It is impossible to take a materialistic view of the universe (i.e. the view that there is nothing but physical material in the world, atoms bouncing off one another in perfectly predictable patterns) and not come to the conclusion that free will is an illusion because your will must ultimately be caused by events in your physical brain which were caused by previous events in your brain, body, environment and so on. It makes no sense to talk about a will that is disconnected from causal chains of biological events.In other words, we have no idea how consciousness can arise from mere chemical reactions in matter, but Lieberman believes that it does despite the powerful intuition that there's something more to us than just the material aspect of our nature. He even acknowledges that his belief in materialism is a "leap of faith":
Given a materialist view of the universe, it makes no sense to talk about consciousness or experience at all. We have absolutely no idea what it is about the three pounds of mush between our ears that allows it to perform this trick of being conscious. If you damage one spot in the visual cortex, a person will cease to see motion. If you damage another spot, they may lose the ability to see things in the right side of their visual field. But we have no idea why those regions cause us to have conscious experience of motion or the right side of the visual field in the first place. Knowing that an engine can’t run without a particular part is not the same as knowing why it can run because of that part.
I am a neuroscientist and so 99% of the time I behave like a materialist, acknowledging that the mind is real but fully dependent on the brain. But we don’t actually know this. We really don’t. We assume our sense of will is a causal result of the neurochemical processes in our brain, but this is a leap of faith.Reflect for a moment on how much one must deny in order to avoid the conclusion that we are something more than just a lump of protoplasm. We must deny the overwhelming sense that we make free choices and that we are responsible for those choices. We must also deny the powerful intuition that we have a conscious mind that is something other than the brain with which it is integrated. We must deny this in order to maintain belief in a metaphysical position which is not, as Leiberman points out, scientific, which is strongly counterintuitive, and which must be accepted not because there's evidence for it but purely on faith.
Perhaps the brain is something like a complex radio receiver that integrates consciousness signals that float around in some form. Perhaps one part of the visual cortex is important for decoding the bandwidth that contains motion consciousness and another part of the brain is critical to decoding the bandwith that contains our will. So damage to brain regions may alter our ability to express certain kinds of conscious experience rather than being the causal source of consciousness itself.
I don’t actually believe the radio metaphor of the brain, but I think something like it could account for all of our findings. It's unfalsifiable which is a big no-no in science. But so is the materialist view — its also unfalsifiable. We simply don’t know how to reverse engineer consciousness. Saying that the complexity of the brain explains why we are conscious is just an article of faith — it doesn’t explain anything. We don’t know why our brains are associated with conscious experience and nothing else in the universe besides brains seems to be.
If we acknowledge just how much we don’t know about the conscious mind, perhaps we would be a bit more humble. We have so much confidence in our materialist assumptions (which are assumptions, not facts) that something like free will is denied in principle. Maybe it doesn’t exist, but I don’t really know that. Either way, it doesn’t matter because if free will and consciousness are just an illusion, they are the most seamless illusions ever created. Film maker James Cameron wishes he had special effects that good. So we will go on acting like free-willing creatures no matter what. Its what we're built to do.
It's true, of course, that free will and conscious minds are illusions if materialism is correct, but how do we know materialism is correct? We don't. Materialism, as Leiberman admits, is simply a metaphysical preference, and it's embraced, in my opinion, largely because to acknowledge the existence of a mind is to acknowledge a key element in the worldview of Christian theism, a step many modern thinkers are loath to take.
That'd be their business, of course, except that so many of them - unlike Lieberman - insist on telling those who believe these powerful intuitions exist in us precisely because they correspond to reality, that they're irrational.
In order to sustain their materialism the materialist has to deny what everything in their experience is telling them is true, and then they try to persuade us that the worldview which most comfortably accommodates and explains this experience, Christian theism, is a non-rational and superstitious alternative.
It's a very peculiar position to take.