 The traditional epistemological problem of other minds is often associated with scepticism. The sceptic raises a doubt about the possibility of knowledge in connection with the mind of another, a doubt which is thought to follow from a more general doubt raised by Descartes concerning our knowledge of the external world. This latter doubt arises in stages, each of which is designed to draw us into a more wide-reaching scepticism: at stage one it is observed that the senses sometimes deceive; at stage two the possibility of an extended dream is considered; and at stage three the possibility is introduced that there is an Evil Demon deceiving me to think that there is a world beyond how things appear. It is with the third stage that Descartes thought we encounter the possibility of universal doubt about an entire domain, in this case the external world. Descartes has found a way to retreat into his own mind, where he claims to find both knowledge and truth: I can know how things appear to me; external things are now in doubt. Cartesian doubt is radical and it has been raised by philosophers not just in connection with our knowledge of the external world, but also of the past, induction, and other minds. 