while conducting experiments on digestion in the early 1900s. He devoted the rest of his life to discovering the underlying principles of classical conditioning.

Among the first to lay the foundation for the new behaviorism was American psychologist Edward Lee Thorndike. In 1898 Thorndike conducted a series of experiments on animal learning. In one study, he put cats into a cage, put food just outside the cage, and timed how long it took the cats to learn how to open an escape door that led to the food. Placing the animals in the same cage again and again, Thorndike found that the cats would repeat behaviors that worked and would escape more and more quickly with successive trials. Thorndike thereafter proposed the law of effect, which states that behaviors that are followed by a positive outcome are repeated, while those followed by a negative outcome or none at all are extinguished.

In 1906 Russian physiologist Ivan Pavlov - who had won a Nobel Prize two years earlier for his studies of digestion - stumbled onto one of the most important principles of learning and behavior. Pavlov was investigating the digestive process in dogs by putting food in their mouths and measuring the flow of saliva. He found that after repeated testing, the dogs would salivate in anticipation of the food, even before he put it in their mouth. He soon discovered that if he rang a bell just before the food was presented each time, the dogs would eventually salivate at the mere sound of the bell. Pavlov had discovered a basic form of learning called classical conditioning (also referred to as Pavlovian conditioning) in which an organism comes to associate one stimulus with another. Later research showed that this basic process can account for how people form certain preferences and fears.

American psychologist John B. Watson believed psychologists should study observable behavior instead of speculating about a persons inner thoughts and feelings. Watsons approach, which he termed behaviorism, dominated psychology for the first half of the 20th century.

Although Thorndike and Pavlov set the stage for behaviorism, it was not until 1913 that a psychologist set forward a clear vision for behaviorist psychology. In that year John Watson, a well-known animal psychologist at Johns Hopkins University, published a landmark paper entitled Psychology as the Behaviorist View. Watson’s goal was nothing less than a complete redefinition of psychology. Psychology as the behaviorist views it. Watson wrote, is a purely objective experimental branch of natural science. Its theoretical goal is the prediction and control of behavior. Watson narrowly defined psychology as the scientific study of behavior. He urged his colleagues to abandon both introspection and speculative theories about the unconscious. Instead he stressed the importance of observing and quantifying behavior. In light of Darwins theory of evolution, he also advocated the use of animals in psychological research, convinced that the principles of behavior would generalize across all species.

American psychologist B. F. Skinner became famous for his pioneering research on learning and behavior. During his 60-year career, Skinner discovered important principles of operant conditioning, a type of learning that involves reinforcement and punishment. A strict behaviorist, Skinner believed that operant conditioning could explain even the most complex of human behaviors.

Many American psychologists were quick to adopt behaviorism, and animal laboratories were set up all over the country. Aiming to predict and control behavior, the behaviorists strategy was to vary a stimulus in the environment and observe an organisms response. They saw no need to speculate about mental processes inside the head. For example, Watson argued that thinking was simply talking within one’ self silently. He believed that thinking could be studied by recording the movement of certain muscles in the throat.

American psychologist B. F. Skinner designed an apparatus, now called a Skinner box, that allowed him to formulate important principles of animal learning. An animal placed inside the box is rewarded with a small bit of food each time it makes the desired response, such as pressing a lever or pecking a key. A device outside the box records the animals responses.

The most forceful leader of behaviorism was B. F. Skinner, an American psychologist who began studying animal learning in the 1930s. Skinner coined the term reinforcement and invented a new research apparatus called the Skinner box for use in testing animals. Based on his experiments with rats and pigeons, Skinner identified a number of basic principles of learning. He claimed that these principles explained not only the behavior of laboratory animals, but also accounted for how human beings learn new behaviors or change existing behaviors. He concluded that nearly all behavior is shaped by complex patterns of reinforcement in a persons environment, a process that he called operant conditioning (also referred to as instrumental conditioning). Skinners views on the causes of human behavior made him one of the most famous and controversial psychologists of the 20th century.

Operant conditioning, pioneered by American psychologist B. F. Skinner, is the process of shaping behavior by means of reinforcement and punishment. This illustration shows how a mouse can learn to maneuver through a maze. The mouse is rewarded with food when it reaches the first turn in the maze (A). Once the first behavior becomes ingrained, the mouse is not rewarded until it makes the second turn (B). After many times through the maze, the mouse must reach the end of the maze to receive its reward ©.

Skinner and others applied his findings to modify behavior in the workplace, the classroom, the clinic, and other settings. In World War II (1939-1945), for example, he worked for the U.S. government on a top-secret project in which he trained pigeons to guide an armed glider plane toward enemy ships. He also invented the first teaching machine, which allowed students to learn at their own pace by solving a series of problems and receiving immediate feedback. In his popular book Walden Two (1948), Skinner presented his vision of a behaviorist utopia, in which socially adaptive behaviors are maintained by rewards, or positive reinforcements. Throughout his career, Skinner held firm to his belief that psychologists should focus on the prediction and control of behavior.

Faced with a choice between psychoanalysis and behaviorism, many psychologists in the 1950s and 1960s sensed a void in psychologies conception of human nature. Freud had drawn attention to the darker forces of the unconscious, and Skinner was interested only in the effects of reinforcement on observable behavior. Humanistic psychology was born out of a desire to understand the conscious mind, free will, human dignity, and the capacity for self-reflection and growth. An alternative to psychoanalysis and behaviorism, humanistic psychology became known as the third force.

The humanistic movement was led by American psychologists Carl Rogers and Abraham Maslow. According to Rogers, all humans are born with a drive to achieve their full capacity and to behave in ways that are consistent with their true selves. Rogers, a psychotherapist, developed person-centered therapy, a nonjudgmental, nondirective approach that helped clients clarify their sense of whom they are in an effort to facilitate their own healing process. At about the same time, Maslow theorized that all people are motivated to fulfill a hierarchy of needs. At the bottom of the hierarchy are basic physiological needs, such as hunger, thirst, and sleep. Further up the hierarchy are needs for safety and security, needs for belonging and love, and esteem-related needs for status and achievement. Once these needs are met, Maslow believed, people strive for self-actualization, the ultimate state of personal fulfillment. Though, Maslow legitimately gave to a position: The musician must orchestrate within the harmonies of a symphony, an artist must paint, justly as a poet must poetize, if he is finally to be at peace with himself. What a man can be, he must be.

Swiss psychologist Jean Piaget based his early theories of intellectual development on his questioning and observation of his own children. From these and later studies, Piaget concluded that all children pass through a predictable series of cognitive stages.

From the 1920s through the 1960s, behaviorism dominated psychology in the United States. Eventually, however, psychologists began to move away from strict behaviorism. Many became increasingly interested in cognition, a term used to describe all the mental processes involved in acquiring, storing, and using knowledge. Such processes include perception, memory, thinking, problem solving, imagining, and language. This shift in emphasis toward cognition had such a profound influence on psychology that it has often been called the cognitive revolution. The psychological study of cognition became known as cognitive psychology.

One reason for psychologists renewed interest in mental processes was the invention of the computer, which provided an intriguing metaphor for the human mind. The hardware of the computer was likened to the brain, and computer programs provided a step-by-step model of how information from the environment is input, stored, and retrieved to produce a response. Based on the computer metaphor, psychologists began to formulate information-processing models of human thought and behavior.

In the 1950s American linguist Noam Chomsky proposed that the human brain is especially constructed to detect and reproduce language and that the ability to form and understand language is innate to all human beings. According to Chomsky, young children learn and apply grammatical rules and vocabulary as they are exposed to them and do not require initial formal teaching.

The pioneering work of Swiss psychologist Jean Piaget also inspired psychologists to study cognition. During the 1920s, while administering intelligence tests in schools, Piaget became interested in how children think. He designed various tasks and interview questions to reveal how children of different ages reason about time, nature, numbers, causality, morality, and other concepts. Based on his many studies, Piaget theorized that from infancy to adolescence, children advance through a predictable series of cognitive stages.

The cognitive revolution also gained momentum from developments in the study of language. Behaviorist B.F. Skinner had claimed that language is acquired according to the laws of operant conditioning, in much the same way that rats learn to press a bar for food pellets. In 1959, however, American linguist Noam Chomsky charged that Skinners account of language development was wrong. Chomsky noted that children all over the world start to speak at roughly the same age and proceed through roughly the same stages without being explicitly taught or rewarded for the effort. According to Chomsky, the human capacity for learning language is innate. He theorized that the human brain is hardwired for language as a product of evolution. By pointing to the primary importance of biological dispositions in the development of language, Chomskys theory dealt a serious blow to the behaviorist assumption that all human behaviors are formed and maintained by reinforcement.

Before psychology became established in science, it was popularly associated with extrasensory perception (ESP) and other paranormal phenomena (phenomena beyond the laws of science). Today, these topics lie outside the traditional scope of scientific psychology and fall within the domain of parapsychology. Psychologists note that thousands of studies have failed to demonstrate the existence of paranormal phenomena.

Grounded in the conviction that mind and behavior must be studied using statistical and scientific methods, but psychology has become a highly respected and socially useful discipline. Psychologists now study importantly and sensitive topics such as the similarities and differences between men and women, racial and ethnic diversity, sexual orientation, marriage and divorce, abortion, adoption, intelligence testing, sleep and sleep disorders, obesity and dieting, and the effects of psychoactive drugs such as methylphenidate (Ritalin) and fluoxetine (Prozac).

In the last few decades, researchers have made significant breakthroughs in understanding the brain, mental processes, and behavior. This section of the article provides examples of contemporary research in psychology: the plasticity of the brain and nervous system, the nature of consciousness, memory distortions, competence and rationality, genetic influences on behavior, infancy, the nature of intelligence, human motivation, prejudice and discrimination, the benefits of psychotherapy, and the psychological influences on the immune system.

Psychologists once believed that the neural circuits of the adult brain and nervous system were fully developed and no longer subject to change. Then in the 1980s and 1990s a series of provocative experiments showed that the adult brain has flexibility, or plasticity - a capacity to change as a result of usage and experience.

These experiments showed that adult rats flooded with visual stimulation formed new neural connections in the brains visual cortex, where visual signals are interpreted. Likewise, those trained to run an obstacle course formed new connections in the cerebellum, where balance and motor skills are coordinated. Similar results with birds, mice, and monkeys have confirmed the point: Experience can stimulate the growth of new connections and mold the brains neural architecture.

Once the brain reaches maturity, the number of neurons does not increase, and any neurons that are damaged are permanently disabled. But the plasticity of the brain can greatly benefit people with damage to the brain and nervous system. Organisms can compensate for loss by strengthening old neural connections and sprouting new ones. That is why people who suffer strokes are often able to recover their lost speech and motor abilities.

In 1860 German physicist Gustav Fechner theorized that if the human brain were divided into right and left halves, each side would have its own stream of consciousness. Modern medicine has actually allowed scientists to investigate this hypothesis. People who suffer from life-threatening epileptic seizures sometimes undergo a radical surgery that severs the corpus callosum, a bridge of nerve tissue that connects the right and left hemispheres of the brain. After the surgery, the two hemispheres can no longer communicate with each other.

Scientists have long considered the nature of consciousness without producing a fully satisfactory definition. In the early 20th century American philosopher and psychologist William James suggested that consciousness is a mental process involving both attention to external stimuli and short-term memory. Later scientific explorations of consciousness mostly expanded upon James work. In this article from a 1997 special issue of Scientific American, Nobel laureate Francis Crick, who helped determine the structure of a DNA, and fellow biophysicist Christof Koch explain how experiments on vision might deepen our understanding of consciousness.

Beginning in the 1960s American neurologist Roger Sperry and others tested such split-brain patients in carefully designed experiments. The researchers found that the hemispheres of these patients seemed to function independently, almost as if the subjects had two brains. In addition, they discovered that the left hemisphere was capable of speech and language, but not the right hemisphere. For example, when split-brain patients saw the image of an object flashed in their left visual field (thus sending the visual information to the right hemisphere), they were incapable of naming or describing the object. Yet they could easily point to the correct object with their left hand (which is controlled by the right hemisphere). As Sperrys colleague Michael Gazzaniga stated, Each half brain seemed to work and function outside of the conscious realm of the other.

Other psychologists interested in consciousness have examined how people are influenced without their awareness. For example, research has demonstrated that under certain conditions in the laboratory, people can be fleetingly affected by subliminal stimuli, sensory information presented so rapidly or faintly that it falls below the threshold of awareness. (Note, however, that scientists have discredited claims that people can be importantly influenced by subliminal messages in advertising, rock music, or other media.) Other evidence for influence without awareness comes from studies of people with a type of amnesia that prevents them from forming new memories. In experiments, these subjects are unable to recognize words they previously viewed in a list, but they are more likely to use those words later in an unrelated task. In fact, memory without awareness is normal, as when people come up with an idea they think is original, only later to realize that they had inadvertently borrowed it from another source.

Cognitive psychologists have often likened human memory to a computer that encodes, stores, and retrieves information. It is now clear, however, that remembering is an active process and that people construct and alters memories according to their beliefs, wishes, needs, and information received from outside sources.

Without realizing it, people sometimes create memories that are false. In one study, for example, subjects watched a slide show depicting a car accident. They saw either a STOP sign or a YIELD sign in the slides, but afterward they were asked a question about the accident that implied the presence of the other sign. Influenced by this suggestion, many subjects recalled the wrong traffic sign. In another study, people who heard a list of sleep-related words (bed, yawn) or music-related words (jazz, instruments) were often convinced moments later that they had also heard the words sleep or music - words that fit the category but were not on the list. In a third study, researchers asked college students to recall their high-school grades. Then the researchers checked those memories against the students actual transcripts. The students recalled most grades correctly, but most of the errors inflated their grades, particularly when the actual grades were low. When scientists distinguish between human beings and other animals, they point to our larger cerebral cortex (the outer part of the brain) and to our superior intellect - as seen in the abilities to acquire and store large amounts of information, solve problems, and communicate through the use of language.

In recent years, however, those studying human cognition has found that people are often less than rational and accurate in their performance. Some researchers have found that people are prone to forgetting, and worse, that memories of past events are often highly distorted. Others have observed that people often violate the rules of logic and probability when reasoning about real events, as when gamblers overestimate the odds of winning in games of chance. One reason for these mistakes is that we commonly rely on cognitive heuristics, mental shortcuts that allow us to make judgments that are quick but often in error. To understand how heuristics can lead to mistaken assumptions, imagine offering people a lottery ticket containing six numbers out of a pool of the numbers 1 through 40. If given a choice between the tickets 6-39-2-10-24-30 or 1-2-3-4-5-6, most people select the first ticket, because it has the appearance of randomness. Yet out of the 3,838,380 possible winning combinations, both sequences are equally likely.

One of the oldest debates in psychology, and in philosophy, concerns whether individual human traits and abilities are predetermined from birth or due to ones upbringing and experiences. This debate is often termed the nature-nurture debate. A strict genetic (nature) position states that people are predisposed to become sociable, smart, cheerful, or depressed according to their genetic blueprint. In contrast, a strict environmental (nurture) position says that people are shaped by parents, peers, cultural institutions, and life experiences.

Research shows that the more genetically related a person is to someone with schizophrenia, the greater the risk that person has of developing the illness. For example, children of one parent with schizophrenia have a 13 percent chance of developing the illness, whereas children of two parents with schizophrenia have a 46 percent chance of developing the disorder.

Researchers can estimate the role of genetic factors in two ways: (1) twin studies and (2) adoption studies. Twin studies compare identical twins with fraternal twins of the same sex. If identical twins (who share all the same genes) are more similar to each other on a given trait than are same-sex fraternal twins (who share only about half of the same genes), then genetic factors are assumed to influence the trait. Other studies compare identical twins who are raised together with identical twins who are separated at birth and raised in different families. If the twins raised together are more similar to each other than the twins raised apart, childhood experiences are presumed to influence the trait. Sometimes researchers conduct adoption studies, in which they compare adopted children to their biological and adoptive parents. If these children display traits that resemble those of their biological relatives more than their adoptive relatives, genetic factors are assumed to play a role in the trait.

In recent years, several twin and adoption studies have shown that genetic factors play a role in the development of intellectual abilities, temperament and personality, vocational interests, and various psychological disorders. Interestingly, however, this same research indicates that at least 50 percent of the variation in these characteristics within the population is attributable to factors in the environment. Today, most researchers agree that psychological characteristics spring from a combination of the forces of nature and nurture.

Helpless to survive on their own, newborn babies nevertheless possess a remarkable range of skills that aid in their survival. Newborns can see, hear, taste, smell, and feel pain; vision is the least developed sense at birth but improves rapidly in the first months. Crying communicates their need for food, comfort, or stimulation. Newborns also have reflexes for sucking, swallowing, grasping, and turning their head in search of their mothers nipple.

In 1890 William James described the newborns experience as one great blooming, buzzing confusion. However, with the aid of sophisticated research methods, psychologists have discovered that infants are smarter than was previously known.

A period of dramatic growth, infancy lasts from birth to around 18 months of age. Researchers have found that infants are born with certain abilities designed to aid their survival. For example, newborns show a distinct preference for human faces over other visual stimuli.

To learn about the perceptual world of infants, researchers measure infants head movements, eye movements, facial expressions, brain waves, heart rate, and respiration. Using these indicators, psychologists have found that shortly after birth. Infants show a distinct preference for the human face over other visual stimuli. Also suggesting that newborns are tuned into the face as a social object is the fact that within 72 hours of birth, they can mimic adults who purse the lips or stick out the tongue - a rudimentary form of imitation. Newborns can distinguish between their mothers voice and that of another woman. And at two weeks old, nursing infants are more attracted to the body odor of their mother and other breast-feeding females than to that of other women. Taken together, these findings show that infants are equipped at birth with certain senses and reflexes designed to aid their survival.

In 1905 French psychologist Alfred Binet and colleague Théodore Simon devised one of the first tests of general intelligence. The test sought to identify French children likely to have difficulty in school so that they could receive special education. An American version of Binets tests, the Stanford-Binet Intelligence Scale, is still used today.

In 1905 French psychologist Alfred Binet devised the first major intelligence test for the purpose of identifying slow learners in school. In doing so, Binet assumed that intelligence could be measured as a general intellectual capacity and summarized in a numerical score, or intelligence quotient (IQ). Consistently, testing has revealed that although each of us is more skilled in some areas than in others, a general intelligence underlies our more specific abilities.

Intelligence tests often play a decisive role in determining whether a person is admitted to college, graduate school, or professional school. Thousands of people take intelligence tests every year, but many psychologists and education experts question whether these tests are an accurate way of measuring who will succeed or fail in school and later in life. In this 1998 Scientific American article, psychology and education professor Robert J. Sternberg of Yale University in New Haven, Connecticut, presents evidence against conventional intelligence tests and proposes several ways to improve testing.

