We got Hawking's new book, The Grand Design, delivered yesterday afternoon. I've only had a chance to browse a bit, but I was very surprised to turn to this passage in the second chapter.
Do people have free will?...Though we feel we can choose what we do, our understanding of the molecular basis of biology shows that biological processes are governed by the laws of physics and chemistry and therefore are as determined as the orbits of the planets. Recent experiments in neuroscience support the view that it is our physical brain, following the known laws of science, that determines our actions, and not some agency that exists outside those laws. (pp. 31-32)
Hawking is a determinist. So there's no agency, no free will - no rationality or reason either - because human beings operate under a closed system of laws. Now I really have to ask the obvious and it's not a rhetorical question: Why did Hawking write this book? Did he do it because he hopes to reason and persuade those who disagree and clarify the thinking of those that agree? Does he desire to share the outcome of his investigations and thinking with others? Those would be futile goals as a determinist. Maybe he does think he wrote it because he was determined to. But I suspect Hawking has a true and not illusory desire to offer his arguments and convince people to agree with him.
He concludes that we are "biological machines because neuroscience has demonstrated this through experiments such as "electrically stimulating the appropriate regions of the brain" and creating "in the patient the desire to move the hand, arm or foot...." This experiment doesn't prove that "free will is just an illusion." Because the brain's regions can be mapped and electrically stimulated according to physical laws doesn't mean that there is no agency, that there isn't something immaterial, the mind, that normally interacts with the brain. Because the brain is subject to physical laws when stimulated doesn't exclude the possibility of agency working with the brain and that agency is not subject to physical laws because it isn't physical.
This experiment attempts to show that since the brain can be stimulated artificially, agency is nothing more than the brain operating by physical laws. This is reductionism, attempting to identify agency with the physical operations of the brain. But for this identity to work it means that everything true of the brain states has to also be true of the mental states, and that isn't the case. There are irreducible facts about mental states that aren't true about physical states. Mental states are inner, private, and immediate to the subject having them; brain states are not. Mental states have a first person perspective; brain states don't. Mental states fail to have crucial features that characterize physical states, and visa versa. Brain states have spatial extension and are available for third person access; mental states don't and aren't.
Science hasn't proven that there is no agency. Determinism has consequences that undermine science and rationality. Maybe Hawking and others are willing to bite that bullet and say that his book is actually a meaningless thing, nothing more than a predetermined outcome in a long series. But that just doesn't fit with our experience of ourselves and life, and there's more reason to believe that than to think this it's an illusion of physical laws operating. I think Hawking's work actually is meaningful, not mechanistic. I think he's truly brilliant though mistaken, not just operating according to laws. I think science is a meaningful field of investigation, not a rote exercise of what we've been determined to do.
When materialist presuppositions lead to making such counterintuitive claims, it's time to reexamine the presuppositions. That's what's at work here, not science.