Paul Bloom

Once we accept violence as an adaptation, it makes sense that its expression is calibrated to the environment. The same individual will behave differently if he comes of age in Detroit, Mich., versus Windsor, Ontario; in New York in the 1980s versus New York now; in a culture of honor versus a culture of dignity.

Empty heads, cognitive science has taught us, learn nothing. The powerful cultural and personal flexibility of our species is owed at least in part to our starting off so well-informed; we are good learners because we know what to pay attention to and what questions are the right ones to ask.