How about this scenario?
we can start off with a few premises which for the purposes of this exercise are assumed to be true.
Premise 1
Bill and Fred both live in a universe (the same one in case somebody gets pedantic about it) in which it is possible to accurately know the future. The laws that govern this universe are defined such as to make it possible to do so.
Premise 2 Fred has the ability to look into the future if he decides to do so and is never wrong once he has looked at it
Now Bill has to make choice between two colors Red and Blue.
Fred decides to look into the future to see which color Bill chooses. He clearly sees Bill choose Red but doesn't tell Bill.
Given the above premises, is it possible for Bill to choose Blue?
No it isn't. However Bill still thinks that he made a free choice.
What if Fred had told Bill that he would choose Red? Would that change anything? We know that Fred has to be 100% correct since it's one of the premises that we have agreed upon. (taking part in this thought exercise implies acceptance of the premises so no smart comments about not agreeing)
The only way that Bill could choose Blue is if on or other of the premises are invalid but we already accepted them as true for this exercise.
So what does that do to Free will in the first case where Bill doesn't know the outcome, and in the second case where he does?
Another way to look at it is this.
In the above defined universe (where foreknowledge of any event is possible) then all of time must be deterministic and mapped out from start to finish.
If an observer were able to look at this universe from outside he would be able to look at the order of events in any region of time and space.
He could look at it forward, backward or whatever just like we can watch a movie on a DVD player.
This observer could choose to watch any being within the universe from his/her birth to death, then watch it backward then watch it again as may times as he likes. The exact same events would take place in the exact same order each time.
Would it be reasonable to expect different events to take place each time the same lifetime is observed?
If each viewing was different then we have just invalidated the first premise that the future within this universe is knowable with 100% accuracy so it would, by definition, be identical each time the observer watches it.
Just like if you or I watch Sleepless in Seattle over and over. They will always meet up at the top of the Empire State building at the end. The future in their universe is knowable because it's all recorded history from the point of view of an outside observer.
Same thing applies to Fred in our example. Once he sees a future event it becomes (to him) inevitable recorded history. It's already inevitable anyway due to the nature of our hypothetical universe but nobody knows it till Fred looks.
The question is. Do we live in such a universe or not?
If we do then all our choices are mapped out for our entire lives before we are born.
If we don't then the future is never knowable.
It all then comes down to definitions of what free will actually means to you.
My own personal view is that in such a universe there is no such thing as free will. It is all ilusionary.
Do I believe we live in such a universe?
No not really. I don't believe that the future is knowable at all beyond what can be determined by probability.
Edited by PurpleYouko, : typo corrected