Roderick Firth, Sense Data and the Percept Theory, 1949-50.

PART II
THE EPISTEMOLOGICAL IMPLICATIONS OF THE PERCEPT THEORY

The most revolutionary inferences which philosophers have drawn from the Percept Theory are probably those which concern the epistemological status of physical objects; we have already seen, for example, that in recent years some philosophers have used the Percept Theory as a basis for attributing to physical objects the same epistemological status that has traditionally been attributed to sense-data. But there is another possible implication of the Percept Theory which deserves prior consideration because our decision concerning its validity will necessarily influence our analysis of almost all other epistemological issues.

1. THE GIVEN AND ITS INTERPRETATION

We might wonder, specifically, whether acceptance of the Percept Theory can force us to deny completely a fact the recognition of which Lewis has called "one of the oldest and most universal of philosophic insights", the fact, 'namely, that "there are, in our cognitive experience, two elements; the immediate data, such as those of sense, which are presented or given to the mind, and a form, construction, or interpretation, which represents the activity of thought".57 The distinction to which Lewis refers is, in one form or another, so fundamental to most philosophical and psychological systems, that to reject it entirely would necessitate, at the very least, a complete reformulation of these systems. And despite the phenomenological evidence for the Percept Theory, there are undoubtedly many philosophers and psychologists who would find that theory quite incredible if it could be shown to imply that the distinction between what is given, and the interpretation or construction put upon it, is entirely invalid.

But there are, I believe, three rather different senses in which this familiar distinction can be recognised even by those who accept the Percept Theory; and there is only one traditional sense in which the distinction must be denied.

(a) The Given as the Ostensible Physical Object

In the first place it must not be forgotten that the Percept Theory is a theory about perceptual consciousness and that the evidence for it is entirely phenomenological and gathered by direct inspection of many single states of perception. If, therefore, the terms "construction" and "interpretation" are defined dispositionally -- by reference either to a tendency towards bodily behaviour of a certain kind or to a tendency to have certain kinds of conscious experience under certain conditions, or both -- then the validity of the distinction between "the given" and its "interpretation" is entirely independent of, and hence compatible with, the truth of the Percept Theory. Thus for those who accept the Percept Theory the things that are given in perception would be ostensible physical obiects, these being the only sensuous constituents of ordinary perceptual consciousness; and the manner in which these are interpreted would be determined by discovering the dispositions which accompany them. In many contexts, moreover (e.g., in most discussions of learning) the philosophers and psychologists who have distinguished between the given and its interpretation have intended to say nothing that is incompatible with such a theory of the given; to recognise a distinction of this kind, therefore, is to admit the validity, in one historic and important sense, of what Lewis has called "one of the oldest and most universal of philosophic insights".

But that is not all that can be admitted, for it should be remembered that the Percept Theory as I have described it, is a theory limited not only to perceptual consciousness but to the sensuous aspects of perceptual consciousness. It is a theory, to be more precise, about the phenomenological status of the ostensible physical object and the sensuous qualities which clothe it, and it is incompatible with the Sense-datum Theory, as we have seen, precisely because it denies the phenomenological duality of any of these sensuous qualities. If, therefore, a philosopher or 'psychologist happens to believe that the ostensible physical object usually does not exhaust the content of the consciousness during perception; if, for example, he believes that the ostensible physical object is presented together with certain bodily feelings, or with an "ostensible self" or with an "ostensible perceiving self", or with phenomenologically irreducible "beliefs" or "judgements" or "expectations", or indeed with any other possible constituents of consciousness whatsoever, and if, at the same time, he does not believe that any of these constituents are sense-data as traditionally conceived, and is therefore able consistently to admit that sensuous qualities are presented as the qualities of the ostensible physical object and not of any other entity; such a philosopher or psychologist so far as I can see, does not believe anything that is incompatible with the Percept Theory. It might consequently be possible, by defining "interpretation" and "construction" in terms of some of these other constituents of perceptual consciousness, to give a purely phenomenological meaning to these words so that the given (the ostensible physical objectl could be distinguished from its interpretation by direct inspection of perceptual consciousness. Thus the historical distinction could be recognised in another sense, and a sense which would probably represent the principal point that Lewis himself has in mind when he says: "That present datum of experience which is interpreted as 'activity of thought' is just as objective and intrinsically observable a kind of datum as is the phenomenal apearance of an external object".58 Whether or not direct inspection of single states of perceptual consciousness can validate such a distinction is a difficult question, and one which is not strictly relevant to the basic issue under discussion, but there is nothing in the Percept Theory to imply that it cannot.

Some of the examples which Lewis gives to illustrate the distinction between the given and its interpretation, however, require that this distinction be recognised in another sense, quite different from the two so far discussed; and in this other sense the distinction is not compatible with the Percep Theory. Lewis points out the fact that our perceptual experience varies not only with changes in the physical conditions of observation but also with changes in interest, and he illustrates this by showing that the perceived qualities of a fountain pen differ for a child, a writer, and a savage. This fact, of course, is quite compatible with the Percept Theory, for the characteristics of ostensible physical objects do indeed vary with the attitude of the perceiver. But Lewis uses this fact to illustrate the difference between the given and its interpretation, and the distinction in this instance is drawn in a manner which is incompatible with the Percept Theory.

