Back in 1814, Pierre-Simon Laplace was mulling over the implications of Newtonian mechanics, and realized something profound. If there were a vast intelligence — since dubbed Laplace’s Demon — that knew the exact state of the universe at any one moment, and knew all the laws of physics, and had arbitrarily large computational capacity, it could both predict the future and reconstruct the past with perfect accuracy. While this is a straightforward consequence of Newton’s theory, it seems to conflict with our intuitive notion of free will. Even if there is no such demon, presumably there is some particular state of the universe, which implies that the future is fixed by the present. What room, then, for free choice? What’s surprising is that we still don’t have a consensus answer to this question.
Jerry Coyne, also responding to Pigliucci, thinks determinism should change our understanding of morality:
It’s my contention that, in light of the physical determinism of behavior, there’s no substantive difference between someone who kills because they have a brain tumor that makes them aggressive (e.g., Charles Whitman), and someone who kills because a rival is invading their drug business. We need to reconceive our judicial system in light of what science tells us about how the mind works. And that’s why discussing the bearing of neuroscience and philosophy on free will is far more important than our usual academic discourse.