We've all asked, "What is the world coming to?" But we seldom ask, "How bad was the world in the past?" In this startling new book, cognitive scientist Steven Pinker shows that the past was much worse. Evidence of a bloody history has always been around us: genocides in the Old Testament, gory mutilations in Shakespeare and Grimm, monarchs who beheaded their relatives, and American founders who dueled with their rivals. The murder rate in medieval...