Yes, impossible if our choices are the end result of physically determined chains of events.
No Alan, my argument has nothing whatsoever to do with the physical. Either you make choices entirely because of pre-existing reasons, or you don't. That must be the case whatever pixie dust you try to introduce into the process.
But the freedom I have to compose this post aptly demonstrates that there is something more than mere physical causes...
It demonstrates nothing of the sort.
...because I have no control over physically pre defined cause and effect, but I do have conscious control over what I am currently writing.
You have given no reason (apart from incredulity and trying to redefine the word 'control') why a physical system can't have conscious control.
Where do you suppose this conscious control emanates from?
Your brain.
And remember that a material brain will be entirely controlled by physically pre defined chains of cause and effect.
That is just silly. The chains of cuase and effect are how the brain works, they aren't separate and external to it.
Once again, as you keep ignoring or misrepresenting it, no matter how your mind works or what it's made of, it can't make a choice that is not entirely due to pre-existing reasons (not 'predetermined') without introducing something that isn't due to pre-existing reasons (randomness).
It's impossible because of logic, not physics.