God is omniscient. He knows everything. He understands the past, present, and future. But if He knows the future, can we have free will? Are we free agents choosing our own path? After all, if God knows what I will do tomorrow, then I have no choice but to do that thing. If I do not, then God was wrong and He is not omniscient. If I do, then His knowledge means I do not have the freedom to do otherwise.Therefore, it seems our free agency is proof that God is not omniscient. The Christian God claims omniscience, so He cannot exist.
This argument, along with The Omnipotence Paradox and The Problem of Evil, is used by atheists to disprove the Christian God, is known as the Omniscience/Free Will Paradox, among other names. The problems with it are sometimes difficult to see because it is not often put into a syllogistic form, but if it were, it would look like this:
(1) A necessary condition for an act’s being free is that it is possible for the agent that is going to perform the act not to perform it.
(2) If God knows that an agent is going to perform an act, then it is not possible that the agent is not going to perform it.
(3) If God knows that an agent is going to perform an act, then it is not the case that that act is free.
(4) If an omniscient God exists, then if an agent is going to perform an act then God knows that that agent is going to perform that act.
(5) If an omniscient God exists, then if an agent is going to perform an act then it is not the case that that agent is going to perform that act freely.
(6) There is an agent that is going to perform an act freely.
(7) It is not the case that an omniscient God exists.
This argument actually fails for many reasons. Here, I mention only a few.
Potential and Actual Futures
The first problem with this argument is the first premise, “...it is possible for the agent that is going to perform the act not to perform it.” This premise claims that it must be possible for the agent to not do what he will do. This is not only a non-sensical premise, but it has nothing to do with whether or not there is an omniscient God.
If a free agent has two choices, choice A or B, then he has two potential futures, based on which of the two choices he chooses. However, one and only one of them will become his actual future. Not only that, but one of them must become his actual future. It is not possible that he does not have an actual future, unless he were to die, in which case it wouldn't matter much anyway.
If I were to see the free agent freely choose choice A, then I travel back in time before he made the choice, then he would still freely choose choice A, but my knowledge does not force him to make that choice. Instead, my knowledge is the effect of his choice, not the cause. The reason he doesn't choose B is not because of my foreknowledge or because he is not free, but because I observed what he will do, not what he could do. That is, I saw the actual future, not a potential future.
So this argument is based on the expectation that one can change the future. It's the expectation that one could not do what he will do. That is a non-sensical statement. It is possible that I not follow one of those potential futures, but it is not possible that I do not follow my actual future, whatever I decide it is. I am free to choose what I will do, but it is not possible that I don't do what I will do. The main premise of this argument, then, is based on a self-contradictory idea.
Incidentally, the existence of an actual future may sound like determinism, but that is not the case. Even in a completely random universe, there would still be an actual future, because even if what will happen in the future has absolutely no connection to the present, one thing is still certain: something will happen. So if God is omniscient, then he would still know the future in an entirely random universe.
Cause and Effect
However, the main claim of this argument is that we are not free to choose for ourselves what we will do in the future because God's knowledge of the future causes us to make the decisions He knows we will make, but whether or not there is an omniscient being has absolutely no effect on whether or not we are free.
Imagine a world in which there is no God. A person in this world would freely make a string of choices throughout their life that determines there future. In this world, the person would have free agency. This world must still have an actual future. By that I mean there are facts about the future. Now, if we were to place an omniscient being in this world who has knowledge of these facts about the future, how does it change anything about those facts? If, in a world without omniscience, you freely choose to eat breakfast, how does the presence of an observer change that fact? Your actual future is your actual future regardless of whether or not there is an omniscient God who knows what that future is. Our actions determine God's foreknowledge and not the other way around, and if we chose differently then God's knowledge would be different.
In the example above, the free agent does not choose A because God knows he'll choose. Rather, God knows he'll choose A because he will choose A. God's knowledge is the effect, not the cause. If the free agent had made different decisions, God's knowledge would have been different.
Perhaps the biggest flaw in this argument is that it assumes that foreknowledge implies causality. This is certainly not the case, since there is no clear difference between a world with an omniscient God and a world without one. Instead, God's knowledge is the effect of our actions, rather than the cause. Therefore, the idea of free will is entirely consistent with the existence of an omniscient God.