Today, many psychologists believe that there is more than one type of intelligence. American psychologist Howard Gardner proposed the existence of multiple intelligence. Each linked to a separate system within the brain. He theorized that there are seven types of intelligence: linguistic, logical-mathematical, spatial, musical, bodily-kinesthetic, interpersonal, and intrapersonal. American psychologist Robert Sternberg suggested a different model of intelligence, consisting of three components: analytic (school smarts, as measured in academic tests), creative (a capacity for insight), and practical (street smarts, or the ability to size up and adapt to situations). Psychologists from all branches of the discipline study the topic of motivation, an inner state that moves an organism toward the fulfillment of some goal. Over the years, different theories of motivation have been proposed. Some theories state that people are motivated by the need to satisfy physiological needs, whereas others state that people seek to maintain an optimum level of bodily arousal (not too little and not too much). Still other theories focus on the ways in which people respond to external incentives such as money, grades in school, and recognition. Motivation researchers study a wide range of topics, including hunger and obesity, sexual desire, the effects of reward and punishment, and the needs for power, achievement, social acceptance, love, and self-esteem.

In 1954 American psychologist Abraham Maslow proposed that all people are motivated to fulfill a hierarchical pyramid of needs. At the bottom of Maslows pyramids are needs essential to survival, such as the needs for food, water, and sleep. The need for safety follows these physiological needs. According to Maslow, higher-level needs become important to us only after our more basic needs are satisfied. These higher needs include the need for love and belongingness, the need for esteem, and the need for self-actualization (in Maslows theory, a state in which people realize their greatest potential).

The view that the role of sentences in inference gives a more important key to their meaning than their external relations to things in the world. The meaning of a sentence becomes its place in a network of inferences that it legitimates. Also, known as its functional role semantics, procedural semantic or conceptual role semantics. As these view bear some relation to the coherence theory of truth, and suffers from the same suspicion that divorces meaning from any clear association with things in the world.

Paradoxes rest upon the assumption that analysis is a relation with concept, then are involving entities of other sorts, such as linguistic expressions, and that in true analysis, analysand and analysandum are one and the same concept. However, these assumptions are explicit in the British philosopher George Edward Moore, but some of Moores remarks hint at a solution that a statement of an analysis is a statement partially taken about the concept involved and partly about the verbal expression used to express it. Moore is to suggest that he thinks of a solution of this sort is bound to be right, however, facts to suggest one because he cannot reveal of any way in which the analysis can be as part of the expression.

Elsewhere, the possibility clearly does set of apparent incontrovertible premises giving unacceptable or contradictory conclusions. To solve a paradox will involve showing that either these hidden flaws in the premises, or what the reasoning is erroneous, or that the apparently unacceptable conclusion can, in fact, be tolerable. Paradoxes are therefore important in philosophy, for until one is solved it shows that there is something about our reasoning and our concepts that we do not understand. Famous families of paradoxes include the semantic paradoxes and Zenos paradoxes. At the beginning of the 20th century, Russells paradox and other set-theoretic paradoxes of set theory, while the Sorites paradox has led to the investigation of the semantics of vagueness, and fuzzy logic. Paradoxes are under their other titles. Much as there is as much as a puzzle arising when someone says p but I do not believe that p. What is said is not contradictory, since (for many instances of p) both parts of it could br. true. But the person nevertheless violates one presupposition of normal practice, namely that you assert something only if you believe it: By adding that you do not believe what you just said you undo the natural significance of the original act saying it.

Furthermore, the moral philosopher and epistemologist Bernard Bolzano (1781-1848), whose logical work was based on a strong sense of there being an ontological underpinning of science and epistemology, lying in a theory of the objective entailments masking up the structure of scientific theories. His ability to challenge wisdom and come up with startling new ideas, as a Christian philosopher whether than from any position of mathematical authority, that for considerations of infinity, Bolzanos significant work was Paradoxin des Unenndlichen, written in retirement and translated into the English as Paradoxes of the Infinite. Here, Bolzano considered directly the points that had concerned Galileo - the conflicting result that seem to emerge when infinity is studied. Certainly most of the paradoxical statements encountered in the mathematical domain . . . are propositions which either immediately contain the idea of the infinite, or at least in some way or other depends upon that idea for their attempted proof.

Continuing, Bolzano looks at two possible approaches to infinity. One is simply the case of setting up a sequence of numbers, such as the whole numbers, and saying that as it cannot conceivably be said to have a last term, it is inherently infinite - not finite. It is easy enough to show that the whole numbers do not have a point at which they stop, giving a name to that last number whatever it might have been to call it ultimate. Then what’s wrong with ultimate + 1? Why is that not a whole number?

The second approach to infinity, which Bolzano ascribes in Paradoses of the Infinite to some philosophers . . . Taking this approach describe his first conception of infinity as the bad infinity. Although the German philosopher Friedrich George Hegal (1770-1831) applies the conceptual form of infinity and points that it is, rather, the basis for a substandard infinity that merely reaches toward the absolute, but never reaches it. In Paradoses of the Infinite, he calls this form of potential infinity as a variable quantity knowing no limit to its growth (a definition adopted, even by many mathematicians) . . . always growing int the infinite and never reaching it. As far as Hegel and his colleagues were concerned, using this uprush, there was no need for a real infinity beyond some unreachable absolute. Instead we deal with a variable quality that is as big as we need it to be, or often in calculus as small as we need it to be, without ever reaching the absolute, ultimate, truly infinite.

Bolzano argues, though, that there is something else, an infinity that does not have this whatever you need it to be elasticity. In fact a truly infinite quantity (for example, the length of a straight line unbounded in either direction, meaning: The magnitude of the spatial entity containing all the points determined solely by their abstractly conceivable relation to two fixed points) does not by any means need to be variable, and in an adduced example it is in fact not variable. Conversely, it is quite possible for a quantity merely capable of being taken greater than we have already taken it, and of becoming larger than any pre-assigned (finite) quantity, nevertheless to mean at all times merely finitely, which holds in particular of every numerical quantity 1, 2, 3, 4, 5.

In other words, for Bolzano there could be a true infinity that was not a variable something that was only bigger than anything you might specify. Such a true infinity was the result of joining two pints together and extending that line in both directions without stopping. And what is more, he could separate off the demands of calculus, using a finite quality without ever bothering with the slippery potential infinity. Here was both a deeper understanding of the nature of infinity and the basis on which are built in his safe infinity free calculus.

This use of the inexhaustible follows on directly from most Bolzanos criticism of the way that 4we used as a variable something that would be bigger than anything you could specify, but never quite reached the true, absolute infinity. In Paradoxes of the Infinity Bolzano points out that is possible for a quantity merely capable of becoming larger than any other one pre-assigned (finite) quantity, nevertheless to remain at all times merely finite.

Bolzano intended tis as a criticism of the way infinity was treated, but Professor Jacquette sees it instead of a way of masking use of practical applications like calculus without the need for weasel words about infinity.

By replacing 4with ¤ we do away with one of the most common requirements for infinity, but is there anything left that map out to the real world? Can we confine infinity to that pure mathematical other world, where anything, however unreal, can be constructed, and forget about it elsewhere? Surprisingly, this seems to have been the view, at least at one point in time, even of the German mathematician and founder of set-theory Georg Cantor (1845-1918), himself, whose comments in 1883, that only the finite numbers are real.

Keeping within the lines of reason, both the Cambridge mathematician and philosopher Frank Plumpton Ramsey (1903-30) and the Italian mathematician G. Peano (1858-1932) have been to distinguish logical paradoxes and that depend upon the notion of reference or truth (semantic notions), such are the postulates justifying mathematical induction. It ensures that a numerical series is closed, in the sense that nothing but zero and its successors can be numbers. In that any series satisfying a set of axioms can be conceived as the sequence of natural numbers. Candidates from set theory include the Zermelo numbers, where the empty set is zero, and the successor of each number is its unit set, and the von Neuman numbers, where each number is the set of all smaller numbers. A similar and equally fundamental complementarity exists in the relation between zero and infinity. Although the fullness of infinity is logically antithetical to the emptiness of zero, infinity can be obtained from zero with a simple mathematical operation. The division of many numbers by zero is infinity, while the multiplication of any number by zero is zero.

With the set theory developed by the German mathematician and logician Georg Cantor. From 1878 to 1807, Cantor created a theory of abstract sets of entities that eventually became a mathematical discipline. A set, as he defined it, is a collection of definite and distinguished objects in thought or perception conceived as a whole.

Cantor attempted to prove that the process of counting and the definition of integers could be placed on a solid mathematical foundation. His method was to repeatedly place the elements in one set into one-to-one correspondence with those in another. In the case of integers, Cantor showed that each integer (1, 2, 3, . . . n) could be paired with an even integer (2, 4, 6, . . . n), and, therefore, that the set of all integers was equal to the set of all even numbers.

Amazingly, Cantor discovered that some infinite sets were large than others and that infinite sets formed a hierarchy of greater infinities. After this failed attempt to save the classical view of logical foundations and internal consistency of mathematical systems, it soon became obvious that a major crack had appeared in the seemingly sold foundations of number and mathematics. Meanwhile, an impressive number of mathematicians began to see that everything from functional analysis to the theory of real numbers depended on the problematic character of number itself.

While, in the theory of probability Ramsey was the first to show how a personalised theory could be developed, based on precise behavioural notions of preference and expectation. In the philosophy of language, Ramsey was one of the first thinkers to accept a redundancy theory of truth, which hr combined with radical views of the function of many kinds of propositions. Neither generalizations nor causal propositions, nor those treating probability or ethics, describe facts, but each has a different specific function in our intellectual economy.

Ramsey advocates that of a sentence generated by taking all the sentences affirmed in a scientific theory that use some term, e.g., quark. Replacing the term by a variable, and existentially quantifying into the result. Instead of saying quarks have such-and-such properties, Ramsey postdated that the sentence as saying that there is something that has those properties. If the process is repeated, the sentence gives the topic-neutral structure of the theory, but removes any implications that we know what the term so treated denote. It leaves open the possibility of identifying the theoretical item with whatever it is that best fits the description provided. Nonetheless, it was pointed out by the Cambridge mathematician Newman that if the process is carried out for all except the logical bones of the theory, then by the Löwenheim-Skolem theorem, the result will be interpretable in any domain of sufficient cardinality, and the content of the theory may reasonably be felt to have been lost.

It seems, that the most taken of paradoxes in the foundations of set theory as discovered by Russell in 1901. Some classes have themselves as members: The class of all abstract objects, for example, is an abstract object, whereby, others do not: The class of donkeys is not itself a donkey. Now consider the class of all classes that are not members of themselves, is this class a member of itself, that, if it is, then it is not, and if it is not, then it is.

The paradox is structurally similar to easier examples, such as the paradox of the barber. Such one like a village having a barber in it, who shaves all and only the people who do not have in themselves. Who shaves the barber? If he shaves himself, then he does not, but if he does not shave himself, then he does not. The paradox is actually just a proof that there is no such barber or in other words, that the condition is inconsistent. All the same, it is no too easy to say why there is no such class as the one Russell defines. It seems that there must be some restriction on the kind of definition that are allowed to define classes and the difficulty that of finding a well-motivated principle behind any such restriction.

The French mathematician and philosopher Henri Jules Poincaré (1854-1912) believed those paradoses like those of Russell nd the barber were due to such as the predicative definitions, and therefore proposed banning them. But, it tuns out that classical mathematics required such definitions at too many points for the ban to be easily absolved. Having, in turn, as forwarded by Poincaré and Russell, was that in order to solve the logical and semantic paradoxes it would have to ban any collection (set) containing members that can only be defined by means of the collection taken as a whole. It is, effectively by all occurring principles into which have an adopting vicious regress, as to mark the definition for which involves no such failure. There is frequently room for dispute about whether regresses are benign or vicious, since the issue will hinge on whether it is necessary to reapply the procedure. The cosmological argument is an attempt to find a stopping point for what is otherwise seen as an infinite regress, and, to ban of the predicative definitions.

The investigation of questions that arise from reflection upon sciences and scientific inquiry, are such as called of a philosophy of science. Such questions include, what distinctions in the methods of science? Is there a clear demarcation between scenes and other disciplines, and how do we place such enquires as history, economics or sociology? And scientific theories probable or more in the nature of provisional conjecture? Can the be verified or falsified? What distinguished good from bad explanations? Might there be one unified since, embracing all the special science? For much of the 20th century their questions were pursued in a high abstract and logical framework it being supposed that as general logic of scientific discovery that a general logic of scientific discovery a justification might be found. However, many now take interests in a more historical, contextual and sometimes sociological approach, in which the methods and successes of a science at a particular time are regarded less in terms of universal logical principles and procedure, and more in terms of their availability to methods and paradigms as well as the social context.

In addition, to general questions of methodology, there are specific problems within particular sciences, giving subjects as biology, mathematics and physics.

The intuitive certainty that sparks aflame the dialectic awarenesses for its immediate concerns are either of the truths or by some other in an object of apprehensions, such as a concept. Awareness as such, has to its amounting quality value the place where philosophically understanding of the source of our knowledge are, however, in covering the sensible apprehension of things and pure intuition it is that which stricture sensation into the experience of things accent of its direction that orchestrates the celestial overture into measures in space and time.

The notion that determines how something is seen or evaluated of the status of law and morality especially associated with St Thomas Aquinas and the subsequent scholastic tradition. More widely, any attempt to cement the moral and legal order together with the nature of the cosmos or how the nature of human beings, for which sense it is also found in some Protestant writers, and arguably derivative from a Platonic view of ethics, and is implicit in ancient Stoicism. Law stands above and apart from the activities of human lawmaker, it constitutes an objective set of principles that can be seen true by natural light or reason, and (in religion versions of the theory) that express Gods will for creation. Non-religious versions of the theory substitute objective conditions for human flourishing as the source of constraints upon permissible actions and social arrangements. Within the natural law tradition, different views have been held about the relationship between the rule of law about God s will, for instance the Dutch philosopher Hugo Grothius (1583-1645), similarly takes upon the view that the content of natural law is independent of any will, including that of God, while the German theorist and historian Samuel von Pufendorf (1632-94) takes the opposite view, thereby facing the problem of one horn of the Euthyphro dilemma, that simply states, that its dilemma arises from whatever the source of authority is supposed to be, for in which do we care about the general good because it is good, or do we just call good things that we care about. Wherefore, by facing the problem that may be to assume of a strong form, in which it is claimed that various facts entail values, or a weaker form, from which it confines itself to holding that reason by itself is capable of discerning moral requirements that are supped of binding to all human bings regardless of their desires

Although the morality of people send the ethical amount, from which the same thing, is that there is a usage that restricts morality to systems such as that of the German philosopher and founder of ethical philosophy Immanuel Kant (1724-1804), based on notions such as duty, obligation, and principles of conduct, reserving ethics for more than the Aristotelian approach to practical reasoning based on the notion of a virtue, and generally avoiding the separation of moral considerations from other practical considerations. The scholarly issues are complex, with some writers seeing Kant as more Aristotelian and Aristotle as, ore involved in a separate sphere of responsibility and duty, than the simple contrast suggests. Some theorists see the subject in terms of a number of laws (as in the Ten Commandments). The status of these laws may be test they are the edicts of a divine lawmaker, or that they are truths of reason, knowable deductively. Other approaches to ethics (e.g., eudaimonism, situation ethics, virtue ethics) eschew general principles as much as possible, frequently disguising the great complexity of practical reasoning. For Kantian notion of the moral law is a binding requirement of the categorical imperative, and to understand whether they are equivalent at some deep level. Kants own applications of the notion are not always convincing, as for one cause of confusion in relating Kants ethics to theories such additional expressivism is that it is easy, but mistaken, to suppose that the categorical nature of the imperative means that it cannot be the expression of sentiment, but must derive from something unconditional or necessary such as the voice of reason.

For whichever reason, the mortal being makes of its presence to the future of weighing of that which one must do, or that which can be required of one. The term carries implications of that which is owed (due) to other people, or perhaps in onself. Universal duties would be owed to persons (or sentient beings) as such, whereas special duty in virtue of specific relations, such for being the child of someone, or having made someone a promise. Duty or obligation is the primary concept of deontological approaches to ethics, but is constructed in other systems out of other notions. In the system of Kant, a perfect duty is one that must be performed whatever the circumstances: Imperfect duties may have to give way to the more stringent ones. In another way, perfect duties are those that are correlative with the right to others, imperfect duties are not. Problems with the concept include the ways in which due needs to be specified (a frequent criticism of Kant is that his notion of duty is too abstract). The concept may also suggest of a regimented view of ethical life in which we are all forced conscripts in a kind of moral army, and may encourage an individualistic and antagonistic view of social relations.

The most generally accepted account of externalism and/or internalism, that this distinction is that a theory of justification is internalist if only if it requiem that all of the factors needed for a belief to be epistemologically justified for a given person be cognitively accessible to that person, internal to his cognitive perceptive, and externalist, if it allows that at least some of the justifying factors need not be thus accessible, so that thy can be external to the believers cognitively perceptive, beyond any such given relations. However, epistemologists often use the distinction between internalist and externalist theories of epistemic justification without offering any very explicit explication.

The externalist/internalist distinction has been mainly applied to theories of epistemic justification: It has also been applied in a closely related way to accounts of knowledge and in a rather different way to accounts of belief and thought contents.

The internalist requirement of cognitive accessibility can be interpreted in at least two ways: A strong version of internalism would require that the believer actually be aware of the justifying factor in order to be justified: While a weaker version would require only that he be capable of becoming aware of them by focussing his attentions appropriately, but without the need for any change of position, new information, etc. Though the phrase cognitively accessible suggests the weak interpretation, the main intuitive motivation for internalism, viz. the idea that epistemic justification requires that the believer actually have in his cognitive possession a reason for thinking that the belief is true, and would require the strong interpretation.

Perhaps, the clearest example of an internalist position would be a Foundationalist view according to which foundational beliefs pertain to immediately experienced states of mind and other beliefs are justified by standing in cognitively accessible logical or inferential relations to such foundational beliefs. Such a view could count as either a strong or a weak version of internalism, depending on whether actual awareness of the justifying elements or only the capacity to become aware of them is required. Similarly, a coherent view could also be internalist, if both the beliefs or other states with which a justification belief is required to cohere and the coherence relations themselves are reflectively accessible.

It should be carefully noticed that when internalism is construed in this way, it is neither necessary nor sufficient by itself for internalism that the justifying factors literally be internal mental states of the person in question. Not necessary, necessary, because on at least some views, e.g., a direct realist view of perception, something other than a mental state of the believer can be cognitively accessible: Not sufficient, because there are views according to which at least some mental states need not be actual (strong version) or even possible (weak version) objects of cognitive awareness. Also, on this way of drawing the distinction, a hybrid view, according to which some of the factors required for justification must be cognitively accessible while others need not and in general will not be, would count as an externalist view. Obviously too, a view that was externalist in relation to a strong version of internalism (by not requiring that the believer actually be aware of all justifying factors) could still be internalist in relation to a weak version (by requiring that he at least be capable of becoming aware of them).

