When I say that my belief that p is fallible or fallibly justified, do I mean to say only that it is uncertain, or do I mean to say more than this? This book considers some of the myriad things that are, or may be, at stake here. In particular, what is the relationship between fallibility and scepticism? Does the former entail the latter? And if not, what explains the appearance to the contrary? The author offers an account of fallibility that answers these questions in a simple and intuitive way.