Can God Know the Future ?

Anything that does not involve a contradiction in terms may be counted among those possibilities in respect to which God is called omnipotent. On the other hand anything that implies a contradiction does not fall within the aegis of divine omnipotence, because it is not a possibility. Therefore we ought rather to say that such things cannot be done, than that God cannot do them.
- St. Thomas Aquinas, Summa Theologica (paraphrased from A.C. Pegis, Introduction to St. Thomas Aquinas, 1948)

Can anyone know the future? Can God know the future?

If some person or being can really know in advance what my choices will be, then I am not free and really have no choices at all. Suppose Sister Claire, the famous clairvoyant, knows that tomorrow I will steal a red Corvette from Dave's Used Car lot. Now, tonight, I might worry and wonder and try to decide whether to steal the car tomorrow or not. But this would be silly. For if Sister Claire knows I will steal it, then I am not free not to steal it. And if she knows I won't, then I am not free to steal it. If someone knows something, it must be true and cannot be false. So I have no choice. And if I have no choice, it's not up to me. I am therefore not a free moral agent, and so I have no moral responsibility. I cannot be blamed or praised for my "choices" and actions.

But we do blame each other for such things as stealing cars and telling lies and we praise one another for saving lives and being generous. We believe people are free and responsible for what they do. So we must conclude that Sister Claire cannot know what I will do. Furthermore it cannot be known at all what any free person will do. The future, in so far as it depends upon human choices, cannot be known. Knowing what people's choices will be, in advance, is like a square circle, then. It cannot be done without denying that people are responsible for their actions and choices. So not even God can know the future. Saying that He could is like saying that He could make a square circle-nonsense

St. Thomas points out that it is not blasphemous to say that, for example, God cannot make a square circle. For the failure is not God's, but in whoever says "square circle," which is a contradiction in terms--in other words, just a noise. It detracts not a bit from God's true power that He cannot perform logical impossibilities.

Given that insight, let us ask whether God can know what human choices will be, in advance. In other words: Can God know the future?

Bibliography

Copleston, F.C. Aquinas, Penguin Books, Inc., Baltimore, 1955.

Pegis, Anton C, (editor) Introduction to St. Thomas Aquinas, The Modern Library, New York, 1948.