The most prominent recent externalist views have been versions of reliabilism, whose requirements for justification is roughly that the belief be produced in a way or via a process that makes of objectively likely that the belief is true. What makes such a view externalist is the absence of any requirement that the person for whom the belief is justified have any sort of cognitive access to the relations of reliability in question. Lacking such access, such a person will in general have no reason for thinking that the belief is true or likely to be true, but will, on such an account, nonetheless be epistemically justified in according it. Thus such a view arguably marks a major break from the modern epistemological tradition, stemming from Descartes, which identifies epistemic justification with having a reason, perhaps even a conclusive reason for thinking that the belief is true. An epistemologist working within this tradition is likely to feel that the externalist, than offering a competing account of the same concept of epistemic justification with which the traditional epistemologist is concerned, has simply changed the subject.

The main objection to externalism rests on the intuitive certainty that the basic requirement for epistemic justification is that the acceptance of the belief in question be rational or responsible in relation to the cognitive goal of truth, which seems to require in turn that the believer actually be dialectally aware of a reason for thinking that the belief is true (or, at the very least, that such a reason be available to him). Since the satisfaction of an externalist condition is neither necessary nor sufficient for the existence of such a cognitively accessible reason, it is argued, externalism is mistaken as an account of epistemic justification. This general point has been elaborated by appeal to two sorts of putative intuitive counter-examples to externalism. The first of these challenges the necessity of belief which seem intuitively to be justified, but for which the externalist conditions are not satisfied. The standard examples in this sort are cases where beliefs are produced in some very nonstandard way, e.g., by a Cartesian demon, but nonetheless, in such a way that the subjective experience of the believer is indistinguishable from that of someone whose beliefs are produced more normally. The intuitive claim is that the believer in such a case is nonetheless epistemically justified, as much so as one whose belief is produced in a more normal way, and hence that externalist account of justification must be mistaken.

Perhaps the most striking reply to this sort of counter-example, on behalf of a cognitive process is to be assessed in normal possible worlds, i.e., in possible worlds that are actually the way our world is common-seismically believed to be, than in the world which contains the belief being judged. Since the cognitive processes employed in the Cartesian demon cases are, for which we may assume, reliable when assessed in this way, the reliabilist can agree that such beliefs are justified. The obvious, to a considerable degree of bringing out the issue of whether it is or not an adequate rationale for this construal of reliabilism, so that the reply is not merely a notional presupposition guised as having representation.

The correlative way of elaborating on the general objection to justificatory externalism challenges the sufficiency of the various externalist conditions by citing cases where those conditions are satisfied, but where the believers in question seem intuitively not to be justified. In this context, the most widely discussed examples have to do with possible occult cognitive capacities, like clairvoyance. Considering the point in application once, again, to reliabilism, the claim is that to think that he has such a cognitive power, and, perhaps, even good reasons to the contrary, is not rational or responsible and therefore not epistemically justified in accepting the belief that result from his clairvoyance, despite the fact that the Reliabilist condition is satisfied.

One sort of response to this latter sorts of objection is to bite the bullet and insist that such believers are in fact justified, dismissing the seeming intuitions to the contrary as latent internalist prejudice. A more widely adopted response attempts to impose additional conditions, usually of a roughly internalist sort, which will rule out the offending example, while stopping far of a full internalism. But, while there is little doubt that such modified versions of externalism can handle particular cases, as well enough to avoid clear intuitive implausibility, the usually problematic cases that they cannot handle, and also whether there is and clear motivation for the additional requirements other than the general internalist view of justification that externalist are committed to reject.

A view in this same general vein, one that might be described as a hybrid of internalism and externalism holds that epistemic justification requires that there is a justificatory factor that is cognitively accessible to the believer in question (though it need not be actually grasped), thus ruling out, e.g., a pure reliabilism. At the same time, however, though it must be objectively true that beliefs for which such a factor is available are likely to be true, in addition, the fact need not be in any way grasped or cognitively accessible to the believer. In effect, of the premises needed to argue that a particular belief is likely to be true, one must be accessible in a way that would satisfy at least weak internalism, the internalist will respond that this hybrid view is of no help at all in meeting the objection and has no belief nor is it held in the rational, responsible way that justification intuitively seems to require, for the believer in question, lacking one crucial premise, still has no reason at all for thinking that his belief is likely to be true.

An alternative to giving an externalist account of epistemic justification, one which may be more defensible while still accommodating many of the same motivating concerns, is to give an externalist account of knowledge directly, without relying on an intermediate account of justification. Such a view will obviously have to reject the justified true belief account of knowledge, holding instead that knowledge is true belief which satisfies the chosen externalist condition, e.g., a result of a reliable process (and perhaps, further conditions as well). This makes it possible for such a view to retain internalist account of epistemic justification, though the centrality of that concept to epistemology would obviously be seriously diminished.

Such an externalist account of knowledge can accommodate the commonsense conviction that animals, young children, and unsophisticated adults posses knowledge, though not the weaker conviction (if such a conviction does exist) that such individuals are epistemically justified in their beliefs. It is also at least less vulnerable to internalist counter-examples of the sort discussed, since the intuitions involved there pertain more clearly to justification than to knowledge. What is uncertain is what ultimate philosophical significance the resulting conception of knowledge is supposed to have. In particular, does it have any serious bearing on traditional epistemological problems and on the deepest and most troubling versions of scepticism, which seems in fact to be primarily concerned with justification, the an knowledge?`

A rather different use of the terms internalism and externalism has to do with the issue of how the content of beliefs and thoughts is determined: According to an internalist view of content, the content of such intention states depends only on the non-relational, internal properties of the individuals mind or grain, and not at all on his physical and social environment: While according to an externalist view, content is significantly affected by such external factors and suggests a view that appears of both internal and external elements is standardly classified as an external view.

As with justification and knowledge, the traditional view of content has been strongly internalist in character. The main argument for externalism derives from the philosophy of language, more specifically from the various phenomena pertaining to natural kind terms, indexicals, etc. that motivate the views that have come to be known as direct reference theories. Such phenomena seem at least to show that the belief or thought content that can be properly attributed to a person is dependant on facts about his environment -, e.g., whether he is on Earth or Twin Earth, what is fact pointing at, the classificatory criteria employed by expects in his social group, etc. - not just on what is going on internally in his mind or brain.

An objection to externalist account of content is that they seem unable to do justice to our ability to know the content of our beliefs or thought from the inside, simply by reflection. If content is depending on external factors pertaining to the environment, then knowledge of content should depend on knowledge of these factors - which will not in general be available to the person whose belief or thought is in question.

The adoption of an externalist account of mental content would seem to support an externalist account of justification, by way that if part or all of the content of a belief inaccessible to the believer, then both the justifying status of other beliefs in relation to that content and the status of that content ss justifying further beliefs will be similarly inaccessible, thus contravening the internalist requirement for justification. An internalist must insist that there are no justification relations of these sorts, that our internally associable content can either be justified or justly anything else: But such a response appears lame unless it is coupled with an attempt to show that the externalist account of content is mistaken.

For the best of all possibilities that explains inference had first been formulated by Princeton philosopher Gilber Harnam. The idea in that when we have an easy to excavate, the idea is that when we have a best explanation of some phenomenon, we are entitled to repose confidence in it simply on that account. Sometimes thought to br. the lynchpin of scientific method, the principle is not easy to formulate and has come under attack, notably since our best current explanation of something may only be the best of a bad lot. There exist cases in which the best explanation is still not all that convincing, so other considerations than pure explanation success seem to play a role.

The philosopher Bas van Fraassen (The Scientific Image, 1980) explicated further in that constructive empiricism divides science into observation statement and theory statement. It holds that the latter are capable of strict truth and falsity, but maintains that the appropriate attitude is not to believe them, but only to accept them ss best as empirically adequate. It is often regarded as a variety of pragmatism or instrumentalism, although more orthodox varieties of those position deny that theoretic statements have truth-value. A related vie is held by the German philosopher Hans Valhinger (1854-1933), who, however, thinks that we ca be sure that theoretical statements are actually false. In other words, theories are useful because they enable us to cope with what would otherwise be the unmanageable complexity of things. The doctrine bears some affinity to pragmatism, but differs in that Vaihlinger thinks that our useful theories are nevertheless really false.

Lectures published as Pragmatism, became the new name for old ways of thinking (1907) summed up Jamess original contributions to the theory called pragmatism, a term first used by the American logician C. S. Peirce. James generalized the pragmatic method, developing it from a critique of the logical basis of the sciences into a basis for the evaluation of all experience. He maintained that the meaning of ideas is found only in terms of their possible consequences. If consequences are lacking, ideas are meaningless. James contended that this is the method used by scientists to define their terms and to test their hypotheses, which, if meaningful, entail predictions. The hypotheses can be considered true if the predicted events take place. On the other hand, most metaphysical theories are meaningless, because they entail no testable predictions. Meaningful theories, James argued, are instruments for dealing with problems that arise in experience.

According to James pragmatism, then, truth is that which works. One determines what works by testing propositions in experience. In so doing, one finds that certain propositions become true. As James put it, Truth is something that happens to an idea in the process of its verification; it is not a static property. This does not mean, however, that anything can be true. The true is only the expedient in the way of our thinking, just as the right is only the expedient in the way of our behaving, James maintained. One cannot believe whatever one want to believe, because such self-centered beliefs would not work out.

James was opposed to absolute metaphysical systems and argued against doctrines that describe reality as a unified, monolithic whole. In Essays in Radical Empiricism (1912), he argued for a pluralistic universe, denying that the world can be explained in terms of an absolute force or scheme that determines the interrelations of things and events. He held that the interrelations, whether they serve to hold things together or apart, are just as real as the things themselves.

By the end of his life, James had become world-famous as a philosopher and psychologist. In both fields, he functioned more as an originator of new thought than as a founder of dogmatic schools. His pragmatic philosophy was further developed by American philosopher John Dewey and others; later studies in physics by Albert Einstein made the theories of interrelations advanced by James appear prophetic.

Nevertheless, in science a way of looking at a field, this, however, as accorded through the lines of force whose evident physical reality o of the intervening medium whereby, the task of the philosopher of science has often been posed in terms of demarcating good or scientific theories from bad, unscientific ones wherefore he property of a statement or theory that it is capable of being refuted by experience. It a proper annunciation is accredited within the philosophy falsifiability, wherein scientific theory, as opposed to unfalsifaiability and noticeably psychoanalysis and historical materialism. The philosopher of science Raimund Karl Popper (1902-1994) whose idea was that it could be a positive virtue is a scientific theory that it is bold, conjectural, and goes beyond the evidence, but that it has to be capable of facing possible refutation. If every way that things turn out is compatible with it, then it is no longer a scientific theory, but for instance, an ideology or article of faith. Popper argued that the central virtue of science, as opposed to pseudo-science, is not that it puts forward the hypotheses that are confirmed by evidence. That is, they genuinely face the possibility of test and rejection through not confirming to evidences so gathered, that is to give no accent of te extent in which it is rational to rely upon scientific theory, however, the actual picture of acceptance and rejection of scientific hypotheses is more complex than Popper suggests. As perhaps, the view that everyday attributions of intention beliefs, and, meanings to other persons proceed via tacit use of a theory that enables one to construct of these interpretations as an explanation of their doing.

The view is commonly held along with functionalism according to which psychological states are theoretical entities, identified by te network of their causes ad effects. The theory-theory has different implications, depending upon which feature of theories is being stressed. Theories may be thought of as capable of as yielding predication and explanations, as achieved by a process of theorizing as answering to empirical evidence, that its principle describable without them, as liable to be overturned by newer and better theorise, and so on. The main problem with is with our understanding of others as the outcome of a piece of theorising is the non-existence of medium, in which his theory can be couched as the chid learns simultaneously with the minds language.

Our understanding of others is not gained by the tacit use of a theory, enabling us to infer what thoughts or intentions explain their action, but by reliving the situation in their moccasins or from their point of view, not thereby understanding what they experienced and thought, and therefore expressed. Understanding others is achieved when we can ourselves deliberate as they did, and hear their words if theory are our own. The suggestion is a modern development of the verstehe, the tradition associated with the German philosopher, literary critic and historian Wilhelm Dilthey (1833-1911).

In addition, the hypnotise especially associated with the American philosopher of mind J.A. Fodor, who affirmed strongly that mental processing occurs in a language different from ones ordinary native language, but underlying and explaining our competence with it. The idea is a development of the Chomskyan notion if an innate universal grammar, it is a way of drawing three analogies between the workings of the brain or mind and those of a standard computer, since computer programs are linguistically complex sets of instruction whose execution explains the surface behaviour of the computer. As an explanation of ordinary language learning and competence the hypothecs of thought have not found universal favour. It apparently only explains ordinary representational powers by invoking innate things of the same sort, and it invites the image of the learning infant translating the language surrounding and in back into an innate language whose own powers are a mysterious biological given.

In philosophy, the doctrine that all existence is resolvable into matter or into an attribute or effect of matter. According to this doctrine, matter is the ultimate reality, and the phenomenon of consciousness is explained by physicochemical changes in the nervous system. Materialism is thus the antithesis of idealism, in which the supremacy of mind is affirmed and matter is characterized as an aspect or objectification of mind. Extreme or absolute materialism is known as materialistic monism. According to the mind-stuff theory of monism, as expounded by the British metaphysician W. K. Clifford, in his Elements of Dynamic (1879-87), matters and minds are consubstantial, each being merely an aspect of the other. Philosophical materialism is ancient and has had numerous formulations. The early Greek philosophers subscribed to a variant of materialism known as hylozoism, according to which matter and life are identical. Related to hylozoism is the doctrine of hylotheism, in which matter is held to be divine, or the existence of God is disavowed apart from matter. Cosmological materialism is a term used to characterize a materialistic interpretation of the universe.

Antireligious materialism is motivated by a spirit of hostility toward the theological dogmas of organized religion, particularly those of Christianity. Notable among the exponents of antireligious materialism was the 18th-century French philosophers Denis Diderot, Paul Henri de’Holbach, and Julien Offroy de La Mettrie. According to historical materialism, as set forth in the writings of Karl Marx, Friedrich Engels, and Vladimir Ilich Lenin, in every historical epoch the prevailing economic system by which the necessities of life are produced determines the form of societal organization and the political, religious, ethical, intellectual, and artistic history of the epoch.

In modern times philosophical materialism has been largely influenced by the doctrine of evolution and may indeed be said to have been assimilated in the wider theory of evolution. Supporters of the theory of evolution go beyond the mere antithesis or atheism of materialism and seek positively to show how the diversities and differences in creation are the result of natural as opposed to supernatural processes.

The Philosophy of Mind is the branch of philosophy that considers mental phenomena such as sensation, perception, thought, belief, desire, intention, memory, emotion, imagination, and purposeful action. These phenomena, which can be broadly grouped as thoughts and experiences, are features of human beings; many of them are also found in other animals. Philosophers are interested in the nature of each of these phenomena as well as their relationships to one another and to physical phenomena, such as motion.

Philosophers use the characteristics of inward accessibility, subjectivity, intentionality, goal-directedness, creativity and freedom, and consciousness to distinguish mental phenomena from physical phenomena.

Perhaps the most important characteristic of mental phenomena is that they are inwardly accessible, or available to us through introspection. We each know our own minds - our sensations, thoughts, memories, desires, and fantasies - in a direct sense, by internal reflection. We also know our mental states and mental events in a way that no one else can. In other words, we have privileged access to our own mental states.

Certain mental phenomena, those we generally call experiences, have a subjective nature - that is, they have certain characteristics we become aware of when we reflect. For instance, there is something it is like to feel pain, or have an itch, or see something red. These characteristics are subjective in that they are accessible to the subject of the experience, the person who has the experience, but not to others.

Other mental phenomena, which we broadly refer to as thoughts, have a characteristic philosophers call intentionality. Intentional thoughts are about other thoughts or objects, which are represented as having certain properties or for being related to one another in a certain way. The belief that California is west of Nevada, for example, is about California and Nevada and represents the former being west of the latter. Although we have privileged access to our intentional states, many of them do not seem to have a subjective nature, at least not in the way that experiences do.

A number of mental phenomena appear to be connected to one another as elements in an intelligent, goal-directed system. The system works as follows: First, our sense organs are stimulated by events in our environment; next, by virtue of these stimulations, we perceive things about the external world; finally, we use this information, as well as information we have remembered or inferred, to guide our actions in ways that further our goals. Goal-directedness seems to accompany only mental phenomena.

Another important characteristic of mind, especially of human minds, is the capacity for choice and imagination. Rather than automatically converting past influences into future actions, individual minds are capable of exhibiting creativity and freedom. For instance, we can imagine things we have not experienced and can act in ways that no one expects or could predict.

Mental phenomena are conscious, and consciousness may be the closest term we have for describing what is special about mental phenomena. Minds are sometimes referred to as consciousness, yet it is difficult to describe exactly what consciousness is. Although consciousness is closely related to inward accessibility and subjectivity, these very characteristics seem to hinder us in reaching an objective scientific understanding of it.

Although philosophers have written about mental phenomena since ancient times, the philosophy of mind did not garner much attention until the work of French philosopher René Descartes in the 17th century. Descartes work represented a turning point in thinking about mind by making a strong distinction between bodies and minds, or the physical and the mental. This duality between mind and body, known as Cartesian dualism, has posed significant problems for philosophy ever since.

Descartes believed there are two basic kinds of things in the world, a belief known as substance dualism. For Descartes, the principles of existence for these two groups of things - bodies and minds - are completely different from one another: Bodies exist by being extended in space, while minds exist by being conscious. According to Descartes, nothing can be done to give a body thought and consciousness. No matter how we shape a body or combine it with other bodies, we cannot turn the body into a mind, a thing that is conscious, because being conscious is not a way of being extended.

For Descartes, a person consists of a human body and a human mind causally interacting with one another. For example, the intentions of a human being may have caused that persons limbs to move. In this way, the mind can affect the body. In addition, the sense organs of a human being maybe affected by light, pressure, or sound, external sources, which in turn affect the brain, affecting mental states. Thus, the body may affect the mind. Exactly how mind can affect body, and vice versa, is a central issue in the philosophy of mind, and is known as the mind-body problem. According to Descartes, this interaction of mind and body is peculiarly intimate. Unlike the interaction between a pilot and his ship, the connection between mind and body more closely resembles two substances that have been thoroughly mixed together.

