it seems basic to me that events can be caused, chosen, or random.

Can you give a specific, meaningful definition of "choice" that cannot be reduced to causality, randomness, or some mixture thereof? I've tried, and I really can't think of any that hold up under scrutiny. Most of my attempts (from back when this seemed like a serious problem to me) turned out to be meaningless or circular definitions, or homunculi. Even if, for example, you posit an extraphysical soul that controls one's body like a puppet, then the question of "How does the soul make its choices?" is still meaningful — a given choice can either be for a reason or for no reason — and there would in theory be a right answer, even if there we somehow could never find out what it was (and we probably could anyway, by studying behavior and reverse-engineering general principles: the same thing science always does, even if it cannot directly study the underlying mechanism).

You might have to answer ata's question before I can say more. But try this. Take a stock example of a free choice. Smith finds a wallet on the ground. He decides to return it. Why did he return it? Now maybe Smith didn't choose to return it, maybe someone made him do it by hypnotizing him. This is obviously a causal event, presumably we can agree that Smith isn't using libertarian free will here. But maybe he did choose to return it. Even then though we don't just stop wonder "why?". When we ask for an explanation of behavior "I chose to" isn't enough. Usually we ask for reasons. Reasons are significant explanations for actions because they appear to be morally significant. We don't usually hold drugged or (were it to happen) mind-controlled people responsible for their actions to the same degree people he choose to act based on reasons. But reasons are still causal explanations. Were returning the wallet not the moral thing to do (say the wallet had proof the owner had committed a heinous crime) then the Smith would have no returned the wallet. Explanations based on reasons can be reduced to sentences about neurons and biochemistry the same way any causal explanation can. The only explanation that I can think of that wouldn't be a causal explanation is if the choice to return the wallet just happened. There was no reason, no cause. It just happened. It could have not happened but in did. Thats what we mean by undetermined or random. There is a middle ground, some things can be more likely than other things. Some philosophers have tried to argue that brains are sensitive enough to quantum level indeterminacy that our actions cannot be perfectly predicted even in principle. But even if this is why Smith returned the wallet it obviously doesn't give Smith the kind of free will libertarians want.

I just don't know what this other thing could be. Determined and indeterminate appear to exhaust the possibility space. Philosophers have tried for a very long time to offer something else up but they inevitably fail.

Can you say a bit more about that? I dislike disturbing other's basic concepts of world-understanding without good reason, but my basic categories are simply threefold: it seems basic to me that events can be caused, chosen, or random.

(An aside: this sort of view is common in the free will dialectic - it is an incompatibilist theory, probably of the non-causal type. Jack's objection is a standard one, and for good reason, I believe.)

Perhaps I should state it in a slightly different way. There is no reason for me or anyone else to doubt the clear perception we have of our own free will. Prove to me scientifically that it does not exist, that it is some kind of illusion that all human beings experience.

Fair enough. I'm glad you agree it's an empirical question.

Having got that concession from you, I'll tell you I actually don't agree with Chu-Carroll's analysis. Of course everything is definition-dependent here, but in essence, I don't think free will is an illusion. Rather, I think the opposition of determinism to free will is just mistaken. Determinism does not imply no free will. This position is called compatibilism.

What Chu-Carroll is saying is that free will is not some weird force outside physics that thaumaturgically makes an electron zig instead of zag, causing the miracle of choice. I agree up to there. So if that's what you call free will, then it is an illusion. He then implies "there is no free will." Indeed, not under that definition.

But that's not what I call free will.

See Daniel Dennett's "Elbow Room;" also search this site for "Free Will." Eliezer has done some excellent writing on the subject.