Suppose that our minds operate through some quantum principle, and quantum physicists and cognitive scientists agree that choice is made probabilistically based on situational/environmental and psychological/memory constraints, can we still say that free will exists?
I don’t agree with the supposition. Even if we accept probablism, not every choice involves morality.
I choose to respond in this thread, no? I was looking at the various topics in GD, and noted yours. I saw the interesting title. I then went off and downloaded some FAL build guides, got a cup of coffee, and came back to my desk. I then decided to grace this thread with my wisdom.
I could have decided, and thought about decided to (?), keeping on in my hunt for FAL knowledge. But I weighed the ‘value’ of participating in this thread vs. googling for info, and decided to participate.
Or thats how I see it, at least.
My choices were limited by:
*My situation. (I am at work. If I want to keep my job, I need to stay within certain parameters. No surfing for porn, no sleeping, etc)
*My enviroment. (A cubicle and a nice internet connection. But I do not have access to space flight, so I cannot (realistically) choose to visit the moon, or perform (safe) open heart surgery, etc, due to, among other things, my current enviroment).
*My psychological constraints are legion, but beyond the scope of this topic!
*Memory. I have pleasant memories of reading posts here. That is why I keep coming back. I also have pleasent memories of coffee, which is why I decided to get some coffee first.
But probablism didn’t enter into it. I made no moral judgement in responding. I saw no morally competing choice to this, only other moral-neutral choices. Of my own free will, I responded to your thread.
So we have free will, if only at SDMB? 
(Of course, I could be wildly missunderstanding the OP. If that is the case, set me on the right path…)