The distinction is drawn between a "presentation", which is supposed to be the constant and given element in the various perceptual experiences of the pen, and its "meaning" or interpretation. Speaking, for example, of the fountain pen in his hand, Lewis says: "It might happen that I remember my first experience of such a thing. If so I should find that this sort of presentation did not then mean 'fountain pen' to me."59 But since by the expression "this sort of presentation" Lewis means a complex of qualia or sense-data60 which are to be distinguished from the qualities of the ostensible pen, it is clear that this expression, for those who accept the Percept Theory, simply has no designatum at all within these states of perceptual consciousness. According to the Percept Theory there simply is no common core of sense-data to "mean" one thing at one time and another thing at another time. It is possible, to be sure, that the ostensible physical object presented in childhood might have had certain properties (e.g., a particular shape ans color) in common with the ostensible physical object presented at the time of writing; in fact this is probably what it would ordinarily mean to say that the two presentations were "of the same sort"; but the particular distinction which Lewis has in mind, and which is essential to the Sense-datum Theory, is not one that can be defined by reference solely to the properties of the ostensible physical objects.

The problem, therefore, for those who accept the Percept Theory, is whether in rejecting this distinction between the given and its interpretation they must also reject as meaningless all the epistemological and psychological principles whose formulation presupposes that the distinction is valid. In view of the historical importance of the Sense-datum Theory it is clear that this problem cannot be lightly dismissed. Whatever one may think, for example, of the ultimate value of the introspective psychology of Wundt and Titchner, it will stretch the credulity of those who are familiar with their experimental work to suggest that the principles which they formulated concerning the relationship between sensation and "meanings" are completely meaningless.61 The conception of the sensory core, moreover, appears to have a certain methodological value, for differences and similarities among sensory cores have been supposed to provide psychologists with phenomenal criteria for deciding just what characteristics of perceptual consciousness can and cannot be explained by reference to physical processes in the sense-organs; it has been supposed, for example, that the fact that two perceptions have similar sensory cores guarantees that all differences between these perceptions must be explained by reference to attitudes (broadly interpreted) and the physiology conditions of attitudes. And it might not be easy, even for those psychologists who accept the Percept Theory, to dispense entirely with such methodological principles.

(b) The Given as the Product of Perceptual Reduction

It seems to me, however, that the solution to this problem is not so difficult as it may appear, for I believe that we can find for these particular psychological purposes, a completely satisfactory substitute for the sensory core as traditionally conceived. We can do this by applying the pragmatic maxim and asking ourselves just how psychologists have actually decided whether or not two perceptions are to be called "interpretations of the same sensory core". And if our methodological analysis in the previous section is correct, this has been decided, of course, by subjecting the two perceptions to the operation of perceptual reduction and comparing the resulting states of direct awareness. If, to use Lewis's example, two different perceptual experiences of a fountain pen are perceptually reducible to direct awareness of similar sense-data -- perhaps long tapering patches of black -- then it would be concluded, no matter how different the ostensible physical objects, that the two perceptions are different interpretations of the same given". For those who accept the Percept Theory, therefore, this "method of verification" can be used define the term "sensory core" in a way which will provide a substitute for the traditional concept. We can say that the statement "These two perceptions are different interpretations of the same sensory core", should be understood to mean: "If these two perceptions were perceptually reduced exactly similar states of direct awareness would be produced in the two cases". And to understand this second statement, of course, we do not need any concepts which are incompatible with the Percept Theory.

Ayer has called such pragmatic definitions as this "definitions in use". "We define a symbol in use", he says, "not by saying that it is synonymous with some other symbol, but by showing how the sentences in which it significantly occurs can be translated into equivalent sentences which contain neither the definiendum itself, nor any of its synonyms".62 By means of this definition in use, then, philosophers and psychologists who accept the Percept Theory can translate into an empirical language statements about the given which would otherwise be verifiable only if the Exposure Hypothesis were valid. In preferring this definition, moreover, they do not necessarily belittle the importance for psychology of either the operation of perceptual reduction or the concept of the sensory core which is defined in terms of it. To deny the existence of the sensory core as traditionally conceived, therefore, is not necessarily to discredit the empirical science erected by psychologists who have assumed its existence, nor even to disparage their method.

Thanks to the definition in use, therefore, there is a third sense in which those who accept the Percept Theory may recognise what Lewis has called "one of the oldest and most universal of philosophic insights". And once a philosopher or psychologist has carefully defined "the given" in this third sense, he might, in some contexts, find it convenient to speak of the sensoy core as if it were literally a constituent of perceptual consciousness. This policy was recommended, as a matter of fact, by Josiah Royce, who, like James, specifically rejected the Sense-datum Theory. Royce recognised the error of confusing direct inspection with any other procedure, such perceptual reduction, in which we merely substitute a new state of consciousness for the one we are supposed to be describing; states of consciousness, he says, contain only those elements which on direct inspection they appear to contain. When we say that a mental state consists of elements which we ourselves do not distinguish in it, he says, we may be confusing the mental state with a physical object, with the brain, with the meaning of the state in a logical process, "or else, finally, we are referring to a more sophisticated state of mind which the psychologist, by his devices for analysis, has substituted for the original and naive consciousness".63 Nevertheless, he suggests, it may be convenient to speak of this "sophisticated state" as if it were part of tthe original and naive consciousness. Such a linguistic device, of course, is quite compatible with the Percept Theory, and may sometimes be very useful.

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Notes

57 Mind and the World-Order, p. 38.

58 Ibid., p. 424.

59 Ibid., p. 49.

60 Ibid., p. 60.

61 See Titchner, A Beginner's Psychology, ch. 1.

62 A. J. Ayer, Language, Truth and Logic, p. 68, Gollancz, 1936.

63 J. Royce, Outlines of Psychology, pp. 109-110, Macmillan, New York, 1903.
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