Hume, Strict Identity, and Time's Vacuum

Hume, Strict Identity, and Time's Vacuum Michael J. Costa It is well known that Hume distinguishes between strict identity and the identity that applies to changeable objects, such as physical objects or persons. Identity judgments that we make with respect to changeable objects are based upon a number offeatures that determine how likely it is for the mind to confuse the perception of such objects with the continuous perception ofan unchanging object. Strict identity can apply only to the latter (T 203-18, 253-63). Even the idea of strict identity, however, is considered by Hume to be a fiction and based at bottom on a confusion. I will concentrate here on Hume's account of the idea of strict identity, and I will try to explain the precise sense in which Hume considers this idea to be a fiction and based upon a confusion. Some very able commentators have dealt with this topic before, but none of the accounts with which I am familiar give adequate attention to the full context of Hume's account in the Treatise. They do not note the degree to which his account develops out ofand depends upon verybasic features of his system, such as his characterization of relations as complex ideas (T 13) and his theory of abstract ideas (T 17-25). Nor do the accounts note the degree to which the idea of strict identity is tied to the idea of time without change (T 64-5), and through that, to the idea of a vacuum (T 53-65).2 I shall argue that viewing Hume's account of the idea of strict identity in light of his accounts of complex and abstract ideas, his account ofthe idea ofa vacuum, and his account oftime without change makes considerable sense of it, at least as an account that it is reasonable for him to hold. I will proceed by examining each of these features in turn. Along the way I hope to make some novel and enlightening interpretative points with regard to complex ideas, abstract ideas, the idea of time, and the idea of a vacuum. I Hume tells us that simple perceptions (whether impressions or ideas) are those which admit of no distinction nor separation, whereas complex perceptions are contrary to these and may be distinguished into parts (T 2). The example that he immediately gives, however, at best clouds the distinction he has made. He says, Tho' a particular Volume XVI Number 1 MICHAEL J. COSTA colour, taste, and smell are qualities all united together in this apple, 'tis easy toperceive they are not the same, but are at least distinguishable from each other (T 2). This may make it seem that simple ideas are universals and that a mere distinction ofreason (see T 24) is enough to show that a perception is not simple; but I think that Hume did not have universals in mind at all with respect to the simple/complex distinction. Every perception-proper for Hume is a particular, an existent (T 66-7). There is, indeed, something more to a universal or abstractideafor Hume than a particular idea, but this something more is a disposition and not another idea or perception. I see no evidence that Hume intended the simple/complex distinction to apply to the dispositions connected with abstract ideas. Note that in the apple example, the ideas mentioned are of different sense modalities. They can be distinguished psychologically, and not merely as distinctions of reason. One can form a distinct idea of the colour of the apple without forming any idea of taste or smell. The shape of the apple would not be distinct in the same way. Any idea of the shape of the apple would, for Hume, also be an idea of some colour or other. This becomes important when we note that Hume characterizes space and time (indeed, all relations) as complex ideas (T 13). He does not mean that these ideas are logically analyzable; he means that any instance of these ideas is psychologically analyzable. Any instance is analyzable into idea parts that can be considered separately in mind from the other idea parts. An instance ofspace or extension...