The question of whether God’s omniscience can defeat freewill is a very old canard indeed. Boethius brings it up in his Consolation of Philosophy written during the early sixth century. As it happens, Boethius got the answer right when he pointed out that God’s foreknowledge was not causal. Let me flesh this out a bit before moving to a possible limitation to omniscience that might help explain the problem of evil.
Imagine you and I are sitting together having a drink. At time t you make a free choice to ask for a gin and tonic (we assume you have freewill). Before t I cannot know what your choice will be (even if I have a pretty good idea that you like a G&T and don’t much like whisky). However, after t I do know precisely what your choice has been. No one would deny that my knowledge after t could have an effect on your choice at t so freewill is preserved even thought I now occupy a vantage point from which I can know for certain what your choice was.
So far, so uncontroversial. Now, a little after t, I retire to the men’s room. But unknown to me, the toilet cubicle is actually an experimental Chronojohn which whisks me back in time to before t. Thus, I leave the men’s room and see you and I already sitting at the table and behold, you order a gin and tonic. Once again, it seems uncontroversial that my knowledge, now before t, of what you will order is not going to effect your freedom to order what you like. We can agree that mere knowledge cannot remove freewill unless it also leads to some sort of action. Many science fiction authors have suggested that there are laws of time that prevent paradox and so just as I watch myself leave the table to go to the men’s room, I am sucked back through a temporal wormhole to the moment when I should have left the loo in the first place.
Now God, when he sees the universe, sees all of time at once. And he knows that you will choose a G&T because he can watch you do it (of course he also knows you better than me and might have a very good idea what you’ll order but it is not certain except that he has actually seen you do it). God’s act of seeing you choose can no more invalidate your freewill than my act of seeing you choose. Omniscience in this sense cannot effect freewill. Almost all philosophers and theologians would, I understand, agree here.
Let me now take things one step further and suggest an important limit to omniscience. God, I think, cannot know for sure what we would have done if things were different. Why not? Because if he can predict our actions in a counterfactual situation that would imply a deterministic formula and defeat freewill. Yes, God does have a pretty good idea of what we would have done, but he can’t be certain.
Let’s return to our previous example, forgetting all the time travel stuff. You have, if you recall, just ordered a G&T. The waitress then turns to me and I order a G&T too. Now, God knew I would do this because he could watch me do it from his frame of reference. But suppose you had ordered a whisky. That order might influence my own order because the social option of having the same thing is eliminated (I really don’t want a whisky before dinner). Perhaps then I’d order a beer or a glass of wine. God knows my preferences so would have a good idea what I’d order in this case, but He cannot be certain because that would preclude free choice. Now this, I also suggest, has serious implications for the problem of moral evil because God does not have the kind of perfect information about all probabilities that we often assume he must do. And, if quantum mechanics is truly random, then God might also have less than perfect knowledge about a great deal of the possibilities in the natural world too. He can only know precisely what a universe with a random element will be like by letting it happen. This has implications for the problem of natural suffering. But that it for another time.
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