Have you ever asked yourself, or indeed felt the need to ask: How do I know this thought is mine? Many philosophical questions typically begin: "How do I know...?" Some "how do I know" questions may have inadvertently become stereotypical, at least in the eyes of others: the sort of thing that I am told we philosophers are always preoccupied with. How do I know that the world around me is as it appears, or is in fact there at all? How do I know that others have minds, or that they are not some automaton or philosophical zombie (of the kind encountered in Chapter 2)? Each of these questions has indeed been at the forefront of much philosophical inquiry over the years, and continues to occupy that position even today. Any "how do I know" question is, of course, epistemological in nature. An important philosophical method espoused by philosophers interested in epistemology is therefore scepticism.