|Free will is incompatible with physical determinism|
I don't think there is a contradiction. People can be predictable - doesn't mean they didn't make their own choice.
For example, let's say you wanted ice cream and had to choose between chocolate and vanilla. You pick vanilla. Then, someone turns back time! Would you still choose vanilla? Yes, because why would you make a different decision than the first time?
Even if your actions are predictable doesn't mean that you didn't have some kind of free will in play. You can't have absolute free will, since our conscious minds depend on an imperfect evolution-built brain, but that's another argument.
It would actually make less sense to say we had free will if our actions were unpredictable and could change. I was watching The Melancholy of Haruhi Suzumiya, where for 8 episodes the universe was stuck in a time loop, but things changed ever so slightly every loop, even though the characters (most of them anyway) weren't aware of the time loop.
If you had to make the same decision in the exact same situation, why would your free will dictate you to make a different one than last time? The explanation would have to lie in some inherit chaos in physics, where certain principles of physics lead to an unpredictable universe (heisenberg's uncertainty principle). This doesn't disprove free will, but its there.
Then you could more easily say free will doesn't exist since our decision making and thought processes are unstable. However, just the idea that our decisions are predictable doesn't mean we didn't make them from our own free will.
Free will is the ability, at least to some extent, to decide for ourselves. If understanding where every atom is in the brain allows you to predict someone's actions, that doesn't necessarily mean that free will as we know it cannot exist, only that it's predictable.
|If there's no other free physical process, what makes thoughts special?|
Other physical processes don't give rise to logical reasoning and thoughts. If we go back to AI, you may be able to map decisions back to some piece of code. But what if an AI achieved consciousness? It wouldn't mean that you can't map its decisions anymore to some kind of code (the code that allows consciousness), but it would mean (if enabled) that the decisions made would be ones IT was happy with or at least wanted to make.
What would make us happy or content in itself arises from evolutionary processes and therefore predictable. That, in turn, perhaps, makes the decisions we come to also predictable. But it still came from our brains after deliberation.
|Having free will means having the capacity to make decisions independently of any physical process|
That's not a requirement that I've read anywhere. This level of "free will" is impossible. It would be like trying to configure your brain without using your brain. Where would your preferences be? Even if you had a knowledge bank somewhere, there's no ability to think.
Free will is not some mystic voodoo that requires a soul. It's simply our ability to internally deliberate on decisions we make.
To put it in other words, a physical being uses physical processes to make decisions. Physical processes created free will and physical processes are predictable. Therefore, free will is predictable.
You may say that your internal deliberations are forced on you, because they could not have happened any other way according to physics. However, "forced" would mean against my will. But instead, our thoughts (usually) come from our will. Our will runs on physics. This may mean it's predictable. And when something is predictable, we tend to think it was forced, though that's not necessarily true.