Abstract
Gilbert Ryle is most famous for accusing the Cartesian dualist of committing a category mistake. Yet the nature of this accusation, and the idea of a category mistake more generally, remains woefully misunderstood. The aim of this paper is to rectify this misunderstanding. I show that Ryle does not conceive of category mistakes as mistakes of predication, as is so widely believed. Instead I show category mistakes are mistakes of conjunction and quantification. This thesis uniquely unifies and explains the wide variety of Ryle’s remarks, judgments, and arguments.