This may have been discussed before but I do not remember reading it in the past. If theists claim god is omniscient, then he knows everything, including our thoughts and what will happen, thus free will can not exist. If free will does exist, then god can not be omniscient. Discuss

Or is this just another form of the omniscience paradox because the definition of free will in itself would supersede omniscience? The same way god not being able to make a square circle does not necessarily mean he wouldn't be all powerful because a square circle is nonsensical?

But is seems to me that the definition of omniscient, forces omniscience or free will to be true, but never both at the same time

Does God 'knowing everything' preclude the endless possibilities that result from Free Will being real?

If he's not omnipotent (and it's not possible to be omnipotent AND omniscient) then he can't stop you making free choices, although he can know see what those choices might be. You have Free will though.

If he's omnipotent, then he's not omniscient so he can't know what all the choices are but has the power to allow you to make choices. So again, you have free Will.

(btw, I'm in the Free Will 101 class. If you want high level discussion of Free Will check out Zumby's thread on Determinism and Free Will)

Well I tend to think if god knows everything it does preclude any possibility of anything other than reality from being possible, thus making free will false.

That may seem a bit nearsighted, but just because he might know of the possibility of choices being possible, he would have to know what choices we would take, making the other possibilities moot

And on your second point, if you say he can't stop us from making free choices, but he knows what the choices will be, then how can we call it free will if it's predetermined

The approach called "open theism" says roughly that god's omniscience extends to all that can be known, but the future can't be known. This preserves the concept of free will while adopting a weaker concept of omniscience. I can imagine this being somewhat attractive, as it makes a lot of sense out of various Bible passages where Yahweh appears not to know what is going to happen, or sets tests for people, or changes his mind about a course of action. If I was a theist this would probably be my favoured approach.

For a decent introduction to the various theological approaches you might want to check out the SEP entry 'Foreknowledge and Free Will'.

Is the 'future can't be known' intended to escape the 'can't be omniscient AND omnipotent' problem?

Because they're not predetermined? In any case, if the future isn't knowable that settles the issue of omniscience causing problems for Free Will.

No it's intended to escape...

I thought that the 'can't be omniscient AND omnipotent' problem was caused by the fact that God's omniscience included being able to see the future but then either not being to change it, or being able to change it in which case he's not omniscient?

As a separate issue from the Free will argument.

Thread is about omniscience vs free will, not omniscience vs omnipotence though innit?

Well yes.... but that issue has been settled and I thought I'd take advantage of you being around. Plus, I thought the issue of omnipotence was relevant if it could be used to show that God can't be omniscient. Innit. (which is the correct use of 'innit'.. )

There is another possibility that allows both omniscience and free will to exist simultaneously. It is based on the fact that time is a dimension which behaves like space in many ways. We are constrained in our movement in time but one could postulate that God is not.

Take this thought experiment. Imagine that you and I are normal human beings and that I possess free will. My future actions are therefore unknowable to you. Now remove your constraint such that you are now able to move through time just as you do through space. All of my future actions are now known to you, but I have not been changed at all in the experiment. Thus I possess free will while you simultaneously have knowledge of all of my future actions.

ICWUDT

but in reality, where you live, you may have free will, but because i know the outcome, would it not be predetermined? if i go back to where time is a constraint i can write down your actions before you do them.

its kind of like an idea about fate that i struggle with. because we live in a time based world, that we can not travel backwards in, how can we say that any actions we take were not our fate? just because we chose to do them is irrelevant. its the fact that we have no way of changing the past that makes me ponder

I stipulated free will while you and I could not travel in time. If you prevent me from stipulating free will in two normal humans without the ability to travel in time, you are saying there is no free will, period. Your OP questioned whether free will and omniscience could both exist. If you will not allow the existence of free will in the absence of omniscience, then your OP becomes trivial. Obviously if free will cannot exist then free will and omniscience cannot coexist.

We are taking two ill-defined concepts, which little indicates exist, where the majority of explanations for their existence are full of gaping holes. Then we try to shoehorn them into concepts we do know, and discuss the effect they have on eachother.

In short, I think we are doing the philosophical equivalent of debating who wins a cagematch between a unicorn and a chimera.

How is this different from your using a concept that we don't really understand and might not exist (causality) in conjunction with another concept we don't really understand and might not exist (consciousness) and using them to deny free will?

The chimera hands down. You start with a lion (one of nature's top predators), add a venomous snake in place of a tail and toss in the ability to breathe fire. On the other side you start with a horse, a herbivore that essentially runs from predators. Then you put a horn on his head but put them both in a cage so that the horse's speed is negated.

How is this even close?

But a unicorn is magical and the horn powerful.

On the topic of the OP, however, I always imagined it as RLK explained.

The ability to "move through time" seems to suggest that what happens in the future is fixed, which would contradict the free will postulate.

i know my mom will go to work tomorrow
i made her go to work

XD
makes no sense

Not really. One must discuss these concepts very carefully because time is built into our language. If I say that the charge on the electron is "fixed" it means that it is unchanging. Unchanging how? Unchanging in time. If it varied with time then it would not be "fixed". But the future is a point in time. To say it is fixed means what? If I can travel in time and I go to the future, return to the present and then go to the future again, what orders those two appearences in the future. Time orders events in our perception but that no longer works when I am moving in time. Thus "fixed" in that context has no meaning or at least the meaning has to be completely reconstructed.

In my example I stipulated that I have free will. You must allow that if you are going to demonstrate that free will and omniscience are incompatible. If I grant you the ability to move through time, does that somehow remove my property of free will? How does that work?

Much of modern physics makes no sense if judged by its ability to be expressed in colloquial language. A photon flies towards two slits. It passes through only one slit or it passes through both slits. Well it passes through both if you do not look but if you check it only passes through one. But that occurs even if your detector is located after the barrier.

Makes no sense.

The question is whether the future already exists. So, let's say you have the ability to move forward and backwards through time. So you go to the Sunday and find out that I freely decide to have pancakes for breakfast. Now, it is true that you don't merely by observing me cause me to choose to have pancakes for breakfast. So I'm not claiming that by time-traveling you are somehow affecting whether I have free will or decide to have pancakes. Rather, my claim is that the idea of time travel of the kind that would give someone knowledge of future events is incompatible with your free will postulate.

In other words, until I actually make the free decision to have pancakes on Sunday there is no fact of the matter about what I do. This is because the future is created in part by my decisions which are made at the time they are made and are not dependent on antecedent conditions. Thus, if you travel to the future to see what I have for breakfast on Sunday, there is nothing there to see because there is no future except in the future.

Another way of putting it is that without determinism there isn't a time line on which to travel.

Also, just as an epistemological matter, I don't think thought experiments that involve time travel tell us anything useful. Our intuitions about time are not particularly accurate.

Feynman's treatment of the double slit experiment in The Feynman Lectures on Physics Vol III is still one of the best things I've ever read (and not really understood)

I'm sure this could be formalized into a general principle/heuristic for thought experiments. If this idea is your own it might be worth putting into print or w/e. Just my 2p.