Can Hume's Use of a Simple/Complex Distinction Be Made Consistent?

424 CAN HUME'S USE OF A SIMPLE/COMPLEX DISTINCTION BE MADE CONSISTENT? There is little doubt that Hume equivocates on the distinction between simple and complex impressions and ideas. Sometimes he identifies properties such as colors and shapes as simples. This is what he does, in fact, when he first introduces the distinction: Simple perceptions or impressions and ideas are such as admit of no distinction nor separation. The complex are the contrary to these, and may be distinguished into parts. Tho' a particular colour, taste, and smell are qualities all united together in this apple, 'tis easy to perceive they are not the same, but are at least distinguishable from each other. Later, however, Hume speaks of simples not as qualities (or, of course, as substances) but as objects, i.e., things with properties: it is not red and round that are the simples but the red, round spot. He says, for example: Before I leave this subject I shall employ the same principles to explain that distinction of reason, which is so much talk'd of, and is so little understood, in the schools. Of this kind is the distinction betwixt figure and the body figur'd; motion and the body mov'd. The difficulty of explaining this distinction arises from the principle above explain'd, that all ideas, which are different, are separable. For it follows from thence, that if the figure be different from the body, their ideas must be separable as well as distinguishable; if they be not different, their ideas can neither be separable nor distinguishable (T 2425 ). 425 A genuine inconsistency with regard to the simple/complex distinction would have far reaching implications for Hume's system. Even the question concerning his understanding of necessity may be affected. It has been argued, for example, that what Hume believes separates the philosophical relations that are necessary from those that are not is that the former are internal relations. The suggestion is that the doctrine of internal relations, which is inextricably tied to a specific characterization of a simple/complex distinction, provides the essential contrast Hume needs for his ultimate denial that the causal relation is necessary. The consequences are compounded if we also take Robinson to be right in his attempt to reconcile Hume's 'conflicting' statements about causation in terms of the distinction between the natural and philosophical relations. While it is pointless to deny the ambiguity just set out (and, of course, one must remain constantly watchful to determine how Hume is employing the simple/complex distinction in a particular case), I believe a reconciliation of the two positions is still possible and that there is no genuine contradiction in Hume's system over this issue. The principle shift occurs between the distinction presented in logical terms and its presentation in psychological terms. In the latter instance what Hume seems to be worried about is Platonism: a metaphysics that countenances the existence of unexemplif ied qualities. This is most evident in the passage above where Hume, in effect, makes the following argument: if it were the case that (1) what is distinguishable in thought is separable in reality; and (2) figure and body are 426 distinguishable in thought; then it would follow that (3) figure and body are separable in reality. However, (3), i.e., Platonism, is false. But then so must be (2). Hume never deviates from this conclusion and its implications for his model of thought throughout the Treatise. It is this argument, for example, which became the basis for Hume's accusation against Locke's theory of abstraction and the foundation of his own view. So far Hume has it that neither thought nor experience present us with colors and shapes in isolation. This is his psychological point. Yet that need not be seen as conclusive with regard to what is to count as a logical simple. Building on his notion of a distinction of reason, Hume says: Thus when a globe of white marble is presented, we receive only the impression of a white colour dispos 'd in a certain form, nor are we able to separate and distinguish the colour from the form. But observing afterwards...