A slightly different (but mostly the same) way of looking at it
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.
Re: A slightly different (but mostly the same) way of looking at it
quote:This is the crux of the argument for people who believe foreknowledge is linked to no free choice. In my opinion, you haven't proved this to be true, because your scenarios silently build this impossibility in.
The reason for my entire scenario was to examine the tightly controlled premises that are necessary for it to be possible to accurately know the future. For it to be possible to know the future with 100% accuracy it follows that the future must be inherently knowable. If it isn't then foreknowledge is not even an option. In my scenario the future is knowable. I am just exploring the ramifications of such a universe. I'm sure that you will agree that it isn't possible to change the past. Right? That means a logical extension of my premise of a knowable future is that ALL future is already known by somebody in that future's future so it's all somebody's history. You probably won't agree with that step though. A lot of people don't. So how about this? Fred builds a robot spy machine that will follow Bill for his entire life. (on a grander scale we could envision a vast army of these things that will record ALL time) He then builds a time machine that is able to retrieve the spy machine from any future time and bring it back to the present. Maybe that's how he can see into the future. Who knows? So now Fred has access to video of every instant of time for the rest of Bill's life (potentially everyone who ever lives life too) This scenario makes all future into recorded history. It is therefore unchangeable. It doesn't matter if Bill (or Tim) are informed about their futures or not. Every action, every choice they will ever make is already recorded. they are effectively living in Fred's past. Same thing would happen if Fred were to travel to the distant future and look at all the past before returning. he knows what everyone will do at every step along their lives. I contend that in such a universe (regardless of whether Fred has actually seen it or not) all actions are mapped out and unchangeable. You will do what you will do and there's not a damn thing you can do to change that. All free will would effectively be illusory. We would all be blissfully unaware that we really have no choice in whatever we do as each decision would feel like our own. Only being informed of those choices ahead of time would destroy the illusion. If Fred truly saw Bill choosing blue then that is recorded history and is unchangeable. he is going to choose blue and there is nothing he can do to change that If this were not the case then you would not be living in a universe in which the future is inherently knowable as Fred's knowledge would be wrong, hence invalidating the premise. Does that seem like a paradox? possibly. It will need a lot more work to determine if it truly is one I think. If it does turn out to generate a genuine paradox then we just answered our question as that would mean that at least one of my premises are invalidated and such a universe is not possible.
quote:If you don't buy that idea, what about my other idea that the multi-universe reality where every decision is made and that such decisions cause branching of into new universes. In that case, free will might be unaffected by foreknowledge.
That is quite possible as an alternative to my scenario, however it is incompatible with my premises. In a branching universe where every decision generates a new branch for each possible decision then everybody has absolute foreknowledge of at least one possible future don't they. A pure guess would guarantee that you got it right for one possible future. However, Fred could not possibly know the future any more. he would just see one potential branch which is utterly worthless as a means of foretelling the future. As you propose, a multi-universe such as this would certainly mean that free will was real and completely unaffected by any individual's foreknowledge but that is because true foreknowledge would be impossible in that multiverse. The best you could do would be to attempt to make the future match your prediction by coercing or persuading others to make choices compatible with your vision of the future. Lots of people do that all the time now.