ABSTRACT
David Hume says that the action of the mind in considering a simple object feels very similar to that of contemplating many strongly related objects. He does seem to attribute to 'theologians' some sort of less than numerical distinction between substance and modification. A way to understand Hume's assimilation is to try to see the strangeness of the contemporary view that the whole is a single thing in addition to its parts. Hume goes on to give a parallel account of the attribution of simplicity to a bundle of qualities. John Locke holds that an individual substance consists of a pure substance plus the accidents that inhere in the pure substance. The ancient theory of substance and accident is supposed to make sense of complex unities in a way that respects both their unity and their complexity. The causes of substituting the idea of simplicity are not strong enough, apparently, to just give up on the evident complexity.
