Answering Scepticism presents answers to two types of classical scepticism, put forward by Descartes. One is scepticism about knowledge of the existence of an external world. The other is scepticism about whether we know anything about what is presently going on around us. These scepticisms are widely considered to be among the great perennial problem-syndromes of philosophy, and have been the subject of intense discussion for centuries. A distinctive feature of these forms of scepticism, in contrast to other perennial philosophical problems, is that nearly no one has taken what appears to be one side of a key dispute: nearly no one really believes that we lack the sceptically doubted knowledge. Tyler Burge's closely reasoned and compelling account of these problems begins with this point. Sceptical challenges do not show knowledge to be difficult; and answering scepticism's challenges, even being aware of them, is completely unnecessary for having the knowledge that they purport to threaten. Classical scepticism does not actually threaten knowledge, although it poses as a threat. Burge stresses the fact that answering scepticism requires relying on only a sub-set of good reasons--namely those that do not beg a question at issue. Meeting that requirement yields deeper understanding of knowledge, reason, epistemic support--and deeper understanding of what it is to understand these matters deeply. The two arguments against the two sceptical challenges focus, respectively, on understanding and reason. Of deep interest to potential readers is that the framings and the arguments make important contributions not only to epistemology and meta-epistemology, but also to philosophy of mind, metaphysics, philosophy of perception, philosophy of mathematics and logic, theory of reasoning, philosophy of language, philosophy of action, and history of philosophy.