But he's right, we don't have free will, at least as far as physics is concerned. Given a powerful enough computer, the motion, charge, spin, etc. of every atom could be determined, including those that make up the neurons in your brain. Thus, the decision-making process happening in your mind is itself deterministic. However, there are far too many variables for this to ever be computed, so the way our brains have evolved, we perceive the world with free will.

I like the way Christopher Hitchens put it:

'You have no choice but to have free will'