In response to the mind-body problem arising from Descartes theory of substance dualism, a number of philosophers have advocated various forms of substance monism, the doctrine that there is ultimately just one kind of thing in reality. In the 18th century, Irish philosopher George Berkeley claimed there were no material objects in the world, only minds and their ideas. Berkeley thought that talk about physical objects was simply a way of organizing the flow of experience. Near the turn of the 20th century, American psychologist and philosopher William James proposed another form of substance monism. James claimed that experience is the basic stuff from which both bodies and minds are constructed.

Most philosophers of mind today are substance monists of a third type: They are materialists who believe that everything in the world is basically material, or a physical object. Among materialists, there is still considerable disagreement about the status of mental properties, which are conceived as properties of bodies or brains. Materialists who are property dualists believe that mental properties are an additional kind of property or attribute, not reducible to physical properties. Property dualists have the problem of explaining how such properties can fit into the world envisaged by modern physical science, according to which there are physical explanations for all things.

Materialists who are property monists believe that there is ultimately only one type of property, although they disagree on whether or not mental properties exist in material form. Some property monists, known as reductive materialists, hold that mental properties exist simply as a subset of relatively complex and nonbasic physical properties of the brain. Reductive materialists have the problem of explaining how the physical states of the brain can be inwardly accessible and have a subjective character, as mental states do. Other property monists, known as Eliminative materialists, consider the whole category of mental properties to be a mistake. According to them, mental properties should be treated as discredited postulates of an outmoded theory. Eliminative materialism is difficult for most people to accept, since we seem to have direct knowledge of our own philosophy of mind concerns itself with a number of specialized problems. For which the mind-body problem, becomes an important note of issues, that includes, of those impounded by personal identity, immortality, and artificial intelligence, least of mention, the capacity to deal flexibly and effectively with theoretical problems, it must be doubted to whether one thing can think or enabling if one can be of thought, as equally manifested in whatever logical, theoretical, mathematical, etc., successes we achieve. Nor is there much confidence left that intelligence tests measure any such subject’s capacity to take intelligence tests, often of very specific and culturally peculiar kinds. For the question whether humans alone posses intelligence.

During much of Western history, the mind has been identified with the soul as presented in Christian Theology. According to Christianity, the soul is the source of a persons identity and is usually regarded as immaterial; thus, it is capable of enduring after the death of the body. Descartes conception of the mind as a separate, nonmaterial substance fits well with this understanding of the soul. In Descartes view, we are aware of our bodies only as the cause of sensations and other mental phenomena. Consequently our personal essence is composed more fundamentally of mind and the preservation of the mind after death would constitute our continued existence.

The mind conceived by materialist forms of substance monism does not fit as neatly with this traditional concept of the soul. With materialism, once a physical body is destroyed, nothing enduring remains. Some philosophers think that a concept of personal identity can be constructed that permits the possibility of life after death without appealing to separate immaterial substances. Following in the tradition of 17th-century British philosopher John Locke, these philosophers propose that a person consists of a stream of mental events linked by memory. These link of memory, rather than a single underlying substance, provide the unity of a single consciousness through time. Immortality is conceivable if we think of these memory links as connecting a later consciousness in heaven with an earlier one on earth.

The field of artificial intelligence also raises interesting questions for the philosophy of mind. People have designed machines that mimic or model many aspects of human intelligence, and there are robots currently in use whose behavior is described in terms of goals, beliefs, and perceptions. Such machines are capable of behavior that, were it exhibited by a human being, would surely be taken to be free and creative. As an example, in 1996 an IBM computer named Deep Blue won a chess game against Russian world champion Garry Kasparov under international match regulations. Moreover, it is possible to design robots that have some sort of privileged access to their internal states. Philosophers disagree over whether such robots truly think or simply appear to think and whether such robots should be considered to be conscious.

Philosophy, a speculative world-view which asserts that basic reality is constantly in a process of flux and change. Indeed, reality is identified with pure process. Concepts such as creativity, freedom, novelty, emergence, and growth are fundamental explanatory categories for process philosophy. This metaphysical perspective is to be contrasted with a philosophy of substance, the view that a fixed and permanent reality underlies the changing or fluctuating world of ordinary experience. Whereas substance philosophy emphasizes static being, process philosophy emphasizes dynamically becoming.

Although process philosophy is as old as the 6th-century Bc Greek philosopher, Heraclitus, renewed interest in it was stimulated in the 19th century by the theory of evolution. Key figures in the development of modern process philosophy were the British philosophers’ Herbert Spencer, Samuel Alexander, and Alfred North Whitehead, the American philosophers Charles S. Peirce and William James, and the French philosophers Henri Bergson and Pierre Teilhard de Chardin. Whiteheads Process and Reality: An Essay in Cosmology (1929) is generally considered the most important systematic expression of process philosophy.

A contemporary theology has been strongly influenced by process philosophy. The American theologian Charles Hartshorne, for instance, rather than interpreting God as an unchanging absolute, emphasizes Gods sensitive and caring relationship with the world. A personal God enters into relationships in such a way that he is affected by the relationships, and to be affected by relationships is to change. So God too is in the process of growth and development.

Neurophysiology, is the study of how nerve cells, or neurons, receive and transmit information. Two types of phenomena are involved in processing nerve signals: electrical and chemical. Electrical events propagate a signal within a neuron, and chemical processes transmit the signal from one neuron to another neuron or to a muscle cell.

The signals conveying everything that human beings sense and think, and every motion they make, follows nerve pathways in the human body as waves of ions (atoms or groups of atoms that carries electric charges). Australian physiologist Sir John Eccles discovered many of the intricacies of this electrochemical signaling process, particularly the pivotal step in which a signal is conveyed from one nerve cell to another. He shared the 1963 Nobel Prize in physiology or medicine for this work, which he described in a 1965 Scientific American article.

A neuron is a long cell that has a thick central area containing the nucleus; it also has one long process called an axon and one or more short, bushy processes called dendrites. Dendrites receive impulses from other neurons. (The exceptions are sensory neurons, such as those that transmit information about temperature or touch, in which the signal is generated by specialized receptors in the skin.) These impulses are propagated electrically along the cell membrane to the end of the axon. At the tip of the axon the signal is chemically transmitted to an adjacent neuron or muscle cell.

Like all other cells, neurons contain charged ions: potassium and sodium (positively charged) and chlorine (negatively charged). Neurons differ from other cells in that they are able to produce a nerve impulse. A neuron is polarized - that is, it has an overall negative charge inside the cell membrane because of the high concentration of chlorine ions and low concentration of potassium and sodium ions. The concentration of these same ions is exactly reversed outside the cell. This charge differential represents stored electrical energy, sometimes referred to as membrane potential or resting potential. The negative charge inside the cell is maintained by two features. The first is the selective permeability of the cell membrane, which is more permeable to potassium than sodium. The second feature is sodium pumps within the cell membrane that actively pump sodium out of the cell. When depolarization occurs, this charge differential across the membrane is reversed, and a nerve impulse is produced.

Depolarization is a rapid change in the permeability of the cell membrane. When sensory input or any other kind of stimulating current is received by the neuron, the membrane permeability is changed, allowing a sudden influx of sodium ions into the cell. The high concentration of sodium, or action potential, changes the overalls charge within the cell from negative too positively. The locals change in ion concentration triggers similar reactions along the membrane, propagating the nerve impulse. After a brief period called the refractory period, during which the ionic concentration returned to resting potential, the neuron can repeat this process.

Nerve impulses travel at different speeds, depending on the cellular composition of a neuron. Where speed of impulse is important, as in the nervous system, axons are insulated with a membranous substance called myelin. The insulation provided by myelin maintains the ionic charge over long distances. Nerve impulses are propagated at specific points along the myelin sheath; these points are called the nodes of Ranvier. Examples of myelinated axons are those in sensory nerve fibers and nerves connected to skeletal muscles. In non-militated cells, the nerve impulse is propagated more diffusely.

When the electrical signal reaches the tip of an axon, it stimulates small presynaptic vesicles in the cell. These vesicles contain chemicals called neurotransmitters, which are released into the microscopic space between neurons (the synaptic cleft). The neurotransmitters attach to specialized receptors on the surface of the adjacent neuron. This stimulus causes the adjacent cell to depolarize and propagate an action potential of its own. The duration of a stimulus from a neurotransmitter is limited by the breakdown of the chemicals in the synaptic cleft and the reuptake by the neuron that produced them. Formerly, each neuron was thought to make only one transmitter, but recent studies have shown that some cells make two or more.

Philosophy of Mind considers mental phenomena such as sensation, perception, thought, belief, desire, intention, memory, emotion, imagination, and purposeful action. These phenomena, which can be broadly grouped as thoughts and experiences, are features of human beings; many of them are also found in other animals. Philosophers are interested in the nature of each of these phenomena as well as their relationships to one another and to physical phenomena, such as motion.

In the 17th century, French philosopher René Descartes proposed that only two substances ultimately exist; mind and body. Yet, if the two are entirely distinct, as Descartes believed, how can one substance interact with the other? How, for example, is the intention of a human mind able to cause movement in the persons limbs? The issue of the interaction between mind and body is known in philosophy as the mind-body problem.

Many fields other than a philosophy share an interest in the nature of mind. In religion, the nature of mind is connected with various conceptions of the soul and the possibility of life after death. In many abstract theories of mind there is considerable overlap between philosophy and the science of psychology. Once part of philosophy, psychology split off and formed a separate branch of knowledge in the 19th century. While psychology used scientific experiments to study mental states and events, philosophy uses reasoned arguments and thought experiments in seeking to understand the concepts that underlie mental phenomena. Also influenced by philosophy of mind is the field of artificial intelligence (AI), which endeavors to develop computers that can mimic what the human mind can do. Cognitive science attempts to integrate the understanding of mind provided by philosophy, psychology, AI, and other disciplines. Finally, all of these fields benefit from the detailed understanding of the brain that has emerged through neuroscience in the late 20th century.

Philosophers use the characteristics of inward accessibility, subjectivity, intentionality, goal-directedness, creativity and freedom, and consciousness to distinguish mental phenomena from physical phenomena.

Perhaps the most important characteristic of mental phenomena is that they are inwardly accessible, or available to us through introspection. We each know our own minds - our sensations, thoughts, memories, desires, and fantasies - in a direct sense, by internal reflection. We also know our mental states and mental events in a way that no one else can. In other words, we have privileged access to our own mental states.

Certain mental phenomena, those we generally call experiences, have a subjective nature - that is, they have certain characteristics we become aware of when we reflect. For instance, there is something it is like to feel pain, or have an itch, or see something red. These characteristics are subjective in that they are accessible to the subject of the experience, the person who has the experience, but not to others.

Other mental phenomena, which we broadly refer to as thoughts, have a characteristic philosophers call intentionality. Intentional thoughts are about other thoughts or objects, which are represented as having certain properties or for being related to one another in a certain way. The belief that California is west of Nevada, for example, is about California and Nevada and represents the former for being west of the latter. Although we have privileged access to our intentional states, many of them do not seem to have a subjective nature, at least not in the way that experiences do.

A number of mental phenomena appear to be connected to one another as elements in an intelligent, goal-directed system. The system works as follows: First, our sense organs are stimulated by events in our environment; next, by virtue of these stimulations, we perceive things about the external world; finally, we use this information, as well as information we have remembered or inferred, to guide our actions in ways that further our goals. Goal-directedness seems to accompany only mental phenomena.

Another important characteristic of mind, especially of human minds, is the capacity for choice and imagination. Rather than automatically converting past influences into future actions, individual minds are capable of exhibiting creativity and freedom. For instance, we can imagine things we have not experienced and can act in ways that no one expects or could predict.

Scientists have long considered the nature of consciousness without producing a fully satisfactory definition. In the early 20th century American philosopher and psychologist William James suggested that consciousness is a mental process involving both attention to external stimuli and short-term memory. Later scientific explorations of consciousness mostly expanded upon James work. In this article from a 1997 special issue of Scientific American, Nobel laureate Francis Crick, who helped determine the structure of DNA, and fellow biophysicists Christof Koch explains how experiments on vision might deepen our understanding of consciousness.

Mental phenomena are conscious, and consciousness may be the closest term we have for describing what is special about mental phenomena. Minds are sometimes referred to as consciousness, yet it is difficult to describe exactly what consciousness is. Although consciousness is closely related to inward accessibility and subjectivity, these very characteristics seem to hinder us in reaching an objective scientific understanding of it.

Although philosophers have written about mental phenomena since ancient times, the philosophy of mind did not garner much attention until the work of French philosopher René Descartes in the 17th century. Descartes work represented a turning point in thinking about mind by making a strong distinction between bodies and minds, or the physical and the mental. This duality between mind and body, known as Cartesian dualism, has posed significant problems for philosophy ever since.

In response to the mind-body problem arising from Descartes theory of substance dualism, a number of philosophers have advocated various forms of substance monism, the doctrine that there is ultimately just one kind of thing in reality. In the 18th century, Irish philosopher George Berkeley claimed there were no material objects in the world, only minds and their ideas. Berkeley thought that talk about physical objects was simply a way of organizing the flow of experience. Near the turn of the 20th century, American psychologist and philosopher William James proposed another form of substance monism. James claimed that experience is the basic stuff from which both bodies and minds are constructed.

Most philosophers of mind today are substance monists of a third type: They are materialists who believe that everything in the world is basically material, or a physical object. Among materialists, there is still considerable disagreement about the status of mental properties, which are conceived as properties of bodies or brains. Materialists who are property dualists believe that mental properties are an additional kind of property or attribute, not reducible to physical properties. Property dualists have the problem of explaining how such properties can fit into the world envisaged by modern physical science, according to which there are physical explanations for all things.

Materialists who are property monists believe that there is ultimately only one type of property, although they disagree on whether or not mental properties exist in material form. Some property monists, known as reductive materialists, hold that mental properties exist simply as a subset of relatively complex and nonbasic physical properties of the brain. Reductive materialists have the problem of explaining how the physical states of the brain can be inwardly accessible and have a subjective character, as mental states do. Other property monists, known as Eliminative materialists, consider the whole category of mental properties to be a mistake. According to them, mental properties should be treated as discredited postulates of an outmoded theory. Eliminative materialism is difficult for most people to accept, since we seem to have direct knowledge of our own mental phenomena by introspection and because we use the general principles we understand about mental phenomena to predict and explain the behavior of others.

Philosophy of mind seeks to answer such questions as, is mind distinct from matter? Can we define what it is to be conscious, and can we give principled reasons for deciding whether other creatures are conscious, or whether machines might be made so that they are conscious? What are thinking, feeling, experience remembering? Is it useful to divide the function of the mind up, separating memory from intelligence, or rationality from sentiment, or do mental functions form an integrated whole? The dominant philosophies of mind in the current western tradition include varieties of physicalism and functionalism. Ours’ concerns itself with a number of specialized problems. In addition to the mind-body problem, important issues include those of personal identity, as well as immortality, and artificial intelligence.

During much of Western history, the mind has been identified with the soul as presented in Christian Theology. According to Christianity, the soul is the source of a persons identity and is usually regarded as immaterial; thus, it is capable of enduring after the death of the body. Descartes conception of the mind as a separate, nonmaterial substance fits well with this understanding of the soul. In Descartes view, we are aware of our bodies only as the cause of sensations and other mental phenomena. Consequently our personal essence is composed more fundamentally of mind and the preservation of the mind after death would constitute our continued existence.

The mind conceived by materialist forms of substance monism does not fit as neatly with this traditional concept of the soul. With materialism, once a physical body is destroyed, nothing enduring remains. Some philosophers think that a concept of personal identity can be constructed that permits the possibility of life after death without appealing to separate immaterial substances. Following in the tradition of 17th-century British philosopher John Locke, these philosophers propose that a person consists of a stream of mental events linked by memory. These link of memory, rather than a single underlying substance, provide the unity of a single consciousness through time. Immortality is conceivable if we think of these memory links as connecting a later consciousness in heaven with an earlier one on earth.

No simple, agreed-upon definition of consciousness exists. Attempted definitions tend to be tautological (for example, consciousness defined as awareness) or merely descriptive (for example, consciousness described as sensations, thoughts, or feelings). Despite this problem of definition, the subject of consciousness has had a remarkable history. At one time the primary subject matter of psychology, consciousness as an area of study suffered an almost total demise, later reemerging to become a topic of current interest.

Most of the philosophical discussions of consciousness arose from the mind-body issues posed by the French philosopher and mathematician René Descartes in the 17th century. Descartes asked: Is the mind, or consciousness, independent of matter? Is consciousness extended (physical) or unextended (nonphysical)? Is consciousness determinative, or is it determined? English philosophers such as John Locke equated consciousness with physical sensations and the information they provide, whereas European philosophers such as Gottfried Wilhelm Leibniz and Immanuel Kant gave a more central and active role to consciousness.

The philosopher who most directly influenced subsequent exploration of the subject of consciousness was the 19th-century German educator Johann Friedrich Herbart, who wrote that ideas had quality and intensity and that they may inhibit or facilitate one another. Thus, ideas may pass from states of reality (consciousness) to states of tendencies (unconsciousness), with the dividing line between the two states being described as the threshold of consciousness. This formulation of Herbart clearly presages the development, by the German psychologist and physiologist Gustav Theodor Fechner, of the psychophysical measurement of sensation thresholds, and the later development by Sigmund Freud of the concept of the unconscious.

The experimental analysis of consciousness dates from 1879, when the German psychologist Wilhelm Max Wundt started his research laboratory. For Wundt, the task of psychology was the study of the structure of consciousness, which extended well beyond sensations and included feelings, images, memory, attention, duration, and movement. Because early interest focused on the content and dynamics of consciousness, it is not surprising that the central methodology of such studies was introspection; that is, subjects reported on the mental contents of their own consciousness. This introspective approach was developed most fully by the American psychologist Edward Bradford Titchener at Cornell University. Setting his task as that of describing the structure of the mind, Titchener attempted to detail, from introspective self-reports, the dimensions of the elements of consciousness. For example, taste was dimensionalized into four basic categories: sweet, sour, salt, and bitter. This approach was known as structuralism.

By the 1920s, however, a remarkable revolution had occurred in psychology that was to essentially remove considerations of consciousness from psychological research for some 50 years: Behaviorism captured the field of psychology. The main initiator of this movement was the American psychologist John Broadus Watson. In a 1913 article, Watson stated, I believe that we can write a psychology and never use the terms consciousness, mental states, mind . . . imagery and the like. Psychologists then turned almost exclusively to behavior, as described in terms of stimulus and response, and consciousness was totally bypassed as a subject. A survey of eight leading introductory psychology texts published between 1930 and the 1950s found no mention of the topic of consciousness in five texts, and in two it was treated as a historical curiosity.

