Existence Unperceived

Professor Sir Peter Strawson is properly honoured by the 12 essays written for this anthology. Unlike the papers in some other collections of this kind, most of these are addressed to issues in which Strawson has a serious interest and on which he has done substantial work. It is therefore delightful to find that Philosophical Subjects also contains Strawson’s replies to each of the essays presented to him. Strawson’s prose is elegant, even if his points are sometimes somewhat elusive: one wishes all academics could write as well as he does. He begins each reply with a generous statement of the issues on which he and the person writing about him are in accord, and then discusses points of difference. It might be popularly supposed that philosophers would be especially susceptible to persuasion by rational argument. But philosophers can be as pig-headed as anyone else: indeed, ingenuity can sustain perversity. Strawson, however, displays a wholly admirable grace; he is more than willing to change his mind when he is presented with a good reason for doing so. Thus, since sustained dialectical exchange is the medium of real philosophical work, one can get a sense of what it is like to do philosophy (which is how those in the trade typically put it) by reading Philosophical Subjects.

A number of philosophers think that the most interesting essay in the book is Gareth Evans’s ‘Things Without The Mind – A Commentary upon Chapter Two of Strawson’s Individuals’: Evans, who died last year at the age of 34, was a former pupil of Strawson’s. (It is, incidentally, a pity that there is no contribution from Strawson’s own tutor, the excellent H.P. Grice, an Oxford man now at Berkeley in California.) Evans’s theme goes back to Kant. Kant thought that we need no experience of objects in space to justify believing that space must conform to Euclid’s (or, more accurately, Theaetetus’ solid) geometry: can you even picture a non-Euclidean space? In the terms of art Kant introduced, his view was that Euclidean geometry is known a priori. Kant explained how that should be possible by the idea that the mind must impose spatial structure on experience in order that it be experience of external objects existing independently of our perception of them; in Kant’s terms, space is a pure a priori form of intuition. Kant’s view of geometry has not fared well in this century. A conventional wisdom has it that Einstein’s General Theory of Relativity, our best empirical bet as to the structure of the universe, was a discovery from experience that Euclid’s geometry is not even true of spacetime (which is not space), let alone known a priori. But weakenings of Kant’s view have long been defended. Russell, in his first book, An Essay on the Foundations of Geometry (his prize essay for his fellowship at Trinity College, Cambridge, published eight years before the Special Theory of Relativity), argued that we know a priori of space that it must have its projective properties (roughly, those properties of figures necessarily shared with their shadows), but not its metric properties (a shadow is usually of a different size from the figure casting it).

Strawson weakened Kant’s view even more than Russell. In the second chapter of Individuals, Strawson imagines a being whose experience is entirely auditory. He then argues, as Evans puts it, ‘that the concepts of an objective world, crucially the idea of existence unperceived, would not have any application in the experience of such a being unless that experience provides him with at least some analogue of space. Such an analogue can be provided in a purely auditory experience if each experience of a particular auditory phenomenon is accompanied by the experience of a master-sound – a constant sound whose variations in pitch enable the subject to give substance to the idea that he is moving.’ This being might then suppose that there are sounds, that his experiences are experiences of sounds, and that if he were experiencing the master-sound at a different pitch, the other sounds he would then experience exist ‘there’ unperceived by him. The master-sound’s pitches are analogues of places at which sounds might exist unperceived, and so objectively. Evans first objects to the master-sound. Hero, as Evans and Strawson call the being, need notice only differences in the pitch of the master-sound to distinguish other sounds. Strawson makes no use of the ordering of pitch-levels by higher and lower, so he has no analogue of the dimensionality essential to space. Evans next proposes an alternative to the master-sound. Suppose Hero can first establish short-term generalisations of the form: after any experience of type A but before any experience of type C, there is an experience of type B. With them, he might conjecture a one-dimensional map of the world. If now the sounds he experiences change but their order does not, he can suppose that he but not they have moved; while if two of them change places in the ordering, he can suppose they but not he moved.

He is thus on his way to distinguishing how it is with him from how it is with his world, and so some way towards the idea of an objective world independent of him. But Strawson also wants to connect re-identification and objectivity: the idea of something existing independently and objectively seems to involve the idea that it might exist unperceived between different perceptions of it. That in turn seems to require making sense of distinguishing between a later perception of something qualitatively indistinguishable from the earlier and a later perception of something continuous with the earlier. Evans says: ‘in a spatial world, and possibly only in a spatial world, there can be distinct but simultaneous instances of the same universal.’ This is a synchronic analogue to the diachronic distinction Strawson wants. (Evans’s suggestion that only in a spatial world can there be distinct but simultaneous instances of the same universal is dubious: the attribute of being a number is as universal as any, but the numbers are an infinity of non-spatial, eternal – and so simultaneous – instances of it.) But, Evans argues, Strawson has provided Hero with no apparatus to distinguish between a universal being instantiated (perhaps, unbeknown to Hero, by various things) during a gap in experience and an individual instance of it persisting during a gap: unless, that is, he has smuggled into objectivity the spatiality he intended to argue out of it.

