The last 100 years of research into the human brain...sees the brain as an organ that works by physical principles just like the other organs in the body...our emotions and higher callings, such as religion, as well as our grubby low-level physical systems like stereo vision and motor control, are products of a machine.

As women are empowered, violence can come down, for a number of reasons. By all measures, men are the more violent gender.

When time permits, I try to see interesting people in the cities I visit. In Seattle, I met Paul Allen, the co-founder of Microsoft, who is shy in personality but flamboyant in his philanthropy.

If you look in general at people who live in anarchy, they have quite high rates of death from either homicide or warfare or both. Anarchy is one of the main reasons for violence, and it may be the most important.

Democracy is an imperfect way of steering between the violence of anarchy and the violence of tyranny, with the least violence you can get away with.

Probably Hobbes got it right when he said that a leviathan, a third party with a monopoly on the use of legitimate use of force in a territory, might be among the biggest violence reduction techniques ever invented.

We can make fun of hockey fans, but someone who enjoys Homer is indulging the same kind of vicarious bloodlust.