Both Analytic and Linguistic philosophy, are 20th-century philosophical movements, and dominate the bettermost of Britain and the United States since World War II, that aims to clarify language and analyze the concepts expressed in it. The movement has been given a variety of designations, including linguistic analysis, logical empiricism, logical positivism, Cambridge analysis, and Oxford philosophy. The last two labels are derived from the universities in England where this philosophical method has been particularly influential. Although no specific doctrines or tenets are accepted by the movement as a whole, analytic and linguistic philosophers agree that the proper activity of philosophy is clarifying language, or, as some prefer, clarifying concepts. The aim of this activity is to settle philosophical disputes and resolve philosophical problems, which, it is argued, originates in linguistic confusion.

A considerable diversity of views exists among analytic and linguistic philosophers regarding the nature of conceptual or linguistic analysis. Some have been primarily concerned with clarifying the meaning of specific words or phrases as an essential step in making philosophical assertions clear and unambiguous. Others have been more concerned with determining the general conditions that must be met for any linguistic utterance to be meaningful; their intent is to establish a criterion that will distinguish between meaningful and nonsensical sentences. Still other analysts have been interested in creating formal, symbolic languages that are mathematical in nature. Their claim is that philosophical problems can be more effectively dealt with once they are formulated in a rigorous logical language.

By contrast, many philosophers associated with the movement have focused on the analysis of ordinary, or natural, language. Difficulties arise when concepts such as time and freedom, for example, are considered apart from the linguistic context in which they normally appear. Attention to language as it is ordinarily used is the key, it is argued, to resolving many philosophical puzzles.

Many experts believe that philosophy as an intellectual discipline originated with the works of Plato, one of the most celebrated philosophers in history. The Greek thinker had an immeasurable influence on Western thought. However, Platos expression of ideas in the form of dialogues - the dialectical method, used most famously by his teacher Socrates - has led to difficulties in interpreting some of the finer points of his thoughts. The issue of what exactly Plato meant to say is addressed in the following excerpt by author R.M. Hare.

Linguistic analysis as a method of philosophy is as old as the Greeks. Several of the dialogues of Plato, for example, are specifically concerned with clarifying terms and concepts. Nevertheless, this style of philosophizing has received dramatically renewed emphasis in the 20th century. Influenced by the earlier British empirical tradition of John Locke, George Berkeley, David Hume, and John Stuart Mill and by the writings of the German mathematician and philosopher Gottlob Frége, the 20th-century English philosophers G. E. Moore and Bertrand Russell became the founders of this contemporary analytic and linguistic trend. As students together at the University of Cambridge, Moore and Russell rejected Hegelian idealism, particularly as it was reflected in the work of the English metaphysician F. H. Bradley, who held that nothing is completely real except the Absolute. In their opposition to idealism and in their commitment to the view that careful attention to language is crucial in philosophical inquiry. They set the mood and style of philosophizing for much of the 20th century English-speaking world.

For Moore, philosophy was first and foremost analysis. The philosophical task involves clarifying puzzling propositions or concepts by indicating less puzzling propositions or concepts to which the originals are held to be logically equivalent. Once this task has been completed, the truth or falsity of problematic philosophical assertions can be determined more adequately. Moore was noted for his careful analyses of such puzzling philosophical claims as time is unreal, analyses that then aided in determining the truth of such assertions.

Russell, strongly influenced by the precision of mathematics, was concerned with developing an ideal logical language that would accurately reflect the nature of the world. Complex propositions, Russell maintained, can be resolved into their simplest components, which he called atomic propositions. These propositions refer to atomic facts, the ultimate constituents of the universe. The metaphysical views based on this logical analysis of language and the insistence that meaningful propositions must correspond to facts constitute what Russell called logical atomism. His interest in the structure of language also led him to distinguish between the grammatical form of a proposition and its logical form. The statements John is good and John is tall have the same grammatical form but different logical forms. Failure to recognize this would lead one to treat the property goodness as if it were a characteristic of John in the same way that the property tallness is a characteristic of John. Such failure results in philosophical confusion.

Austrian-born philosopher Ludwig Wittgenstein was one of the most influential thinkers of the 20th century. With his fundamental work, Tractatus Logico-philosophicus, published in 1921, he became a central figure in the movement known as analytic and linguistic philosophy.

Russells work in mathematics attracted at Cambridge, the Austrian philosopher Ludwig Wittgenstein, who became a central figure in the analytic and linguistic movement. In his first major work, Tractatus Logico-philosophicus (1921, translated, 1922), in which he first presented his theory of language, Wittgenstein argued that all philosophy is a critique of language and that philosophy aims at the logical clarification of thoughts. The results of Wittgensteins analysis resembled Russells logical atomism. The world, he argued, is ultimately composed of simple facts, which it is the purpose of language to picture. To be meaningful, statements about the world must be reducible to linguistic utterances that have a structure similar to the simple facts pictured. In this early Wittgensteinian analysis, only propositions that picture facts - the propositions of science - are considered factually meaningful. Metaphysical, theological, and ethical sentences were judged to be factually meaningless.

Influenced by Russell, Wittgenstein, Ernst Mach, and others, a group of philosophers and mathematicians in Vienna in the 1920s initiated the movement known as logical positivism: Led by Moritz Schlick and Rudolf Carnap, the Vienna Circle initiated one of the most important chapters in the history of analytic and linguistic philosophy. According to the positivist, the task of philosophy is the clarification of meaning, not the discovery of new facts (the job of the scientists) or the construction of comprehensive accounts of reality (the misguided pursuit of traditional metaphysics).

The positivist divided all meaningful assertions into two classes: analytic propositions and empirically verifiable ones. Analytic propositions, which include the propositions of logic and mathematics, are statements the truth or falsity of which depended altogether on the meanings of the terms constituting the statement. An example would be the proposition two plus two equals four. The second class of meaningful propositions includes all statements about the world that can be verified, at least in principle, by sense experience. Indeed, the meaning of such propositions is identified with the empirical method of their verification. This verifiability theory of meaning, the positivist concluded, would demonstrate that scientific statements are legitimate factual claims and that metaphysical, religious, and ethical sentences are factually empties. The ideas of logical positivism were made popular in England by the publication of A.J. Ayers Language, Truth and Logic in 1936.

The positivist verifiability theory of meaning came under intense criticism by philosophers such as the Austrian-born British philosopher Karl Popper. Eventually this narrow theory of meaning yielded to a broader understanding of the nature of language. Again, an influential figure was Wittgenstein. Repudiating many of his earlier conclusions in the Tractatus, he initiated a new line of thought culminating in his posthumously published Philosophical Investigations (1953; translated, 1953). In this work, Wittgenstein argued that once attention is directed to the way language is actually used in ordinary discourse, the variety and flexibility of language become clear. Propositions do much more than simply picture facts.

This recognition led to Wittgensteins influential concept of language games. The scientist, the poet, and the theologian, for example, are involved in different language games. Moreover, the meaning of a proposition must be understood in its context, that is, in terms of the rules of the language game of which that proposition is a part. Philosophy, concluded Wittgenstein, is an attempt to resolve problems that arise as the result of linguistic confusion, and the key to the resolution of such problems is ordinary language analysis and the proper use of language.

Additional contributions within the analytic and linguistic movement include the work of the British philosophers Gilbert Ryle, John Austin, and P. F. Strawson and the American philosopher W. V. Quine. According to Ryle, the task of philosophy is to restate systematically misleading expressions in forms that are logically more accurate. He was particularly concerned with statements the grammatical form of which suggests the existence of nonexistent objects. For example, Ryle is best known for his analysis that has of a mental capacity of language, language that misleadingly suggests that the mind is an entity in the same way as the body.

Austin maintained that one of the most fruitful starting points for philosophical inquiry is attention to the extremely fine distinctions drawn in ordinary language. His analysis of language eventually led to a general theory of speech acts, that is, to a description of the variety of activities that an individual may be performing when something is uttered.

Strawson is known for his analysis of the relationship between formal logic and ordinary language. The complexity of the latter, he argued, is inadequately represented by formal logic. A variety of analytic tools, therefore, are needed in addition to logic in analyzing ordinary language.

Quine discussed the relationship between language and ontology. He argued that language systems tend to commit their users to the existence of certain things. For Quine, the justification for speaking one way rather than another is a thoroughly pragmatic one.

The commitment to language analysis as a way of pursuing philosophy has continued as a significant contemporary dimension in philosophy. A division also continues to exist between those who prefer to work with the precision and rigor of symbolic logical systems and those who prefer to analyze ordinary language. Although few contemporary philosophers maintain that all philosophical problems are linguistic, the view continues to be widely held that attention to the logical structure of language and to how language is used in everyday discourse can often aid in resolving philosophical problems.

A loose title for various philosophies that emphasize certain common themes, the individual, the experience of choice, and the absence of rational understandings of the universe, with a consequent dread or sense of absurdity i9n human life however, Existentialism is a philosophical movement or tendency, emphasizing individual existence, freedom, and choice, that influenced many diverse writers in the 19th and 20th centuries.

Because of the diversity of positions associated with existentialism, the term is impossible to define precisely. Certain themes common to virtually all existentialist writers can, however, be identified. The term itself suggests one major theme: the stress on concrete individual existence and, consequently, on subjectivity, individual freedom, and choice.

Most philosophers since Plato have held that the highest ethical good are the same for everyone; insofar as one approaches moral perfection, one resembles other morally perfect individuals. The 19th-century Danish philosopher Søren Kierkegaard, who was the first writer to call himself existential, reacted against this tradition by insisting that the highest good for the individual are to find his or her own unique vocation. As he wrote in his journal, I must find a truth that is true for me . . . the idea for which I can live or die. Other existentialist writers have echoed Kierkegaards belief that one must choose ones own way without the aid of universal, objective standards. Against the traditional view that moral choice involves an objective judgment of right and wrong, Existentialists have argued that no objective, rational basis can be found for moral decisions. The 19th-century German philosopher Friedrich Nietzsche further contended that the individual must decide which situations are to count as moral situations.

All Existentialists have followed Kierkegaard in stressing the importance of passionate individual action in deciding questions of both morality and truth. They have insisted, accordingly, that personal experience and acting on ones own convictions are essential in arriving at the truth. Thus, the understanding of a situation by someone involved in that situation is superior to that of a detached, objective observer. This emphasis on the perspective of the individual agent has also made Existentialists suspicious of systematic reasoning. Kierkegaard, Nietzsche, and other existentialist writers have been deliberately unsystematic in the exposition of their philosophies, preferring to express themselves in aphorisms, dialogues, parables, and other literary forms. Despite their antirationalist position, however, most Existentialists cannot be said to be irrationalists in the sense of denying all validity to rational thought. They have held that rational clarity is desirable wherever possible, but that the most important questions in life are not accessible to reason or science. Furthermore, they have argued that even science is not as rational as is commonly supposed. Nietzsche, for instance, asserted that the scientific assumption of an orderly universe is for the most part a useful fiction.

Perhaps the most prominent theme in existentialist writing is that of choice. Humanities primary distinction, in the view of most Existentialists, is the freedom to choose. Existentialists have held that human beings do not have a fixed nature, or essence, as other animals and plants do; each human being makes choices that create his or her own nature. In the formulation of the 20th-century French philosopher Jean-Paul Sartre, existence precedes essence. Choice is therefore central to human existence, and it is inescapable; even the refusal to choose is a choice. Freedom of choice entails commitment and responsibility. Because individuals are free to choose their own path, Existentialists have argued, they must accept the risk and responsibility of following their commitment wherever it leads.

Kierkegaard held that it is spiritually crucial to recognize that one experiences not only a fear of specific objects but also a feeling of general apprehension, which he called dread. He interpreted it as Gods way of calling each individual to make a commitment to a personally valid way of life. The word anxiety (German Angst) has a similarly crucial role in the work of the 20th-century German philosopher Martin Heidegger; anxiety leads to the individuals confrontation with nothingness and with the impossibility of finding ultimate justification for the choices he or she must make. In the philosophy of Sartre, the word nausea is used for the individuals recognition of the pure contingency of the universe, and the word anguish is used for the recognition of the total freedom of choice that confronts the individual at every moment.

Existentialism as a distinct philosophical and literary movement belongs to the 19th and 20th centuries, but elements of existentialism can be found in the thought (and life) of Socrates, in the Bible, and in the work of many premodern philosophers and writers.

The first to anticipate the major concerns of modern existentialism was the 17th-century French philosopher Blaise Pascal. Pascal rejected the rigorous rationalism of his contemporary René Descartes, asserting, in his Pensées (1670), that a systematic philosophy that presumes to explain God and humanity is a form of pride. Like later existentialist writers, he saw human life in terms of paradoxes: The human self, which combines mind and body, is itself a paradox and contradiction.

Kierkegaard, generally regarded as the founder of modern existentialism, reacted against the systematic absolute idealism of the 19th-century German philosopher Georg Wilhelm Friedrich Hegel, who claimed to have worked out a total rational understanding of humanity and history. Kierkegaard, on the contrary, stressed the ambiguity and absurdity of the human situation. The individuals response to this situation must be to live a totally committed life, and this commitment can only be understood by the individual who has made it. The individual therefore must always be prepared to defy the norms of society for the sake of the higher authority of a personally valid way of life. Kierkegaard ultimately advocated a leap of faith into a Christian way of life, which, although incomprehensible and full of risk, was the only commitment he believed could save the individual from despair.

Danish religious philosopher Søren Kierkegaard rejected the all-encompassing, analytical philosophical systems of such 19th-century thinkers as German philosopher G.W.F. Hegel. Instead, Kierkegaard focused on the choices the individual must make in all aspects of his or her life, especially the choice to maintain religious faith. In Fear and Trembling (1846; translated 1941), Kierkegaard explored the concept of faith through an examination of the biblical story of Abraham and Isaac, in which God demanded that Abraham demonstrate his faith by sacrificing his son.

One of the most controversial works of 19th-century philosophy, Thus Spake Zarathustra (1883-1885) articulated German philosopher Friedrich Nietzsches theory of the Übermensch, a term translated as Superman or Overman. The Superman was an individual who overcame what Nietzsche termed the slave morality of traditional values, and lived according to his own morality. Nietzsche also advanced his idea that God is dead, or that traditional morality was no longer relevant in peoples lives. In this passage, the sage Zarathustra came down from the mountain where he had spent the last ten years alone to preach to the people.

Nietzsche, who was not acquainted with the work of Kierkegaard, influenced subsequent existentialist thought through his criticism of traditional metaphysical and moral assumptions and through his espousal of tragic pessimism and the life-affirming individual will that opposes itself to the moral conformity of the majority. In contrast to Kierkegaard, whose attack on conventional morality led him to advocate a radically individualistic Christianity, Nietzsche proclaimed the death of God and went on to reject the entire Judeo-Christian moral tradition in favor of a heroic pagan ideal.

The modern philosophy movements of phenomenology and existentialism have been greatly influenced by the thought of German philosopher Martin Heidegger. According to Heidegger, humankind has fallen into a crisis by taking a narrow, technological approach to the world and by ignoring the larger question of existence. People, if they wish to live authentically, must broaden their perspectives. Instead of taking their existence for granted, people should view themselves as part of Being (Heideggers terms for that which underlies all existence).

Heidegger, like Pascal and Kierkegaard, reacted against an attempt to put philosophy on a conclusive rationalistic basis - in this case the phenomenology of the 20th-century German philosopher Edmund Husserl. Heidegger argued that humanity finds itself in an incomprehensible, indifferent world. Human beings can never hope to understand why they are here; instead, each individual must choose a goal and follow it with passionate conviction, aware of the certainty of death and the ultimate meaninglessness of ones life. Heidegger contributed to existentialist thought an original emphasis on being and ontology (see Metaphysics) as well as on language.

Twentieth-century French intellectual Jean-Paul Sartre helped to develop existential philosophy through his writings, novels, and plays. Much as much of Sartres’ activities that affords the use of more words than needed to express an idea it finds in his work as it is focused on the predicament bewildered upon such plexuities that the dilemma of choice is faced by free individuals and on the particular and, yet, peculiar challenge of creating meaning by acting responsibly in an indifferent world. In stating that man is condemned to be free, Sartre reminds us of the responsibility that accompanies human decisions.

Sartre first gave the term existentialism general currency by using it for his own philosophy and by becoming the leading figure of a distinct movement in France that became internationally influential after World War II. Sartres philosophy is explicitly atheistic and pessimistic; he declared that human beings require a rational basis for their lives but are unable to achieve one, and thus human life is a futile passion. Sartre nevertheless insisted that his existentialism is a form of humanism, and he strongly emphasized human freedom, choice, and responsibility. He eventually tried to reconcile these existentialist concepts with a Marxist analysis of society and history.

Although existentialist thought encompasses the uncompromising atheism of Nietzsche and Sartre and the agnosticism of Heidegger, its origin in the intensely religious philosophies of Pascal and Kierkegaard foreshadowed its profound influence on 20th-century theologies. The 20th-century German philosopher Karl Jaspers, although he rejected explicit religious doctrines, influenced a contemporary theology through his preoccupation with transcendence and the limits of human experience. The German Protestant theologians Paul Tillich and Rudolf Bultmann, the French Roman Catholic theologian Gabriel Marcel, the Russian Orthodox philosopher Nikolay Berdyayev, and the German Jewish philosopher Martin Buber inherited many of Kierkegaards concerns, especially that a personal sense of authenticity and commitment is essential to religious faith.

Renowned as one of the most important writers in world history, 19th-century Russian author Fyodor Dostoyevsky wrote psychologically intense novels which probed the motivations and moral justifications for his characters actions. Dostoyevsky commonly addressed themes such as the struggle between good and evil within the human soul and the idea of salvation through suffering. The Brothers Karamazov (1879-1880), generally considered Dostoyevskys best work, interlaces religious exploration with the story of a families violent quarrels over a woman and a disputed inheritance.

Also, Maurice Merleau-Ponty (1908-1961), the French existentialist philosopher, whose phenomenological studies of the role of the body in perception and society opened a new field of philosophical investigation. He taught at the University of Lyon, at the Sorbonne, and, after 1952, at the Collège de France. His first important work was The Structure of Comportment (1942; translated 1963), a critique of behaviorism. His major work, Phenomenology of Perception (1945; translated 1962), is a detailed study of perception, influenced by the German philosopher Edmund Husserls phenomenology and by Gestalt psychology. In it, he argues that science presupposes an original and unique perceptual relation to the world that cannot be explained or even described in scientific terms. This book can be viewed as a critique of cognitivism - the view that the working of the human mind can be understood in terms of rules or programs. It is also a telling critique of the existentialism of his contemporary, Jean-Paul Sartre, showing how human freedom is never total, as Sartre claimed, but is limited by our embodiment.