Evans then attempts to construct another argument for Strawson’s view. For Hero to make sense of the idea of unperceived existence, it would suffice for him to have something like a theory about the causation of his experience, and in particular a theory which allows for the possibility that should certain conditions fail, then there will be things he fails to perceive. Such a purpose would perhaps be best served by something like the traditional distinction between primary and secondary properties. According to the tradition, secondary properties are dispositions to produce experiences; colour is supposed to be secondary. All other properties, those independent of experiences, are primary. It should be noted that (a) those properties essential to objects as space-occupying matter (mass, volume, solidity, motion) are primary, and (b) we think of such properties as constituting the nature of an object in virtue of which it can cause experiences in us, so (c) such primary properties put a flesh of actuality on what would otherwise be a ghostly unperceived existence of something having only secondary properties (i.e. unrealised potentialities). But, Evans argues, there is no way to analyse or construct such a system of primary properties of space-occupying objects out of purely and essentially sensory and experiential concepts: it is a major lesson of 20th-century attempts actually to effect such a reduction that it is doomed. Our system of concepts of primary properties is more like a primitive theory of the world. If the sources of the conceptual resources of that system are constrained by an atomistic empiricism, then those concepts are simply not to be had.

Strawson seems not to hesitate to grant all this to Evans, and at this point I began to wonder just what interest there could be left in the project Strawson undertook in the second chapter of individuals. Strawson himself suggests that Hero might take secondary properties to be primary, and in this way construct a proto-theory of a world quite unlike ours. Even if this is possible, it seems to require of Hero mistakes so egregious that it may be hard to tell whether Hero knows what he is thinking. Strawson and Evans conspire to pose one of the great problems of contemporary theory of knowledge with exquisite acuteness: if atomistic empiricism does not suffice to derive the concepts necessary for understanding nature, then to what constraints, if any, is such derivation subject?

Having devoted so much space to the exchange between Evans and Strawson, I should add that there is much more here which is rich and subtle. It is a toss-up which are the worst papers in Philosophical Subjects. For some time, John Searle has been in the business of refuting David Hume’s thesis that purely normative or evaluative claims cannot be derived from purely factual claims. This has generated a certain amount of argument in the journals. Jaakko Hintikka is one of Searle’s critics. In ‘Prima-Facie Obligations’, Searle executes a hatchet job on Hintikka. I do not understand why this bad-tempered essay belongs in a festschrift for Strawson. But then perhaps neither does Strawson – he gives less than a sentence to responding to it. In ‘The Individuation of Proper Names’, L. Jonathan Cohen argues that, for example, one and the same name, ‘Aristotle’, denotes both the ancient philosopher and the modern ship-owner. This leads him to a meta-linguistic theory of naming: whether ‘Cicero denounced Cataline’ is true will depend on how Cicero is named. That in turn leads him to the conclusion that Cassius Clay might not be identical with Muhammad Ali. This is not a subject on which Strawson has ever expressed a burning interest, but he is interested in reference in general. He sketches the view that when in an utterance a proper name designates an individual, then the truth-grounds of the utterance, as far as the name is concerned, turn simply on the denotation that name actually has in that utterance: he then points out that it is obvious on this view that true identity statements with proper names flanking the identity predicate are necessarily true. (Cohen’s charge that the Barcan proof of this begs the question seems to require a special justification for applying Leibniz’s Law – identical things have all their properties in common – to any properties other than those expressed by atomic predicates.) Strawson argues in favour of the view he sketches by distinguishing between the conditions ensuring that a name in an utterance designates a particular thing and the contribution the name makes to the truth-grounds of that utterance. Strawson’s distinction seems to me a contribution to clarity.

The most distinguished contributors to Philosophical Subjects are probably Professor Sir Freddie Ayer and W.V. Quine. Ayer and Strawson enlighteningly discuss the latter’s views on free will in his essay ‘Freedom and Resentment’. Quine and Strawson rekindle their old controversy on the eliminability of proper names. It seems to me that most of the time they misunderstand one another’s purposes. This has, I think, happened to Quine before. When Quine and Carnap engaged once again on analyticity in the Schilpp volume on Carnap of 1963, then it seemed that neither saw what the other was or was not willing to take for granted or call into question. In a way, Quine is a radical sceptic, perhaps even more so than Hume; in a way, Strawson is a philosophical conservative, perhaps even more so than Kant.