With that definition, a robot can have free will if it is programmed to make predetermined decisions from a set of input variables, independantly of other conclutions that differently programmed robots come to.

No.

In the first scenario, it is perfectly possible that he's already decided to rob a bank. There's no reason why rewinding time should automatically change your mind so that your actions are random.

The second scenario wouldn't really happen, but if it did, it would be because quantum theory made some significant change which caused him to freely change his mind.

There is no disproof of anything in there.

Schopenhauer wrote the best thing I ever read about determinism ( a theory to which I feel inclined). Now, before you tell me that the quantum theory wasn't postulated when he wrote this and blah blah blah, just let me tell you that I don't care about it. I believe that the theory that defends the existence of infinital quantity of universes, and more so, the "logical" problems extracted out of that theory are plain stupid... A product of a ridiculous deduction that's been supported year after year based on a quantum empirical fact (that may or may have not yet been fully understood).
Anyway, what I intended to defend was the idea that we may do "what we will" but we cannot decide the nature of that "will" cause if fact, that's what we are. Time and space (and cause effect) are the "ground" in which the Will manifest itself (by Will, in a ontologic sense, we should understand the real being, regardless of how it appears in time and space).

Pff... this is hard to explain in little sentences, in a second language and hey, when you talk about this kind of things people tend to get defensive because the implications of such affirmations collide with the cosmovision each of us have of the world (and therefore affects us because we are defined to ourselves by the place we understand we occupy in the world we represent to ourselves). This is just as sensitive as religion because it affects the very same things.

My opinion: what we do is already written by a beingless writer in a paper called law of cause effect. There's no way in the world a subjective being or a group of them can mathematically predict in all extent what will happen because the variables are infinite and our methodoly and tools imperfect. Therefore, our sense of freedom is guaranteed. As rational beings, we have a saying in what we do, but that rationality does not scape the very same laws of the physical world (cause effect or even a quantum law if you please).

Bolded: That's a pretty funny equation. (no offense ;)

Underlined: Think about this: When the big bang occured, there was not a single life-form. No decisions could be made, thus either randomness or determined patterns made materials move and finally shape planets and eventually life. If the free will is what shapes randomness (which I really, really don't believe) then you just proved that there is a god. I'd say that it's the other way around though, and that randomness/determined events is what shapes the free will.

This is by far the best comment in this thread so far, and I completely agree.

(I don't believe in quantum effects myself, but I had to include it as it hasn't been disproven)

So if he makes a different decission it's randomness? That doesn't make sense to me, he made a different decission.

If you reverse time to just before the robbery, he'll probably (but not surely) do it again, as the circumstances will be 99.99% similar before the robbery. If you reverse time to several days before, the robbery probably won't happen. This also ties with chaos theory, a small change has huge effects on the long term.

That doesn't mean it's randomness though. There is a complex system behind it, humans are making decissions all the time and those decissions affect the system, which affect other decissions. Of course those decissions are going to be influenced by society, one's upbringing, etc., but all those factors are also made by human decissions.

free will must exist on some level because it depends on someone else for example the man he robbed had many choices he could stop the robber or shake his hand and that ultimately changes fate, or even you trip on the curb and think "what am I doing" then decided not to rob the house. we are bound by threads and every action we take changes the world in some way.

If you have a free will, then you can shape the future. If you don't have a free will then the future and all your future decisions are predetermined or determined by randomness, giving you no control of your actions.

In every moment in time we all have a choice but in that moment we can only make one choice thats the point, think about this if we have free speach we can say anything we want, but we cant because we are bound by rules and law so is that complete freedom of speach?