With Sartre and Simone de Beauvoir, Merleau-Ponty founded an influential postwar French journal, Les Temps Modernes. His brilliant and timely essays on art, film, politics, psychology, and religion, first published in this journal, were later collected in Sense and Nonsense (1948; translated 1964). At the time of his death, he was working on a book, The Visible and the Invisible (1964; translated 1968), arguing that the whole perceptual world has the sort of organic unity he had earlier.

A number of existentialist philosophers used literary forms to convey their thought, and existentialism has been as vital and as extensive a movement in literature as in philosophy. The 19th-century Russian novelist Fyodor Dostoyevsky is probably the greatest existentialist literary figure. In Notes from the Underground (1864), the alienated antihero rages against the optimistic assumptions of rationalist humanism. The view of human nature that emerges in this and other novels of Dostoyevsky is that it is unpredictable and perversely self-destructive; only Christian love can save humanity from itself, but such love cannot be understood philosophically. As the character Alyosha says in The Brothers Karamazov (1879-80), We must love life more than the meaning of it.

The opening lines of Russian novelist Fyodor Dostoyevskys Notes from Underground (1864) - I am a sick man . . . I am a spiteful man - are among the most famous in 19th-century literature. Published five years after his release from prison and involuntary, military service in Siberia, Notes from Underground is a sign of Dostoyevskys rejection of the radical social thinking he had embraced in his youth. The unnamed narrator is antagonistic in tone, questioning the readers sense of morality as well as the foundations of rational thinking. In this excerpt from the beginning of the novel, the narrator describes himself, derisively referring to himself as an overly conscious intellectual.

In the 20th century, the novels of the Austrian Jewish writer Franz Kafka, such as The Trial (1925; translated 1937) and The Castle (1926; translated 1930), present isolated men confronting vast, elusive, menacing bureaucracies; Kafkas themes of anxiety, guilt, and solitude reflect the influence of Kierkegaard, Dostoyevsky, and Nietzsche. The influence of Nietzsche is also discernible in the novels of the French writers André Malraux and in the plays of Sartre. The work of the French writer Albert Camus is usually associated with existentialism because of the prominence in it of such themes as the apparent absurdity and futility of life, the indifference of the universe, and the necessity of engagement in a just cause. Existentialist themes are also reflected in the theater of the absurd, notably in the plays of Samuel Beckett and Eugene Unesco. In the United States, the influence of existentialism on literature has been more indirect and diffuse, but traces of Kierkegaards thought can be found in the novels of Walker Percy and John Updike, and various existentialist themes are apparent in the work of such diverse writers as Norman Mailer, John Barth, and Arthur

The problem of defining knowledge in terms of true belief plus some favoured relation between the believer and the facts began with Platos view in the Theaetetus, that knowledge is true belief plus some logos, an epistemology is to begin of holding the Foundations of knowledge, a special branches of philosophy that addresses the philosophical problems surrounding the theory of knowledge. Epistemology is concerned with the definition of knowledge and related concepts, the sources and criteria of knowledge, the kinds of knowledge possible and the degree to which each is certain, and the exact relation among the one who knows and the object known.

Thirteenth-century Italian philosopher and theologian Saint Thomas Aquinas attempted to synthesize Christian belief with a broad range of human knowledge, embracing diverse sources such as Greek philosopher Aristotle and Islamic and Jewish scholars. His thought exerted lasting influence on the development of Christian theology and Western philosophy. Author Anthony Kenny examines the complexities of Aquinas’ concepts of substance and accident.

In the 5th century Bc, the Greek Sophists questioned the possibility of reliable and objective knowledge. Thus, a leading Sophist, Georges, argued that nothing really exists, that if anything did exist it could not be known, and that if knowledge were possible, it could not be communicated. Another prominent Sophist, Protagoras, maintained that no persons opinions can be said to be more correct than anothers, because each is the sole judge of his or her own experience. Plato, following his illustrious teacher Socrates, tried to answer the Sophists by postulating the existence of a world of unchanging and invisible forms, or ideas, about which it is possible to have exact and certain knowledge. The things one sees and touches, they maintained, are imperfect copies of the pure forms studied in mathematics and philosophy. Accordingly, only the abstract reasoning of these disciplines yields genuine knowledge, whereas reliance on sense perception produces vague and inconsistent opinions. They concluded that philosophical contemplation of the unseen world of forms is the highest goal of human life.

Aristotle followed Plato in regarding abstract knowledge as superior to any other, but disagreed with him as to the proper method of achieving it. Aristotle maintained that almost all knowledge is derived from experience. Knowledge is gained either directly, by abstracting the defining traits of a species, or indirectly, by deducing new facts from those already known, in accordance with the rules of logic. Careful observation and strict adherence to the rules of logic, which were first set down in systematic form by Aristotle, would help guard against the pitfalls the Sophists had exposed. The Stoic and Epicurean schools agreed with Aristotle that knowledge originates in sense perception, but against both Aristotle and Plato they maintained that philosophy is to be valued as a practical guide to life, rather than as an end in itself.

After many centuries of declining interest in rational and scientific knowledge, the Scholastic philosopher Saint Thomas Aquinas and other philosophers of the Middle Ages helped to restore confidence in reason and experience, blending rational methods with faith into a unified system of beliefs. Aquinas followed Aristotle in regarding perception as the starting point and logic as the intellectual procedure for arriving at reliable knowledge of nature, but he considered faith in scriptural authority as the main source of religious belief.

From the 17th to the late 19th century, the main issue in epistemology was reasoning versus sense perception in acquiring knowledge. For the rationalists, of whom the French philosopher René Descartes, the Dutch philosopher Baruch Spinoza, and the German philosopher Gottfried Wilhelm Leibniz were the leaders, the main source and final test of knowledge was deductive reasoning based on self-evident principles, or axioms. For the empiricist, beginning with the English philosophers Francis Bacon and John Locke, the main source and final test of knowledge was sense perception.

Bacon inaugurated the new era of modern science by criticizing the medieval reliance on tradition and authority and also by setting down new rules of scientific method, including the first set of rules of inductive logic ever formulated. Locke attacked the rationalist belief that the principles of knowledge are intuitively self-evident, arguing that all knowledge is derived from experience, either from experience of the external world, which stamps sensations on the mind, or from internal experience, in which the mind reflects on its own activities. Human knowledge of external physical objects, he claimed, is always subject to the errors of the senses, and he concluded that one cannot have absolutely certain knowledge of the physical world.

Irish-born philosopher and clergyman George Berkeley (1685-1753) argued that everything that human being conceived of exists as an idea in a mind, a philosophical focus which is known as idealism. Berkeley reasoned that because one cannot control ones thoughts, they must come directly from a larger mind: that of God. In this excerpt from his Treatise Concerning the Principles of Human Knowledge, written in 1710, Berkeley explained why he believed that it is impossible . . . that there should be any such thing as an outward object.

The Irish philosopher George Berkeley agreed with Locke, that knowledge comes through ideas, but he denied Lockes belief that a distinction can be made between ideas and objects. The British philosopher David Hume continued the empiricist tradition, but he did not accept Berkeleys conclusion that knowledge was of ideas only. He divided all knowledge into two kinds: knowledge of relations of ideas - that is, the knowledge found in mathematics and logic, which is exact and certain but provide no information about the world; and knowledge of matters of fact - that is, the knowledge derived from sense perception. Hume argued that most knowledge of matters of fact depends upon cause and effect, and since no logical connection exists between any given cause and its effect, one cannot hope to know any future matter of fact with certainty. Thus, the most reliable laws of science might not remain true - a conclusion that had a revolutionary impact on philosophy.

The German philosopher Immanuel Kant tried to solve the crisis precipitated by Locke and brought to a climax by Hume; his proposed solution combined elements of rationalism with elements of empiricism. He agreed with the rationalists that one can have exact and certain knowledge, but he followed the empiricist in holding that such knowledge is more informative about the structure of thought than about the world outside of thought. He distinguished three kinds of knowledge: analytical a priori, which is exact and certain but uninformative, because it makes clear only what is contained in definitions; synthetic a posteriori, which conveys information about the world learned from experience, but is subject to the errors of the senses; and synthetic a priori, which is discovered by pure intuition and is both exact and certain, for it expresses the necessary conditions that the mind imposes on all objects of experience. Mathematics and philosophy, according to Kant, provide this last. Since the time of Kant, one of the most frequently argued questions in philosophy has been whether or not such a thing as synthetic a priori knowledge really exists.

During the 19th century, the German philosopher Georg Wilhelm Friedrich Hegel revived the rationalist claim that absolutely certain knowledge of reality can be obtained by equating the processes of thought, of nature, and of history. Hegel inspired an interest in history and a historical approach to knowledge that was further emphasized by Herbert Spencer in Britain and by the German school of historicism. Spencer and the French philosopher Auguste Comte brought attention to the importance of sociology as a branch of knowledge, and both extended the principles of empiricism to the study of society.

The American school of pragmatism, founded by the philosophers Charles Sanders Peirce, William James, and John Dewey at the turn of this century, carried empiricism further by maintaining that knowledge is an instrument of action and that all beliefs should be judged by their usefulness as rules for predicting experiences.

In the early 20th century, epistemological problems were discussed thoroughly, and subtle shades of difference grew into rival schools of thought. Special attention was given to the relation between the act of perceiving something, the object directly perceived, and the thing that can be said to be known as a result of the perception. The phenomenalists contended that the objects of knowledge are the same as the objects perceived. The neorealists argued that one has direct perceptions of physical objects or parts of physical objects, rather than of ones own mental states. The critical realists took a middle position, holding that although one perceives only sensory data such as colors and sounds, these stand for physical objects and provide knowledge thereof.

A method for dealing with the problem of clarifying the relation between the act of knowing and the object known was developed by the German philosopher Edmund Husserl. He outlined an elaborate procedure that he called phenomenology, by which one is said to be able to distinguish the way things appear to be from the way one thinks they really are, thus gaining a more precise understanding of the conceptual foundations of knowledge.

Scientific knowledge reveals that scientific knowledge and method did not spring full-blown from the minds of the ancient Greeks any more than language and culture emerged fully in the minds of Homo sapiens sapient. Scientific knowledge is an extension of ordinary language into greater levels of abstraction and precision through reliance upon geometric and numerical relationships. We speculate that the seeds of the scientific imagination were planted in ancient Greece, as opposed to Chinese or Babylonian culture, partly because the social, political and an economic climate in Greece was more open because the social, political, and economic climates in Greece was more open to the pursuit of knowledge with marginal cultural utility. Another important factor was that the special character of Homeric religion allowed the Greeks to invent a conceptual framework that would prove useful in future scientific investigations, but it was only after this inheritance from Greek philosophy was wed to some essential features of Judeo-Christian beliefs about the origin of the cosmos that the paradigm for classical physics emerged.

During the second quarter of the 20th century, two schools of thought emerged, each indebted to the Austrian philosopher Ludwig Wittgenstein. The first of these schools, logical empiricism, or logical positivism, had its origins in Vienna, Austria, but it soon spread to England and the United States. The logical empiricist insisted that there is only one kind of knowledge: scientific knowledge; that any valid knowledge claim must be verifiable in experience; and hence that much that had passed for philosophy was neither true nor false but literally meaningless. Finally, following Hume and Kant, a clear distinction must be maintained between analytic and synthetic statements. The so-called verifiability criterion of meaning has undergone changes as a result of discussions among the logical empiricists themselves, as well as their critics, but has not been discarded. More recently, the sharp distinction between the Analytic and the synthetic has been attacked by a number of philosophers, chiefly by American philosopher W.V.O. Quine, whose overall approach is in the pragmatic tradition.

The latter of these recent schools of thought, generally referred to as linguistic analysis, or ordinary language philosophy, seem to break with traditional epistemology. The linguistic analysts undertake to examine the actual way key epistemological terms are used - terms such as knowledge, perception, and probability - and to formulate definitive rules for their use in order to avoid verbal confusion. British philosopher John Langshaw Austin argued, for example, that to say a statement was truly added but nothing to the statement except a promise by the speaker or writer. Austin does not consider truth a quality or property attaching to statements or utterances. However, the ruling thought is that it is only through a correct appreciation of the role and point of this language that we can come to a better conception of what the language is about, and avoid the oversimplifications and distortion we are apt to bring to its subject matter.

Linguistics is the scientific study of language. It encompasses the description of languages, the study of their origin, and the analysis of how children acquire language and how people learn languages other than their own. Linguistics is also concerned with relationships between languages and with the ways languages change over time. Linguists may study language as a thought process and seek a theory that accounts for the universal human capacity to produce and understand language. Some linguists examine language within a cultural context. By observing talk, they try to determine what a person needs to know in order to speak appropriately in different settings, such as the workplace, among friends, or among family. Other linguists focus on what happens when speakers from different language and cultural backgrounds interact. Linguists may also concentrate on how to help people learn another language, using what they know about the learners first language and about the language being acquired.

Although there are many ways of studying language, most approaches belong to one of the two main branches of linguistics: descriptive linguistics and comparative linguistics.

Descriptive linguistics is the study and analysis of spoken language. The techniques of descriptive linguistics were devised by German American anthropologist Franz Boas and American linguist and anthropologist Edward Sapir in the early 1900s to record and analyze Native American languages. Descriptive linguistics begins with what a linguist hears native speakers say. By listening to native speakers, the linguist gathered a body of data and analyzed it in order to identify distinctive sounds, called phonemes. Individual phonemes, such as /p/ and /b/, are established on the grounds that substitution of one for the other changes the meaning of a word. After identifying the entire inventory of sounds in a language, the linguist looks at how these sounds combine to create morphemes, or units of sound that carry meaning, such as the words push and bush. Morphemes may be individual words such as push; root words, such as a berry in blueberry; or prefixes (pre-in previews) and suffixes (-nesses in openness).

The linguists next step is to see how morphemes combine into sentences, obeying both the dictionary meaning of the morpheme and the grammatical rules of the sentence. In the sentence She pushed the bush, the morpheme she, a pronoun, is the subject; push, a transitive verb, is the verb the, a definite article, is the determiner; and bush, a noun, is the object. Knowing the function of the morphemes in the sentence enables the linguist to describe the grammar of the language. The scientific procedures of phonemics (finding phonemes), morphology (discovering morphemes), and syntaxes (describing the order of morphemes and their function) provided descriptive linguists with a way to write down grammars of languages never before written down or analyzed. In this way they can begin to study and understand these languages.

Comparative linguistics is the study and analysis, by means of written records, of the origins and relatedness of different languages. In 1786 Sir William Jones, a British scholar, asserted that Sanskrit, Greek, and Latin was related to one another and had descended from a common source. He based this assertion on observations of similarities in sounds and meanings among the three languages. For example, the Sanskrit word bhratar for brother resembles the Latin word frater, the Greek word phrater, (and the English word brother).

Other scholars went on to compare Icelandic with Scandinavian languages, and Germanic languages with Sanskrit, Greek, and Latin. The correspondences among languages, known as genetic relationships, came to be represented on what comparative linguists refer to as family trees. Family trees established by comparative linguists include the Indo-European, relating Sanskrit, Greek, Latin, German, English, and other Asian and European languages; the Algonquian, relating Fox, Cree, Menomini, Ojibwa, and other Native North American languages; and the Bantu, relating Swahili, Xhosa, Zulu, Kikuyu, and other African languages.

Comparative linguists also look for similarities in the way words are formed in different languages. Latin and English, for example, change the form of a word to express different meanings, as when the English verb goes interchangeably to go and gone, only to express a past action. Chinese, on the other hand, has no such inflected forms; the verb remains the same while other words indicate the time (as, in go store tomorrow). In Swahili, prefixes, suffixes, and infixes (additions in the body of the word) combine with a root word to change its meaning. For example, a single word might expressibly go when something was done, by whom, to whom, and in what manner.

Some comparative linguists reconstruct hypothetical ancestral languages known as proto-languages, which they use to demonstrate relatedness among contemporary languages. A proto-language is not intended to depict a real language, however, and does not represent the speech of ancestors of people speaking modern languages. Unfortunately, some groups have mistakenly used such reconstructions in efforts to demonstrate the ancestral homeland of those people.

Comparative linguists have suggested that certain basic words in a language do not change over time, because people are reluctant to introduce new words for such constants as arm, eye, or mother. These words are termed culture free. By comparing lists of culture-free words in languages within a family, linguists can derive the percentage of related words and use a formula to figure out when the languages separated from one another.

By the 1960s comparativists were no longer satisfied with focusing on origins, migrations, and the family tree method. They challenged as unrealistic the notion that an earlier language could remain sufficiently isolated for other languages to be derived exclusively from it over a period of time. Today comparativists seek to understand the more complicated reality of language history, taking language contact into account. They are concerned with universal characteristics of language and with comparisons of grammars and structures.

The field of linguistics both borrows from and lends its own theories and methods to other disciplines. The many subfields of linguistics have expanded our understanding of languages. Linguistic theories and methods are also used in other fields of study. These overlapping interests have led to the creation of several cross-disciplinary fields.

Socio-linguistics is the study of patterns and variations in language within a society or community. It focuses on the way people use language to express social class, group status, gender, or ethnicity, and it looks at how they make choices about the form of language they use. It also examines the way people use language to negotiate their role in society and to achieve positions of power. For example, sociolinguistic studies have found that the way a New Yorker pronounces the phoneme /r/ in an expression such as fourth floor can indicate the persons social class. According to one study, people aspiring to move from the lower middle classes to the upper middle class attach prestige to pronouncing the /r/. Sometimes they even overcorrect their speech, pronouncing a /r/ where those whom they wish to copy may not.

Some sociolinguists believe that analyzing such variables as the use of a particular phoneme can predict the direction of language change. Change, they say, moves toward the variable associated with power, prestige, or other quality having high social value. Other sociolinguists focus on what happens when speakers of different languages interact. This approach to language change emphasizes the way languages mix rather than the direction of change within a community. The goal of Sociolinguistics is to understand communicative competence - what people need to know to use the appropriate language for a given social setting.

Psycholinguistics merge the fields of psychology and linguistics to study how people process language and how language use is related to underlying mental processes. Studies of childrens language acquisition and of second-language acquisition are psycholinguistic in nature. Psycholinguists work to develop models for how language is processed and understood, using evidence from studies of what happens when these processes go awry. They also study language disorders such as aphasia (impairment of the ability to use or comprehend words) and dyslexia (impairment of the ability to make out written language).

Computational linguistics involves the use of computers to compile linguistic data, analyze languages, translate from one language to another, and develop and test models of language processing. Linguists use computers and large samples of actual language to analyze the relatedness and the structure of languages and to look for patterns and similarities. Computers also aid in stylistic studies, information retrieval, various forms of textual analysis, and the construction of dictionaries and concordances. Applying computers to language studies has resulted in machine translation systems and machines that recognize and produce speech and text. Such machines facilitate communication with humans, including those who are perceptually or linguistically impaired.

