Steven Pinker: I don’t believe there’s such a thing as free will in the sense of a ghost and a machine, a spirit or a soul that somehow reads the TV screen of the senses and pushes buttons and pulls the levers of behavior. There’s no sense that we can make of that. I think we are . . . Our behavior is the product of physical processes in the brain. On the other hand, when you have a brain that consists of one hundred billion neurons connected by one hundred trillion synopses, there is a vast amount of complexity. That means that human choices will not be predictable in any simple way from the stimuli that I’ve hinged on beforehand. We also know that that brain is set up so that there are at least two kinds of behavior. There’s what happens when I shine a light in your eye and your iris contracts, or I hit your knee with a hammer and your leg jerks upward. We also know that there’s a part of the brain that does things like choose what to have for dinner; whether to order chocolate or vanilla ice cream; how to move the next chess people; whether to pick up the paper or put it down. That is very different from your iris closing when I shine a light in your eye. It’s that second kind of behavior – one that engages vast amounts of the brain, particularly the frontal lobes, that incorporates an enormous amount of information in the causation of the behavior that has some mental model of the world that can predict the consequences of possible behavior and select them on the basis of those consequences. All of those things carve out the realm of behavior that we call free will, which is useful to distinguish from brute involuntary reflexes, but which doesn’t necessarily have to involve some mysterious soul.