There is no topic more fascinating or important than morality. From hot-button political issues to the he-said-she-said of office gossip, morality is on everyone's mind. Cultural conservatives warn of imminent moral decay, while liberals and secularists fear an emerging "Endarkenment," brought on by the right's moral zealotry. Every major political decision — Should we go to war? Should we act to preserve the environment? — is also a moral decision, and the choices we make will determine whether our species will continue to thrive, or be yet another ephemeral dot in evolution's Petri dish.

We and our brains evolved in small, culturally homogeneous communities, each with its own moral perspective. The modern world, of course, is full of competing moral perspectives, often violently so. Our biggest social problems — war, terrorism, the destruction of the environment, etc. — arise from our unwitting tendency to apply paleolithic moral thinking (also known as "common sense") to the complex problems of modern life. Our brains trick us into thinking that we have the Moral Truth on our side when in fact we don't, and blind us to important truths that our brains were not designed to appreciate. Our brains prevent us from seeing the world from alternative moral perspectives, and make us reluctant to even try. When making important policy decisions, we rely on gut feelings that are smart, but not smart enough.

That's the bad news. The good news is that parts of the human brain are highly flexible, and that by depending more on these cognitive systems, we can adapt our moral thinking to the modern world. But to do this we must put aside common sense and think in ways that strike most people as very unnatural.