Applied linguistics employs linguistic theory and methods in teaching and in research on learning a second language. Linguists look at the errors people make as they learn another language and at their strategies for communicating in the new language at different degrees of competence. In seeking to understand what happens in the mind of the learner, applied linguists recognize that motivation, attitude, learning style, and personality affect how well a person learns another language.

Anthropological linguistics, also known as linguistic anthropology, uses linguistic approaches to analyze culture. Anthropological linguists examine the relationship between a culture and its language. The way cultures and languages have changed over time, and how different cultures and languages are related to one another. For example, the present English use of family and given names arose in the late 13th and early 14th centuries when the laws concerning registration, tenure, and inheritance of property were changed.

Philosophical linguistics examines the philosophy of language. Philosophers of language search for the grammatical principles and tendencies that all human languages share. Among the concerns of linguistic philosophers is the range of possible word order combinations throughout the world. One finding is that 95 percent of the worlds languages use a subject-verb-object (SVO) order as English does (She pushed the bush.). Only 5 percent use a subject-object-verb (SOV) order or verb-subject-object (VSO) order.

Neurolinguistics are the study of how language is processed and represented in the brain. Neurolinguists seek to identify the parts of the brain involved with the production and understanding of language and to determine where the components of language (phonemes, morphemes, and structure or syntax) are stored. In doing so, they make use of techniques for analyzing the structure of the brain and the effects of brain damage on language.

Speculation about language goes back thousands of years. Ancient Greek philosophers speculated on the origins of language and the relationship between objects and their names. They also discussed the rules that govern language, or grammar, and by the 3rd century Bc they had begun grouping words into parts of speech and devising names for different forms of verbs and nouns.

In India religion provided the motivation for the study of language nearly 2500 years ago. Hindu priests noted that the language they spoke had changed since the compilation of their ancient sacred texts, the Vedas, starting about 1000 Bc. They believed that for certain religious ceremonies based upon the Vedas to succeed, they needed to reproduce the language of the Vedas precisely. Panini, an Indian grammarian who lived about 400 Bc, produced the earliest work describing the rules of Sanskrit, the ancient language of India.

The Romans used Greek grammars as models for their own, adding commentary on Latin style and usage. Statesman and orator Marcus Tullius Cicero wrote on rhetoric and style in the 1st century Bc. Later grammarians Aelius Donatus (4th century AD) and Priscian (6th century AD) produced detailed Latin grammars. Roman works served as textbooks and standards for the study of language for more than 1000 years.

It was not until the end of the 18th century that language was researched and studied in a scientific way. During the 17th and 18th centuries, modern languages, such as French and English, replaced Latin as the means of universal communication in the West. This occurrence, along with developments in printing, meant that many more texts became available. At about this time, the study of phonetics, or the sounds of a language, began. Such investigations led to comparisons of sounds in different languages; in the late 18th century the observation of correspondences among Sanskrit, Latin, and Greek gave birth to the field of Indo-European linguistics.

During the 19th century, European linguists focused on philology, or the historical analysis and comparison of languages. They studied written texts and looked for changes over time or for relationships between one language and another.

American linguist, writer, teacher, and political activist Noam Chomsky is considered the founder of transformational-generative linguistic analysis, which revolutionized the field of linguistics. This system of linguistics treats grammar as a theory of language - that is, Chomsky believes that in addition to the rules of grammar specific to individual languages, there are universal rules common to all languages that indicate that the ability to form and understand language is innate to all human beings. Chomsky also is well known for his political activism - he opposed United States involvement in Vietnam in the 1960s and 1970s and has written various books and articles and delivered many lectures in an attempt to educate and empower people on various political and social issues.

In the early 20th century, linguistics expanded to include the study of unwritten languages. In the United States linguists and anthropologists began to study the rapidly disappearing spoken languages of Native North Americans. Because many of these languages were unwritten, researchers could not use historical analysis in their studies. In their pioneering research on these languages, anthropologists Franz Boas and Edward Sapir developed the techniques of descriptive linguistics and theorized on the ways in which language shapes our perceptions of the world.

An important outgrowth of descriptive linguistics is a theory known as structuralism, which assumes that language is a system with a highly organized structure. Structuralism began with publication of the work of Swiss linguist Ferdinand de Saussure in Cours de linguistique générale (1916; Course in General Linguistics, 1959). This work, compiled by Saussures students after his death, is considered the foundation of the modern field of linguistics. Saussure made a distinction between actual speech, or spoken language, and the knowledge underlying speech that speakers share about what is grammatical. Speech, he said, represents instances of grammar, and the linguist’s task is to find the underlying rules of a particular language from examples found in speech. To the Structuralists, grammar is a set of relationships that account for speech, rather than a set of instances of speech, as it is to the descriptivist.

Once linguists began to study language as a set of abstract rules that somehow account for speech, other scholars began to take an interest in the field. They drew analogies between language and other forms of human behavior, based on the belief that a shared structure underlies many aspects of a culture. Anthropologists, for example, became interested in a Structuralists approach to the interpretation of kinship systems and analysis of myth and religion. American linguist Leonard Bloomfield promoted structuralism in the United States.

Saussures ideas also influenced European linguistics, most notably in France and Czechoslovakia (now the Czech Republic). In 1926 Czech linguist Vilem Mathesius founded the Linguistic Circle of Prague, a group that expanded the focus of the field to include the context of language use. The Prague circle developed the field of phonology, or the study of sounds, and demonstrated that universal features of sounds in the languages of the world interrelate in a systematic way. Linguistic analysis, they said, should focus on the distinctiveness of sounds rather than on the ways they combine. Where descriptivists tried to locate and describe individual phonemes, such as /b/ and /p/, the Prague linguists stressed the features of these phonemes and their interrelationships in different languages. In English, for example, the voice distinguishes between the similar sounds of /b/ and /p/, but these are not distinct phonemes in a number of other languages. An Arabic speaker might pronounce the cities Pompei and Bombay the same way.

As linguistics developed in the 20th century, the notion became prevalent that language is more than speech - specifically, that it is an abstract system of interrelationships shared by members of a speech community. Structural linguistics led linguists to look at the rules and the patterns of behavior shared by such communities. Whereas structural linguists saw the basis of language in the social structure, other linguists looked at language as a mental process.

The 1957 publication of Syntactic Structures by American linguist Noam Chomsky initiated what many view as a scientific revolution in linguistics. Chomsky sought a theory that would account for both linguistic structure and the creativity of language - the fact that we can create entirely original sentences and understand sentences never before uttered. He proposed that all people have an innate ability to acquire language. The task of the linguist, he claimed, is to describe this universal human ability, known as language competence, with a grammar from which the grammars of all languages could be derived. The linguist would develop this grammar by looking at the rules children use in hearing and speaking their first language. He termed the resulting model, or grammar, a transformational-generative grammar, referring to the transformations (or rules) that generate (or account for) language. Certain rules, Chomsky asserted, are shared by all languages and form part of a universal grammar, while others are language specific and associated with particular speech communities. Since the 1960s much of the development in the field of linguistics has been a reaction to or against Chomskys theories.

At the end of the 20th century, linguists used the term grammar primarily to refer to a subconscious linguistic system that enables people to produce and comprehend an unlimited number of utterances. Grammar thus accounts for our linguistic competence. Observations about the actual language we use, or language performance, are used to theorize about this invisible mechanism known as grammar.

The orientation toward the scientific study of language led by Chomsky has had an impact on nongenerative linguists as well. Comparative and historically oriented linguists are looking for the various ways linguistic universals show up in individual languages. Psycholinguists, interested in language acquisition, are investigating the notion that an ideal speaker-hearer is the origin of the acquisition process. Sociolinguists are examining the rules that underlie the choice of language variants, or codes, and allow for switching from one code to another. Some linguists are studying language performance - the way people use language - see how it reveals a cognitive ability shared by all human beings. Others seek to understand animal communication within such a framework. What mental processes enable chimpanzees to make signs and communicate with one another and how do these processes differ from those of humans?

A written bibliographic note in gratification To Ludwig Wittgenstein (1889-1951), an Austrian-British philosopher, who was one of the most influential thinkers of the 20th century, particularly noted for his contribution to the movement known as analytic and linguistic philosophy.

Born in Vienna on April 26, 1889, Wittgenstein was raised in a wealthy and cultured family. After attending schools in Linz and Berlin, he went to England to study engineering at the University of Manchester. His interest in pure mathematics led him to Trinity College, University of Cambridge, to study with Bertrand Russell. There he turned his attention to philosophy. By 1918 Wittgenstein had completed his Tractatus Logico-philosophicus (1921; translated 1922), a work he then believed provided the final solution to philosophical problems. Subsequently, he turned from philosophy and for several years taught elementary school in an Austrian village. In 1929 he returned to Cambridge to resume his work in philosophy and was appointed to the faculty of Trinity College. Soon he began to reject certain conclusions of the Tractatus and to develop the position reflected in his Philosophical Investigations (pub. posthumously 1953; translated 1953). Wittgenstein retired in 1947; he died in Cambridge on April 29, 1951. A sensitive, intense man who often sought solitude and was frequently depressed, Wittgenstein abhorred pretense and was noted for his simple style of life and dress. The philosopher was forceful and confident in personality, however, and he exerted considerable influence on those with whom he came in contact.

Wittgensteins’ philosophical life may be divided into two distinct phases: an early period, represented by the Tractatus, and a later period, represented by the Philosophical Investigations. Throughout most of his life, however, Wittgenstein consistently viewed philosophy as linguistic or conceptual analysis. In the Tractatus he argued that philosophy aims at the logical clarification of thoughts. In the Philosophical Investigations, however, he maintained that philosophy is a battle against the bewitchment of our intelligence by means of language.

Language, Wittgenstein argued in the Tractatus, is composed of complex propositions that can be analyzed into fewer complex propositions until one arrives at simple or elementary propositions. Correspondingly, the world is composed of complex facts that can be analyzed into fewer complex facts until one arrives at simple, or atomic, facts. The world is the totality of these facts. According to Wittgensteins picture theory of meaning, it is the nature of elementary propositions logically to picture atomic facts, or states of affairs. He claimed that the nature of language required elementary propositions, and his theory of meaning required that there be atomic facts pictured by the elementary propositions. On this analysis, only propositions that picture facts - the propositions of science - are considered cognitively meaningfully. Metaphysical and ethical statements are not meaningful assertions. The logical positivist associated with the Vienna Circle were greatly influenced by this conclusion.

Wittgenstein came to believe, however, that the narrow view of language reflected in the Tractatus was mistaken. In the Philosophical Investigations he argued that if one actually looks to see how language is used, the variety of linguistic usage becomes clear. Words are like tools, and just as tools serve different functions, so linguistic expressions serve many functions. Although some propositions are used to picture facts, others are used to command, question, pray, thank, curse, and so on. This recognition of linguistic flexibility and variety led to Wittgensteins concept of a language game and to the conclusion that people play different language games. The scientist, for example, is involved in a different language game than the theologian. Moreover, the meaning of a proposition must be understood in terms of its context, that is, in terms of the rules of the game of which that proposition is a part. The key to the resolution of philosophical puzzles is the therapeutic process of examining and describing language in use.

Analytic and Linguistic Philosophy, is a product out of the 20th-century philosophical movement, and dominant in Britain and the United States since World War II, that aims to clarify language and analyze the concepts expressed in it. The movement has been given a variety of designations, including linguistic analysis, logical empiricism, logical positivism, Cambridge analysis, and Oxford philosophy. The last two labels are derived from the universities in England where this philosophical method has been particularly influential. Although no specific doctrines or tenets are accepted by the movement as a whole, analytic and linguistic philosophers agree that the proper activity of philosophy is clarifying language, or, as some prefer, clarifying concepts. The aim of this activity is to settle philosophical disputes and resolve philosophical problems, which, it is argued, originates in linguistic confusion.

A considerable diversity of views exists among analytic and linguistic philosophers regarding the nature of conceptual or linguistic analysis. Some have been primarily concerned with clarifying the meaning of specific words or phrases as an essential step in making philosophical assertions clear and unambiguous. Others have been more concerned with determining the general conditions that must be met for any linguistic utterance to be meaningful; their intent is to establish a criterion that will distinguish between meaningful and nonsensical sentences. Still other analysts have been interested in creating formal, symbolic languages that are mathematical in nature. Their claim is that philosophical problems can be more effectively dealt with once they are formulated in a rigorous logical language.

By contrast, many philosophers associated with the movement have focused on the analysis of ordinary, or natural, language. Difficulties arise when concepts such as time and freedom, for example, are considered apart from the linguistic context in which they normally appear. Attention to language as it is ordinarily used is the key, it is argued, to resolving many philosophical puzzles.

Linguistic analysis as a method of philosophy is as old as the Greeks. Several of the dialogues of Plato, for example, are specifically concerned with clarifying terms and concepts. Nevertheless, this style of philosophizing has received dramatically renewed emphasis in the 20th century. Influenced by the earlier British empirical tradition of John Locke, George Berkeley, David Hume, and John Stuart Mill and by the writings of the German mathematician and philosopher Gottlob Frége, the 20th-century English philosophers G. E. Moore and Bertrand Russell became the founders of this contemporary analytic and linguistic trend. As students together at the University of Cambridge, Moore and Russell rejected Hegelian idealism, particularly as it was reflected in the work of the English metaphysician F. H. Bradley, who held that nothing is completely real except the Absolute. In their opposition to idealism and in their commitment to the view that careful attention to language is crucial in philosophical inquiry. They set the mood and style of philosophizing for much of the 20th century English-speaking world.

For Moore, philosophy was first and foremost analysis. The philosophical task involves clarifying puzzling propositions or concepts by indicating fewer puzzling propositions or concepts to which the originals are held to be logically equivalent. Once this task has been completed, the truth or falsity of problematic philosophical assertions can be determined more adequately. Moore was noted for his careful analyses of such puzzling philosophical claims as time is unreal, analyses that then aided in determining the truth of such assertions.

Russell, strongly influenced by the precision of mathematics, was concerned with developing an ideal logical language that would accurately reflect the nature of the world. Complex propositions, Russell maintained, can be resolved into their simplest components, which he called atomic propositions. These propositions refer to atomic facts, the ultimate constituents of the universe. The metaphysical views based on this logical analysis of language and the insistence that meaningful propositions must correspond to facts constitute what Russell called logical atomism. His interest in the structure of language also led him to distinguish between the grammatical form of a proposition and its logical form. The statements John is good and John is tall have the same grammatical form but different logical forms. Failure to recognize this would lead one to treat the property goodness as if it were a characteristic of John in the same way that the property tallness is a characteristic of John. Such failure results in philosophical confusion.

Russells work in mathematics attracted to Cambridge. The Austrian philosopher Ludwig Wittgenstein, who became a central figure in the analytic and linguistic movement. In his first major work, Tractatus Logico-philosophicus (1921; translated 1922), in which he first presented his theory of language, Wittgenstein argued that all philosophy is a critique of language and that philosophy aims at the logical clarification of thoughts. The results of Wittgensteins analysis resembled Russells logical atomism. The world, he argued, is ultimately composed of simple facts, which it is the purpose of language to picture. To be meaningful, statements about the world must be reducible to linguistic utterances that have a structure similar to the simple facts pictured. In this early Wittgensteinian analysis, only propositions that picture facts - the propositions of science - are considered factually meaningful. Metaphysical, theological, and ethical sentences were judged to be factually meaningless continues to exist between.

Influenced by Russell, Wittgenstein, Ernst Mach, and others, a group of philosophers and mathematicians in Vienna in the 1920s initiated the movement known as logical positivism. Led by Moritz Schlick and Rudolf Carnap, the Vienna Circle initiated one of the most important chapters in the history of analytic and linguistic philosophy. According to the positivist, the task of philosophy is the clarification of meaning, not the discovery of new facts (the job of the scientists) or the construction of comprehensive accounts of reality (the misguided pursuit of traditional metaphysics).

The positivist divided all meaningful assertions into two classes: analytic propositions and empirically verifiable ones. Analytic propositions, which include the propositions of logic and mathematics, are statements the truth or falsity of which depend together on the meanings of the terms constituting the statement. An example would be the proposition two plus two equals four. The second class of meaningful propositions includes all statements about the world that can be verified, at least in principle, by sense experience. Indeed, the meaning of such propositions is identified with the empirical method of their verification. This verifiability theory of meaning, the positivist concluded, would demonstrate that scientific statements are legitimate factual claims and that metaphysical, religious, and ethical sentences are factually empties. The ideas of logical positivism were made popular in England by the publication of A.J. Ayers Language, Truth and Logic in 1936.

The positivist verifiability theory of meaning came under intense criticism by philosophers such as the Austrian-born British philosopher Karl Popper. Eventually this narrow theory of meaning yielded to a broader understanding of the nature of language. Again, an influential figure was Wittgenstein. Repudiating many of his earlier conclusions in the Tractatus, he initiated a new line of thought culminating in his posthumously published Philosophical Investigations (1953; translated 1953). In this work, Wittgenstein argued that once attention is directed to the way language is actually used in ordinary discourse, the variety and flexibility of language become clear. Propositions do much more than simply picture facts.

This recognition led to Wittgensteins influential concept of language games. The scientist, the poet, and the theologian, for example, are involved in different language games. Moreover, the meaning of a proposition must be understood in its context, that is, in terms of the rules of the language game of which that proposition is a part. Philosophy, concluded Wittgenstein, is an attempt to resolve problems that arise as the result of linguistic confusion, and the key to the resolution of such problems is ordinary language analysis and the proper use of language.

Additional contributions within the analytic and linguistic movement include the work of the British philosophers Gilbert Ryle, John Austin, and P. F. Strawson and the American philosopher W. V. Quine. According to Ryle, the task of philosophy is to restate systematically misleading expressions in forms that are logically more accurate. He was particularly concerned with statements the grammatical form of which suggests the existence of nonexistent objects. For example, Ryle is best known for his analysis of mentalistic language, language that misleadingly suggests that the mind is an entity in the same way as the body.

Austin maintained that one of the most fruitful starting points for philosophical inquiry is attention to the extremely fine distinctions drawn in ordinary language. His analysis of language eventually led to a general theory of speech acts, that is, to a description of the variety of activities that an individual may be performing when something is uttered.

Strawson is known for his analysis of the relationship between formal logic and ordinary language. The complexity of the latter, he argued, is inadequately represented by formal logic. A variety of analytic tools, therefore, are needed in addition to logic in analyzing ordinary language.

Quine discussed the relationship between language and ontology. He argued that language systems tend to commit their users to the existence of certain things. For Quine, the justification for speaking one way rather than another is a thoroughly pragmatic one.

