Substance

Locke’s idea of a substance (e.g., a rock, a tree, or a swan) comprises (1) the ideas of the qualities that define its species, and (2) the idea of a substratum in which those qualities inhere. The proper interpretation of (2) is controversial. The traditional view is that substratum is an unperceivable component distinct from any and all of a thing’s qualities; the rival view is that substratum = real essence. This chapter examines three arguments for the traditional view: the argument from change traceable at least to Aristotle, the logico-linguistic argument discussed by J. L. Mackie, and a subtler argument, implicit in Leibniz, based on the division of labor between the referential words and descriptive words in subject-predicate sentences. It discuses the textual evidence that Locke held the traditional view. It argues that despite that view’s incompatibility with Locke’s Empiricism, he accepts it, albeit with misgivings, because of the latter argument.