1. The Better Angels of Our Nature by Steven Pinker (Penguin, $20). A monumental achievement. Pinker, a Harvard psychology professor, draws on 5,000 years of historical evidence to explain in fascinating detail how violence has declined across human history. More broadly, he shows that human beings have learned to treat each other better in general.
2. Thinking, Fast and Slow by Daniel Kahneman (Farrar, Straus and Giroux, $16). Most "idea books" are bloated essays; this one, from a Nobel Prize–winning economist, is worth reading all the way through. Kahneman offers a fascinating set of ideas about how human beings think and reason, for better and worse.
3. The Righteous Mind by Jonathan Haidt (Vintage, $16). A brilliant mixture of political philosophy and sociology. According to Haidt, two reasonable people can find themselves on opposite ends of the political spectrum based on the relative importance each assigns to just six values. The book explains why we embrace certain ideologies better than any other I've read. . . .