Christof Koch and I see eye to eye on a few things. For one, we're both Mac-heads. (Although I have no Apple logos anywhere on my body). For another, he used to be a neuromorphic engineer: building analog neurons out of silicon. A couple of nights ago I came across a podcast talk by Koch and found we had something else in common... neither of us see any evidence for the existence of free will.
Since I'm a physicist by training (he's a biophysicist and neuroscientist, now focusing on consciousness), much of his argument was familiar to me. First, obviously, classical mechanics is deterministic: cause and effect. No room for free will there... Second, even though some classical systems are mathematically complex (or chaotic)—which means that you cannot predict their behavior far into the future—they are nevertheless still deterministic. You might not be able to figure out what's going to happen next, but it's still going to happen.
Then we get to the ugly subject of quantum mechanics. Although we don't know what's going to happen next—whether the photon will transmit or reflect—we know what the probabilities are. So those probabilites cannot be messed with. The only place where there is wiggle room for something spooky to happen is in how the actual result emerges from the probability distribution of possible results: in the jargon, the collapse of the wavefunction. However, Koch points out, there is absolutely no evidence that anything supernatural is happening here... He also torpedoes the claim that some kind of quantum computing is going on in the brain: the timescales, distances, and temperatures at which neural processes operate are such that quantum processes average out and are not significant.
Next in his talk he makes a little diversion into the subject of downward causation. This is the idea that events don't have to start from particle physics (or string theory, or whatever) and work up. They can go from big subjects like economics or politics down. You lose your job because of economics, not physics, goes the argument. As long as everything operates within the bounds of physics, it's claimed, there's no problem. But how does economics make the particles that were stationary get up (literally en masse) and walk out the door? I've never understood this idea since philosopher and computer scientist Aaron Sloman introduced it to me eight years ago or so. Christof could not make sense of it either.
So back to real science. It turns out that, even if you thought you could get a little spookiness out of quantum mechanics, the brain seems not to be set up for free will either. According to work by Benjamin Libet, we may think that we are making conscious decisions, but it turns out that our unconscious brains make the decision first, then lets our conscious brains know. This can be seen through a surge of brain activity that occurs before we are aware of having made a decision. So any sense that we are consciously weighing up our options before deciding what to do seems to be an illusion. (There's some interesting evidence on this related to hypnosis too).
So, Koch argues, even if there is some remote chance that quantum mechanical outcomes can be modulated by something supernatural, it seems like we make decisions unconsciously—without conventional deliberation—anyway.
It was a great talk, and one that I have probably not done justice to here. I recommend you listen to it yourself if you're at all interested.
Two reservations though. I wish it hadn't been presented in a school of divinity, where I strongly suspect that many in the audience will ignore all the caveats and say the soul resides in quantum behavior. I also wish it hadn't been funded by the Templeton Foundation, a group with the goal of blurring the boundaries between science and religion.