Bill Keezer's latest post on free will and determinism takes us right to the edge of where such discussions normally bog down: the question of objective indeterminacy (versus a weaker, subjective indeterminacy that merely claims we don't have the means of examining and quantifying micro-events with any precision). I'm a fan of the word indeterminism which, to my mind, is substantively different from words like chaos and randomness. The reason discussions of free will and determinism tend to bog down at about this point—the point at which a pro-free-will philosopher injects Heisenbergian uncertainty into the discussion—is that it's hard to rebut the counter-claim that uncertainty (or randomness, or chaos) is no decent ontological ground on which to base a solid notion of free will.
Another thing that makes a discussion of freedom difficult is that it's conceptually elusive. Freedom, as a notion, is paradoxical: on one hand, it's an exercise of will that takes a being in a particular direction, along a particular path; on the other hand, the word refers to a lack of constraints—to a wide-open range of possibilities because, when your choices have been narrowed down to just one path, there's no choice at all, and that's not anyone's vision of freedom. So: freedom is a weird combination of the narrowly particular and definite and the openly indefinite and unconstrained.* I'm not sure we have the language to describe freedom properly... which is probably why, for many people, the existence or nonexistence of freedom comes down to a matter of belief.
Bill's latest post, which brings in enough hard science to be over my head, is worth a read. I'll be curious to see where his thoughts go next.
*You might object to this explanation by saying that the openness and the constraint aren't at all simultaneous: freedom is the condition that allows for choice, and choice is what happens when you voluntarily narrow your wide array of possibilities to only one path. To choose, then, is to sacrifice the freedom you just had a moment ago. Maybe this objection holds water; maybe not. Personally, when I think of freedom, the notion of choice is intimately tied up with it, not sequentially linked to it.