Ten years ago, the psychologist Steven Pinker published The Better Angels of Our Nature, in which he argued that violence in almost all its forms — including war — was declining. The book was ecstatically received in many quarters, but then came the backlash, which shows no signs of abating. In September, 17 historians published a riposte to Pinker, suitably entitled The Darker Angels of Our Nature, in which they attacked his “fake history” to “debunk the myth of non-violent modernity.” Some may see this as a storm in an intellectual teacup, but the central question — can we learn