The commitment to language analysis as a way of pursuing philosophy has continued as a significant contemporary dimension in philosophy. A division also those who prefer to work with the precision and rigor of symbolic logical systems and those who prefer to analyze ordinary language. Although few contemporary philosophers maintain that all philosophical problems are linguistic, the view continues to be widely held that attention to the logical structure of language and to how language is used in everyday discourse can often aid in resolving philosophical problems

Are terms of logical calculus are also called a formal language, and a logical system? A system in which explicit rules are provided to determining (1) which are the expressions of the system (2) which sequence of expressions count as well formed (well-forced formulae) (3) which sequence would count ss proofs. A system may include axioms for which leaves terminate a proof, however, it shows of the prepositional calculus and the predicated calculus.

Its most immediate of issues surrounding certainty are especially connected with those concerning scepticism. Although Greek scepticism entered on the value of enquiry and questioning, scepticism is now the denial that knowledge or even rational belief is possible, either about some specific subject-matter, e.g., ethics, or in any area whatsoever. Classical scepticism, springs from the observation that the best method in some area seems to fall short of giving us contact with the truth, e.g., there is a gulf between appearances and reality, it frequently cites the conflicting judgements that our methods deliver, with the result that questions of truth become undefinable. In classic thought the various examples of this conflict were systemized in the tropes of Aenesidemus. So that, the scepticism of Pyrrho and the new Academy was a system of argument and inasmuch as opposing dogmatism, and, particularly the philosophical system building of the Stoics.

As it has come down to us, particularly in the writings of Sextus Empiricus, its method was typically to cite reasons for finding our issue undesirable (sceptics devoted particular energy to undermining the Stoics conception of some truths as delivered by direct apprehension or some katalepsis). As a result the sceptic concludes eposhé, or the suspension of belief, and then go on to celebrate a way of life whose object was ataraxia, or the tranquillity resulting from suspension of belief.

Fixed by its will for and of itself, the mere mitigated scepticism which accepts every day or commonsense belief, is that, not the delivery of reason, but as due more to custom and habit. Nonetheless, it is self-satisfied at the proper time, however, the power of reason to give us much more. Mitigated scepticism is thus closer to the attitude fostered by the accentuations from Pyrrho through to Sextus Expiricus. Despite the fact that the phrase Cartesian scepticism is sometimes used. Descartes himself was not a sceptic, however, in the method of doubt uses a sceptical scenario in order to begin the process of finding a general distinction to mark its point of knowledge. Descartes trusts in categories of clear and distinct ideas, not far removed from the phantasiá kataleptikê of the Stoics.

For many sceptics had traditionally held that knowledge requires certainty, artistry. And, of course, they claim that certain knowledge is not possible. In part, nonetheless, of the principle that every effect its a consequence of an antecedent cause or causes. For causality to be true it is not necessary for an effect to be predictable as the antecedent causes may be numerous, too complicated, or too interrelated for analysis. Nevertheless, in order to avoid scepticism, this participating sceptic has generally held that knowledge does not require certainty. Except for alleged cases of things that are evident for one just by being true. It has often been thought, that any thing known must satisfy certain criteria as well for being true. It is often taught that anything is known must satisfy certain standards. In so saying, that by deduction or induction, there will be criteria specifying when it is. As these alleged cases of self-evident truths, the general principle specifying the sort of consideration that will make such standards in the apparent or justly conclude in accepting it warranted to some degree.

Besides, there is another view - the absolute globular view that we do not have any knowledge whatsoever. In whatever manner, it is doubtful that any philosopher seriously entertains of an absolute scepticism. Even the Pyrrhonist sceptics, who held that we should refrain from accenting to any non-evident standards that no such hesitancy about asserting to the evident, the non-evident is any belief that requires evidences because it is warranted.

René Descartes (1596-1650), in his sceptical guise, never doubted the content of his own ideas. Its challenging logic, inasmuch as of whether they corresponded to anything beyond ideas.

All the same, Pyrrhonism and Cartesian form of a virtual globular scepticism, in having been held and defended, that of assuming that knowledge is some form of true, sufficiently warranted belief, it is the warranted condition that provides the truth or belief conditions, in that of providing the grist for the sceptics mill about. The Pyrrhonist will suggest that no non-evident, empirically deferring the sufficiency of giving in but warranted. Whereas, a Cartesian sceptic will agree that no empirical standard about anything other than ones own mind and its contents is sufficiently warranted, because there are always legitimate grounds for doubting it. Whereby, the essential difference between the two views concerns the stringency of the requirements for a belief being sufficiently warranted to take account of as knowledge.

A Cartesian requires certainty. A Pyrrhonist merely requires that the standards in case are more warranted then its negation.

Cartesian scepticism was by an unduly influence with which Descartes agues for scepticism, than his reply holds, in that we do not have any knowledge of any empirical standards, in that of anything beyond the contents of our own minds. The reason is roughly in the position that there is a legitimate doubt about all such standards, only because there is no way to justifiably deny that our senses are being stimulated by some sense, for which it is radically different from the objects which we normally think, in whatever manner they affect our senses. Therefrom, if the Pyrrhonist are the agnostic, the Cartesian sceptic is the atheist.

Because the Pyrrhonist require much less of a belief in order for it to be confirmed as knowledge than do the Cartesian, the argument for Pyrrhonism are much more difficult to construct. A Pyrrhonist must show that there is no better set of reasons for believing to any standards, of which are in case that any knowledge learnt of the mind is understood by some of its forms, that has to require certainty.

The underlying latencies that are given among the many derivative contributions as awaiting their presence to the future that of specifying to the theory of knowledge, is, but, nonetheless, the possibility to identify a set of shared doctrines, however, identity to discern two broad styles of instances to discern, in like the manner, these two styles of pragmatism, clarify the innovation that a Cartesian approval is fundamentally flawed, nonetheless, of responding very differently but not fordone.

Repudiating the requirements of absolute certainty or knowledge, insisting on the connection of knowledge with activity, as, too, of pragmatism of a reformist distributing knowledge upon the legitimacy of traditional questions about the truth-unconditionals of our cognitive practices, and sustain a conception of truth objectives, enough to give those questions that undergo of a gathering in their own purposive latencies, yet we are given to the spoken word for which a dialectic awareness sparks the flame from the ambers of fire.

Pragmatism of a determinant revolution, by contrast, relinquishing the objectivity of youth, acknowledges no legitimate epistemological questions over and above those that are naturally kindred of our current cognitive conviction.

It seems clear that certainty is a property that can be assembled to either a person or a belief. We can say that a person, S is certain, or we can say that its descendable alinement are aligned as of p, is certain. The two uses can be connected by saying that S has the right to be certain just in case the value of p is sufficiently verified.

In defining certainty, it is crucial to note that the term has both an absolute and relative sense. More or less, we take a proposition to be certain when we have no doubt about its truth. We may do this in error or unreasonably, but objectively a proposition is certain when such absence of doubt is justifiable. The sceptical tradition in philosophy denies that objective certainty is often possible, or ever possible, either for any proposition at all, or for any proposition from some suspect family (ethics, theory, memory, empirical judgement etc.) a major sceptical weapon is the possibility of upsetting events that Can cast doubt back onto what were hitherto taken to be certainties. Others include reminders of the divergence of human opinion, and the fallible source of our confidence. Fundamentalist approaches to knowledge look for a basis of certainty, upon which the structure of our system is built. Others reject the metaphor, looking for mutual support and coherence, without foundation.

However, in moral theory, the view that there are inviolable moral standards or absolute variable human desires or policies or prescriptions.

In spite of the notorious difficulty of reading Kantian ethics, a hypothetical imperative embeds a command which is in place only given some antecedent desire or project: If you want to look wise, stay quiet. The injunction to stay quiet only applies to those with the antecedent desire or inclination. If one has no desire to look wise the injunction cannot be so avoided: It is a requirement that binds anybody, regardless of their inclination. It could be represented as, for example, tell the truth (regardless of whether you want to or not). The distinction is not always signalled by presence or absence of the conditional or hypothetical form: If you crave drink, don’t become a bartender may be regarded as an absolute injunction applying to anyone, although only activated in case of those with the stated desire.

In Grundlegung zur Metaphsik der Sitten (1785), Kant discussed five forms of the categorical imperative: (1) the formula of universal law: act only on that maxim through which you can at the same times will that it should become universal law: (2) the formula of the law of nature: act as if the maxim of your action were to become through your will a universal law of nature: (3) the formula of the end-in-itself: act in such a way that you always treat humanity, whether in your own person or in the person of any other, never simply as a means, but always at the same time as an end: (4) the formula of autonomy, or considering the will of every rational being as a will which makes universal law: (5) the formula of the Kingdom of Ends, which provides a model for the systematic union of different rational beings under common laws.

Even so, a proposition that is not a conditional p. Moreover, the affirmative and negative, modern opinion is wary of this distinction, since what appears categorical may vary notation. Apparently, categorical propositions may also turn out to be disguised conditionals: X is intelligent (categorical?) = if X is given a range of tasks she performs them better than many people (conditional?) The problem. Nonetheless, is not merely one of classification, since deep metaphysical questions arise when facts that seem to be categorical and therefore solid, come to seem by contrast conditional, or purely hypothetical or potential.

A limited area of knowledge or endeavour to which pursuits, activities and interests are a central representation held to a concept of physical theory. In this way, a field is defined by the distribution of a physical quantity, such as temperature, mass density, or potential energy y, at different points in space. In the particularly important example of force fields, such as gravitational, electrical, and magnetic fields, the field value at a point is the force which a test particle would experience if it were located at that point. The philosophical problem is whether a force field is to be thought of as purely potential, so the presence of a field merely describes the propensity of masses to move relative to each other, or whether it should be thought of in terms of the physically real modifications of a medium, whose properties result in such powers that is, are force fields purely potential, fully characterized by dispositional statements or conditionals, or are they categorical or actual? The former option seems to require within ungrounded dispositions, or regions of space that differs only in what happens if an object is placed there. The law-like shape of these dispositions, apparent for example in the curved lines of force of the magnetic field, may then seem quite inexplicable. To atomists, such as Newton it would represent a return to Aristotelian entelechies, or quasi-psychological affinities between things, which are responsible for their motions. The latter option requires understanding of how forces of attraction and repulsion can be grounded in the properties of the medium.

The basic idea of a field is arguably present in Leibniz, who was certainly hostile to Newtonian atomism. Although his equal hostility to action at a distance muddies the water. It is usually credited to the Jesuit mathematician and scientist Joseph Boscovich (1711-87) and Immanuel Kant (1724-1804), both of whom influenced the scientist Faraday, with whose work the physical notion became established. In his paper On the Physical Character of the Lines of Magnetic Force (1852). Faraday was to suggest several criteria for assessing the physical reality of lines of force, such as whether they are affected by an intervening material medium, whether the motion depends on the nature of what is placed at the receiving end. As far as electromagnetic fields go, Faraday himself inclined to the view that the mathematical similarity between heat flow, currents, and electro-magnetic lines of force was evidence for the physical reality of the intervening medium.

Once, again, our mentioning recognition for which its case value, whereby its view is especially associated the American psychologist and philosopher William James (1842-1910), that the truth of a statement can be defined in terms of a utility of accepting it. Communicated, so much as a dispiriting position for which its place of valuation may be viewed as an objection. Since there are things that are false, as it may be useful to accept, and conversely there are things that are true and that it may be damaging to accept. Nevertheless, there are deep connections between the idea that a representation system is accorded, and the likely success of the projects in progressive formality, by its possession. The evolution of a system of representation either perceptual or linguistic, seems bounded to connect successes with everything adapting or with utility in the modest sense. The Wittgenstein doctrine stipulates the meaning of use that upon the nature of belief and its relations with human attitude, emotion and the idea that belief in the truth on one hand, the action of the other. One way of binding with cement, wherefore the connection is found in the idea that natural selection becomes much as much in adapting us to the cognitive creatures, because beliefs have effects, they work. Pragmatism can be found in Kants doctrine, and continued to play an influencing role in the theory of meaning and truth.

James, (1842-1910), although with characteristic generosity exaggerated in his debt to Charles S. Peirce (1839-1914), he charted that the method of doubt encouraged people to pretend to doubt what they did not doubt in their hearts, and criticize its individualists insistence, that the ultimate test of certainty is to be found in the individuals personalized consciousness.

From his earliest writings, James understood cognitive processes in teleological terms. Though, he held us in the satisfactory interests. His will to Believe doctrine, the view that we are sometimes justified in believing beyond the evidential relics upon the notion that a beliefs benefits are relevant to its justification. His pragmatic method of analysing philosophical problems, for which requires that we find the meaning of terms by examining their application to objects in experimental situations, similarly reflects the teleological approach in its attention to consequences.

Such an approach, however, sets James theory of meaning apart from verification, dismissive of metaphysics. Unlike the verification alist, who takes cognitive meaning to be a matter only of consequences in sensory experience. James took pragmatic meaning to include emotional and matter responses. Moreover, his ,metaphysical standard of value, not a way of dismissing them as meaningless. It should also be noted that in a greater extent, circumspective moments James did not hold that even his broad set of consequences were exhaustive of a terms meaning. Theism, for example, he took to have antecedently, definitional meaning, in addition to its varying degree of importance and chance upon an important pragmatic meaning.

James theory of truth reflects upon his teleological conception of cognition, by considering a true belief to be one which is compatible with our existing system of beliefs, and leads us to satisfactory interaction with the world.

However, Peirces famous pragmatist principle is a rule of logic employed in clarifying our concepts and ideas. Consider the claim the liquid in a flask is an acid, if, we believe this, we except that it would turn red: We accept an action of ours to have certain experimental results. The pragmatic principle holds that listing the conditional expectations of this kind, in that we associate such immediacy with applications of a conceptual representation that provides a complete and orderly sets clarification of the concept. This is relevant ti the logic of abduction: Clarificationists using the pragmatic principle provides all the information about the content of a hypothesis that is relevantly to decide whether it is worth testing.

To a greater extent, and what is most important, is the famed apprehension of the pragmatic principle, in so that, Pierces’ account of reality: When we take something to be rea that by this single case, we think it is fated to be agreed upon by all who investigate the matter to which it stand, in other words, if I believe that it is really the case that P, then I except that if anyone were to inquire depthfully into the finding its measure into whether p, they would arrive at the belief that p. It is not part of the theory that the experimental consequences of our actions should be specified by a warranted empiricist vocabulary - Peirce insisted that perceptual theories are abounding in latency. Even so, nor is it his view that the collected conditionals do or not clarify a concept as all analytic. In addition, in later writings, he argues that the pragmatic principle could only be made plausible to someone who accepted its metaphysical realism: It requires that would-bees are objective and, of course, real.

If realism itself can be given a fairly quick clarification, it is more difficult to chart the various forms of supposition, for they seem legendary. Other opponents deny that the entitles posited by the relevant discourse that exist or at least exists: The standard example is idealism, which reality is somehow mind-curative or mind-co-ordinated - that real object comprising the external world are not independently of eloping minds, but only exist as in some way correlative to the mental operations. The doctrine assembled of idealism enters on the conceptual note that reality as we understand this as meaningful and reflects the working of mindful purposes. And it construes this as meaning that the inquiring mind itself makes of a formative constellations and not of any mere understanding of the nature of the real bit even the resulting charger we attribute to it.

Wherefore, the term its most straightforwardly used when qualifying another linguistic form of Grammatik: a real x may be contrasted with a fake, a failed x, a near x, and so on. To trat something as real, without qualification, is to suppose it to be part of the actualized world. To reify something is to suppose that we have committed by some indoctrinated treatise, as that of a theory. The central error in thinking of reality and the totality of existence is to think of the unreal as a separate domain of things, perhaps, unfairly to that of the benefits of existence.

Such that non-existence of all things, as the product of logical confusion of treating the term nothing as itself a referring expression instead of a quantifier. (Stating informally as a quantifier is an expression that reports of a quantity of times that a predicate is satisfied in some class of things, i.e., in a domain.) This confusion leads the unsuspecting to think that a sentence such as Nothing is all around us talks of a special kind of thing that is all around us, when in fact it merely denies that the predicate is all around us has appreciations. The feelings that lad some philosophers and theologians, notably Heidegger, to talk of the experience of. Nothing, is not properly the experience of anything, but rather the failure of a hope or expectations that there would be something of some kind at some point. This may arise in quite everyday cases, as when one finds that the article of functions one expected to see as usual, in the corner has disappeared. The difference between existentialist and analytic philosophy, on the point of what, whereas the former is afraid of nothing, and the latter thinks that there is nothing to be afraid of.

A rather different set of concerns arise when actions are specified in terms of doing nothing, saying nothing may be an admission of guilt, and doing nothing in some circumstances may be tantamount to murder. Still, other substitutional problems arise over conceptualizing empty space and time.

Whereas, the standard opposition between those who affirm and those who deny, the real existence of some kind of thing or some kind of fact or state of affairs. Almost any area of discourse may be the focus of this dispute: The external world, the past and future, other minds, mathematical objects, possibilities, universals, moral or aesthetic properties are examples. There be to one influential suggestion, as associated with the British philosopher of logic and language, and the most determinative of philosophers centred round Anthony Dummett (1925), to which is borrowed from the intuitivistic critique of classical mathematics, and suggested that the unrestricted use of the principle of bivalence is the trademark of realism. However, this ha to overcome counter-examples both ways: Although Aquinas wads a moral realist, he held that moral really was not sufficiently structured to make true or false every moral claim. Unlike Kant who believed that he could use the law of bivalence happily in mathematics, precisely because it wad only our own construction. Realism can itself be subdivided: Kant, for example, combines empirical realism (within the phenomenal world the realist says the right things - surrounding objects really exist and independent of us and our mental stares) with transcendental idealism (the phenomenal world as a whole reflects the structures imposed on it by the activity of our minds as they render it intelligible to us). In modern philosophy the orthodox oppositions to realism has been from philosopher such as Goodman, who, impressed by the extent to which we perceive the world through conceptual and linguistic lenses of our own making.

Assigned to the modern treatment of existence in the theory of quantification is sometimes put by saying that existence is not a predicate. The idea is that the existential quantifies themselves as an operator on a predicate, indicating that the property it expresses has instances. Existence is therefore treated as a second-order property, or a property of properties. It is fitting to say, that in this it is like number, for when we say that these things of a kind, we do not describe the thing (ad we would if we said there are red things of the kind), but instead attribute a property to the kind itself. The parallelled numbers are exploited by the German mathematician and philosopher of mathematics Gottlob Frége in the dictum that affirmation of existence is merely denied of the number nought. A problem, nevertheless, proves accountable for its crated by sentences like This exists, where some particular thing is undirected, such that a sentence seems to express a contingent truth (for this insight has not existed), yet no other predicate is involved. This exists is, and unlike Tamed tigers exist, where a property is said to have an instance, for the word this and does not locate a property, but only an individual.

Possible worlds seem able to differ from each other purely in the presence or absence of individuals, and not merely in the distribution of exemplification of properties.

No comments:

Post a Comment