 Ryle’s explicit target in The Concept of Mind is what he calls the “Official Doctrine”, which results, he tells us, at least in part from Descartes’ appreciation that Galilean methods of scientific discovery were fit to provide mechanical explanations for every occupant of space, together with Descartes’ conviction that the mental could not simply be a more complex variety of the mechanical. This “two-world”, Cartesian view has distinctive ontological, epistemological, and semantic commitments that each lead to particular philosophical puzzles.