A Dictionary of Philosophy, Third Edition
. The faculty of apprehending the world specifically through the senses, or the general exercise of it, or particular cases of its exercise. Perception raises problems which form an important branch of epistemology.
The analysis of perceiving is complicated by the variety of its objects (cf. SEEING). How is perceiving the redness of Smith’s face related to perceiving that his face is red, that he is angry, that he is subconsciously afraid? And can one perceive an object without perceiving facts about it?
Usually ‘perceive’ is a ‘success’ or ‘achievement’ word (cf. EPISTEMOLOGY on ‘factive’), i.e. we can only perceive what is there or is true. But this may not always hold, if we allow that Macbeth perceived a dagger, and it does not apply to ‘perceive as’ (cf. SEEING). We can misperceive, i.e. make mistakes about what we perceive.
Perception is thus a complex notion, and two main and connected problems concern its relations to sensory experience, and to intellectual notions like belief, judgment, inference.
Sense-perception obviously involves the senses, but exactly how? Very often we perceive things otherwise than as they are, sometimes knowingly and sometimes not. The penny seen from one side looks elliptical, the candle seen out of focus looks double, the whistle seems to change pitch as the train passes. All this has suggested, by the argument from illusion, that what we ‘directly’ or ‘immediately’ perceive or are aware of (often called SENSE DATA, etc.) sometimes or always differs from what is ‘out there’ in the world: we perceive objects by interpreting or inferring from these sense data. More radically, the fact that we sometimes seem to perceive when we are not strictly perceiving at all, as when we dream or hallucinate, suggests SCEPTICISM about how we can know that an external world exists at all. The former position may be reinforced because we know scientifically how the physical and physiological processes involved inevitably affect the information we get through our senses. (But if the presence of such processes means that we never perceive objects, even when the processes are not distorted, what is it that we never do? What would it be to ‘really perceive’ an object?)
If we do attempt to start from a basis limited to ‘pure experience’, it is difficult, as empiricists from Locke and Hume onwards have found, to get beyond it. The sense data, etc. supposed to serve as a bridge between us and the world end up as a drawbridge that keeps us from the world. This attempt has been attacked in two ways. Firstly, the arguments for it are suspect, and seem self-defeating. We can only contrast appearance with reality if we already have independent knowledge of reality, and the fact that we may be deceived on any occasion does not imply that we may, or even could, be deceived on every occasion. Secondly, it seems impossible to isolate and describe any ‘pure experience’ (the GIVEN). Not only does all describing involve language, and so memory, but experience is ineradicably affected by context and knowledge. The retinal image has two dimensions, but we see the world as having three, even with one eye closed. The penny looks round, as much as it looks elliptical (has ‘looks’ two senses here?), and continues to look so while being turned or moved (object constancy. We select part of what we see as foreground, seen against a background (the figure/ground theory emphasized by Gestalt psychologists), and there is the duck/rabbit phenomenon (see SEEING). As artists know, perceptual reduction, abstracting a basic ‘pure experience’ from our perceptions, is difficult or impossible.
Yet the facts remain that perception involves the senses, that perceptions are normally the basis for beliefs, and that illusions do occur. Any theory of perception should answer questions like these: Is there direct or immediate awareness or pure experience, and if so, has it special objects? If it has, how are these related to physical objects or parts of them, including their surfaces? Do words like ‘looks’, ‘seems’, ‘appears’, always imply doubt, or are they ambiguous between a sense that does and a sense that does not? Is perception something unitary, or has it two parts, a sensory part involving this ‘direct’ awareness and some process of interpretation or judgment based on this? If two parts, are they successive or simultaneous? Does a single account hold for different modes of perception such as seeing, hearing, etc.? Do we in fact perceive physical objects at all? Or do we only infer their existence? Or do we treat them as LOGICAL CONSTRUCTIONS (cf. PHENOMENALISM)? If we do perceive physical objects (and shadows, etc.), under what conditions do we do so? Must we know we are doing so? Must we notice or pick out the object? Are there really such things as unconscious and subliminal perception? What features of an object can we perceive? Its colour? Shape? Nature? Behaviour? Causal properties? Beauty? Suitability for this or that? Does the object play a causal role, and if so, what does it cause, our having an experience or our perceiving the object? And does this role enter the analysis of what we mean by saying we perceive the object, so that to say we perceive something is to say, among other things, that it causes us to do something? Or is it merely that our perceptions of it, or our accompanying experiences, are always in fact caused partly by it? And why does it matter by what route the causal chain operates (cf. MEMORY on deviant causal chains)?
