However, let us examine the two sides of the story first. In the first place, the idea of free will existing. It almost seems it must. You can choose whether or not to move your left index finger now, or the next second, or not all. Plus, as I mentioned earlier, how can people be held accountable for their actions without the idea of their having made their own decisions that allowed them to commit an act that was against a set of laws? If one factors out the idea of free will, many questions open up, whose iterations never seem to end, as is what happens when someone tries to answer a subjective question objectively. So the answer to this subjective question must be subjective as well, hence free will must exist to some extent. Not to mention that the causal model of the universe entirely ignores superstring theory of branching time, and quantum probability. To try to eliminate this idea opens up a whole untangle-able can of worms.

So, who is right?
Well, it's presented as a dichotomy, so let's step back and allow for the idea that neither are 100% correct. First, let's do this by realizing that there is a difference between free will and just plain will. Second, that even in the causal model of the universe, you still have to deal with your epistemic horizon, that is, you can only know so much about yourself and what makes you do what. Third, quantum probability does factor in to allow for superstring theory, but only over a broad spread.
Here is the solution as I see it: free will itself is an illusion, but will, the intent, is entirely different and real. The epistemic horizon allows for the complete illusion of free will. So you are predictable, and not technically free of causal relationships. But only over a short period of time, and by that, I mean, a subjective estimate of how someone will immediately react (so long you have enough information about said person and the stimuli they will receive) (also emphasis on estimate). The quantum probability and time branching means that the future is not deterministic. Everything is still probabilistic, but there are simply things that are more likely to happen that others. So there isn't free will, but the future is still random. It's just not up to your decisions on how things pan out in your reality.
To sum up: no. There isn't such a free will. It's an illusion caused by being human. But we should continue to pretend for ethical reasons, the fact that the future is still probable, will still exists, and I am not one to advocate anarchy.