A philosopher explores the many dimensions of a beguilingly simple question. Why did triceratops have horns? Why did World War I occur? Why does Romeo love Juliet? And, most importantly, why ask why? Through an analysis of these questions and others, philosopher Philippe Huneman describes the different meanings of "why," and how those meanings can, and should (or should not), be conflated. As Huneman outlines, there are three basic meanings of why: the cause of an event, the reason of a belief, and the reason why I do what I do (the purpose). Each of these meanings, in turn, impacts how...