Pre-state societies were far more violent than our own.

In the 1970s, many intellectuals had become political radicals. Marxism was correct, liberalism was for wimps, and Marx had pronounced that 'the ruling ideas of each age have ever been the ideas of its ruling class.'

Violent movements attract thugs and firebrands who enjoy the mayhem. Violent tactics provide a pretext for retaliation by the enemy and alienate third parties who might otherwise support the movement.

Technology, ideology, and social and cultural changes periodically throw out new forms of violence for humanity to contend with.

The connections I draw between human nature and political systems in my new book, for example, were prefigured in the debates during the Enlightenment and during the framing of the American Constitution.

All our behaviours are a result of neurophysiological activity in the brain. There is no reason to believe there is any magic going on.

Language is a window into human nature, but it is also a fistula, an open wound through which we're exposed to an infectious world.