Do human beings have free will? Are they genuinely responsible for their actions? These questions have persisted all through the history of philosophy, but in the 21st century they have become defined more sharply and clearly than ever. Indeed, a vivid and mighty tension underlies today's intellectual struggles over free will. On the one hand, the rapid advances of several empirical disciplines, notably neuropsychology and genetics, threaten our instinctive affirmation that free will and m...