Causal Power and Perfection: Descartes's Second a Posteriori Argument for the Existence of God

Abstract: The third Meditation is typically understood to contain two a posteriori arguments for the existence of God. The author focuses on the second argument, where Descartes proves the existence of God partly in virtue of proving that Descartes cannot be the cause of himself. To establish this, Descartes argues that if he were the cause of himself, then he would endow himself with any conceivable perfection. The justification for this claim is that bringing about a substance is more difficult than creating an attribute, so anything that can do the former can do the latter. While current explanations of this justification are either implausible or inadequate, the author argues that this principle derives support from a scholastic distinction between being-as-such and determinate being. With this distinction in view, we can make sense of Descartes's argument without appealing to ambiguous or inadequate notions.