I allow for the possibility of quantum indeterminancies as mentioned by JWood, but these don't somehow magically produce free-will, nor do they necessarily imply uncaused or truly random behavior at the quantum level, but merely behavior far beyond our current ability to predict.
I was not saying that the quantum indeterminancies "prove" free will as a part of human existence. I was just saying that they do not deny the possibility of it.
To some people, the fact that we are debating free will here would seem to imply it's existence.
Terry's point that actually a lot of life activity that we might "call free will" may not really be is a good one. But for some things we really can make an intelligent choice that is not predetermined. For some other things, we may just be mentally "rolling the dice", but that again is not really a mechanistic pre-determinism.