Since Descartes it has been common, but arguably misdirected, to think of knowledge of my own mind as particularly certain, and even as the basis of my knowledge of other things. Once this orientation is adopted, other things become relatively problematic. But even if knowledge of other things is somehow protected, the belief that some amongst them have minds like my own is an extra, theoretical, belief whose foundations can quickly seem insecure. The traditional way of arguing for other minds is by analogy . Critics complain that this involves generalizing from the one case (my own) and rather extravagantly supposing that all things resembling me physically also resemble me mentally. It also presupposes that I can make sense of the very notion of another person's consciousness, whereas within the Cartesian world view there is no explanation of how I could acquire such an idea. More social and public approaches to knowledge see knowledge of my own mind as itself dependent upon knowledge of the world, and indeed upon knowledge of other peoples' minds, as these are exhibited in their language and behaviour. See also private language.
Philosophy dictionary. Academic. 2011.