John Grey on “Conway’s Ontological Objection to Cartesian Dualism”

John Grey, “Conway’s Ontological Objection to Cartesian Dualism” Philosopher’s Imprint 17.13 (July 2017),


Anne Conway disagrees with substance dualism, the thesis that minds and bodies differ in nature or essence. Instead, she holds that “the distinction between spirit and body is only modal and incremental, not essential and substantial” (CP 6.11, 40). Yet several of her arguments against dualism have little force against the Cartesian, since they rely on premises no Cartesian would accept. In this paper, I show that Conway does have at least one powerful objection to substance dualism, drawn from premises that Descartes seems bound to accept. She argues that two substances differ in nature only if they differ in their “original and peculiar” cause (CP 6.4, 30); yet all created substances have the same original and peculiar cause; so, all created substances have the same nature. As I argue, the Cartesian is under a surprising amount of pressure to accept Conway’s argument, since its key premise is motivated by a conception of substance similar to one endorsed by Descartes in his Principles of Philosophy.

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