This article examines the post-Ryle developments in philosophy of mind and psychology, in particular tracing the emergence of the concept of a mental state. The climate immediately following the large-scale rejection of Descartes seems rather hostile to the idea of mental properties as internal states that cause behaviour. In this context, the emergence of the reificatory view of mental states is quite surprising, and it appears to stem from Putnam's adoption of the Turing machine (including the Turing state) as a model for human psychology. I conclude that the success of the “mental state” is down to the fact that it neatly conforms to the picture painted by the metaphorical expressions we use when talking about minds and mental things, and that its success is more accidental than inevitable.