In this paper I criticize arguments by Pauline Phemister and Matthew Stuart that John Locke's position in his An Essay Concerning Human Understanding allows for natural kinds based on similarities among real essences. On my reading of Locke, not only are similarities among real essences irrelevant to species, but natural kind theories based on them are unintelligible.

In this paper I criticize the interpretations of John Locke on natural kinds offered by Matthew Stuart and Pauline Phemister who argue that Locke’s Essay Concerning Human Understanding allows for natural kinds based on similar real essences. By contrast, I argue for a conventionalist reading of Locke by reinterpreting his account of the status of real essences within the Essay and arguing that Locke denies that the new science of mechanism can justify the claim that similarities in corpuscular structure imply (...) similarities in sensible qualities. I argue further that Locke rejects as meaningless any talk of kinds that appeals to similarities among real essences. On my reading of Locke, similarities in real essences are not only irrelevant to species, but natural kind theories based on themare unintelligible. (shrink)

In this paper, I will argue that Locke is a substance dualist in the general sense, in that he holds that there are, independent of our classificatory schema, two distinct kinds of substances: wholly material ones and wholly immaterial ones. On Locke’s view, the difference between the two lies in whether they are solid or not, thereby differentiating him from Descartes. My way of establishing Locke as a general substance dualist is to be as minimally committal as possible at the (...) outset, especially with respect to the classic debates on Locke’s positions in this domain, including those concerning substrata, real essences, and the like. Nonetheless, I show that minimal commitments about Locke’s primary/secondary quality distinction are sufficient to derive some substantive conclusions about his positions on these issues, as well as that he is a general substance dualist. (shrink)

In this encyclopedia entry I canvass the current interpretations of John Locke's concept of Real Essence and the role it plays in his philosophy.