This book is largely the result of snide remarks from my colleagues at Fordham University. I arrived there very interested in skeptical problems, and people like Vincent Colapietro and Merold Westphal would wonder, out loud, why. One time, after I had presented a paper to the department on Humean skepticism, Chris Gowans bluntly asked me why anyone should find this sort of thing interesting. On another occasion, I was asked why I had my heart set on raising the dead – Hume had already been refuted, so why bother doing it again? Remarks like this were only half serious, but they were frequent enough to set me thinking about why I was so interested in skeptical arguments. It certainly was not because I thought that skepticism might be true. In fact, in this sense I was far less skeptical than most of my colleagues. Rather, I came to realize that my interest in skepticism was methodological. Along with a great many other epistemologists, I was interested in skeptical arguments because I thought that they could teach substantive lessons about the nature of knowledge and evidence. It was part of my methodology, in fact, to assume that skepticism is false, and that skeptical arguments must go wrong somewhere. The trick was to say where, and to learn the philosophical lesson contained therein.