Views giving causation a role in one of these ways are among causal theories of perception. Representative (representational) theories say either that what we perceive is not the object but something else (sense data, etc.) representing it, or that we do perceive the object but only by being directly aware (etc.) of such representatives which may or may not he parts of the object. Causal and representative theories often go together. Realist theories say that whatever it is that is perceived exists independently of being perceived. Naïve realism is properly the view, attributed to the ‘plain man’, that we not only perceive ordinary objects but normally perceive them as they are, by a direct relation without sense data, interpretations, etc., and with ‘as they are’ raising no problems. There is a paradox in attributing any philosophical view to the ‘plain’ non-philosophical man, and in practice ‘naïve realism’ often starts by meaning whatever the plain man would say without reflection (i.e. discounting illusions, etc.), and ends, as the argument develops, by meaning simply realism.
Perceptual usually applies to things as they appear to the perceiver. Thus perceptual consciousness is the total conscious experience of the perceiver qua perceiver. Perceptual objects are whatever it is one perceives, be it sense data, physical objects, or whatever, considered as having just those characteristics they are perceived as having. These are perceptual characteristics (what these are may be unclear, as in the penny case above). Perceptible characteristics, however, are those accessible to perception (e.g. colour but not magnetism). The perceptual field is the total of a person’s perceptual objects at a given moment, not necessarily distinguished as separate objects. Perceived object refers usually to the physical or public object (or shadow, etc.) perceived, considered as having the characteristics it really has. Percept is similar to ‘perceptual object’. It sometimes refers to sense data, but sometimes to the contents of perceptual consciousness for those not holding a sense datum theory (Firth). See also SENSES, SENSATION, SENSE DATA, SEEING, FEELING, PHENOMENALISM.
T.Crane (ed.), The Contents of Experience, Cambridge UP, 1992. (Essays, mainly specially written.)
J.Dancy (ed.) Perceptual Knowledge, Oxford UP, 1988. (Reprinted essays, more recent than Swartz.)
R.Firth, ‘Sense-data and the percept theory’, Mind, 1949–50, reprinted with important addendum (p. 270) in Swartz. (Develops and discusses ‘percept theory’ as against sense datum theory, and discusses perceptual reduction).
E.H.Gombrich, Art and Illusion, Phaidon, 1960. (Argues against isolatability of experience in perception, from point of view of art and with plentiful illustrations.)
J.Heil, Perception and Cognition, California UP, 1983. (Perception involves acquiring belief in a certain way, but belief need not involve language and cannot be analysed in terms of internal representations (see also COGNITIVE PSYCHOLOGY).)
*R.J.Hirst, The Problems of Perception, Allen and Unwin/Humanities Press, 1959. (Introduction, advocating one view.)
F.Jackson, Perception, Cambridge UP, 1977. H.Robinson, Perception, Routledge, 1994. (Two defences of sense data theories).
M.Martin, ‘Sight and touch’, in Crane. (Brings out differences between these).
D.Owens, Causes and Coincidences, Cambridge UP, 1992. (See pp. 143–58 for defence of a causal theory.)
C.Peacocke, Sense and Content, Oxford UP, 1983, chapters 1 and 2. (Rehabilitates sensation as having a role in question about perception, distinguishing sensational and representational properties of experiences.)
*P.Smith and O.R.Jones, The Philosophy of Mind: an Introduction, Cambridge UP, 1986. (Chapter 7 attacks view that perception involves inner objects. Chapter 8 defends view that perception is acquisition of beliefs for which see Heil (above) and Armstrong in Dancy.)
P.Snowdon, ‘How to interpret “direct perception”’, in Crane. (Defends version of direct realism, taking sense data and argument from illusion seriously, though without accepting them.)
R.J.Swartz (ed.), Perceiving, Sensing and Knowing, 1965. (Reprinted essays with bibliography.)
J.J.Valberg, ‘The puzzle of experience’, in Crane. (see esp. pp. 18–32 for statement of argument from illusion. Cf. also his book The Puzzle of Experience, Oxford UP, 1992, from which this extract is reprinted.)
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