What Is Omniscience?

The Definition and the Problem

Omniscience is the divine attribute of knowing all truths. That is the short version, and it is accurate as far as it goes. Aquinas put it that God knows all things — not by gathering information, the way we do, but by knowing creation in knowing the divine essence itself. God does not learn. God is not surprised. Every fact, every possibility, every actual state of affairs is present to the divine mind. As one of the core attributes of God, omniscience sits alongside omnipotence and perfect goodness, and it is nearly as old. Augustine treated God's exhaustive knowledge as basic to theism. Anselm assumed it. The classical tradition simply took it for granted that if God exists, God knows everything.

The problem arrives the moment you connect omniscience to free will. If God knows, right now, that you will choose the salad over the steak at dinner tomorrow, then it is true that you will choose the salad. And if it is already true — if it was true before you were born — then how can your choice be free? You cannot choose the steak, because that would make God's knowledge false, and God's knowledge cannot be false. So your future is settled, and settled before you arrived at it. The worry is not just about dinner. It is about every moral choice, every act of love, every act of betrayal. If omniscience and foreknowledge fix the future, then freedom seems to be an illusion, and with it, moral responsibility.

This is the foreknowledge problem, and it is one of the most persistent puzzles in the philosophy of religion. It has been generating solutions — and generating new problems with those solutions — for over fifteen hundred years.

The Timelessness Solution

The first major answer came from Boethius, writing in the sixth century, and Aquinas adopted and refined it. The key move is to deny that God's knowledge is foreknowledge in the temporal sense. God is not sitting at an earlier moment, looking ahead to a later one. God is outside time altogether. God exists in an eternal present — a single, unchanging now — and the whole sweep of history is present to God at once. God does not foresee your dinner choice the way a weather forecaster predicts rain. God sees it, directly, because for God it is present.

On this account, divine knowledge does not cause the future. It does not settle it ahead of time. It simply apprehends what is, from a vantage point that includes all times. The analogy Boethius used is of a traveler on a road: the person standing on a hill can see the whole road at once, while the traveler sees only what is ahead. The person on the hill is not causing the traveler's path; they are just seeing it. So God, from the standpoint of eternity, sees the whole temporal order, and God's seeing does not necessitate what is seen.

This is elegant, and it has been the dominant Catholic and many Protestant position for centuries. But it has costs. It requires the timeless view of divine eternity, which not everyone accepts. If God is inside time, as some philosophers argue, then the analogy breaks. And even if God is outside time, there is a residual worry: if God's knowledge is infallible, then the future is still fixed, even if it is not fixed by God's knowing. The freedom of the creature seems threatened not by causation but by the bare fact of infallible foreknowledge. If it is already true that you will choose the salad, your freedom looks compromised, regardless of what caused the truth.

Molina and Middle Knowledge

The most ambitious solution to the foreknowledge problem came from Luis de Molina, a sixteenth-century Jesuit, and it has had a remarkable revival in contemporary philosophy of religion. Molina introduced the concept of "middle knowledge" — knowledge that stands between God's natural knowledge (of all possibilities) and God's free knowledge (of what actually happens).

Here is the idea. God knows all the things that could happen — all the possible worlds, all the possible choices. That is natural knowledge. God also knows what will actually happen — the actual world, the actual sequence of events. That is free knowledge. But between these two, Molina posited, God knows what any free creature would freely do in any possible circumstance. Not what they must do, not what they will do, but what they would do if placed in this situation rather than that one.

The point of middle knowledge is to give God a way to choose which world to actualize without determining the free choices within it. God knows that if Judas were in situation X, he would betray; if in situation Y, he would not. God decides to actualize the world containing situation X, and Judas freely betrays — freely, because middle knowledge does not cause the choice, it merely reports what the creature would do. God's foreknowledge, on this account, is accurate because God knows what the creature would do, and the creature's freedom is preserved because the knowledge is non-causal.

Molinism is powerful, but it faces a serious objection. Is there a fact of the matter about what a free creature would do in a non-actual circumstance? If you would have chosen differently had the menu been different, is that a truth that God can know? Or is it indeterminate — not true or false until it happens? This objection, raised by Robert Adams and others, is the main philosophical fault line in the current debate. Molinists insist that there are true counterfactuals of freedom. Critics insist that there are not, and that positing them is metaphysical overreach.

Simple Foreknowledge

A third approach, simpler than Molina's, holds that God simply knows the future because God is omniscient, and that this knowledge does not compromise freedom because knowledge does not cause what it knows. You know that the sun rose this morning. Your knowing it did not cause the sunrise. Similarly, God knows what you will choose tomorrow, and the knowing does not cause the choosing.

This is clean and has its defenders, but it leaves a gap. The sunrise is a settled fact about the past. Your future choice is not yet settled — or is it? If it is already true that you will choose the salad, then it is settled, and the question is why. Simple foreknowledge does not address the deeper worry that infallible knowledge of a future free act seems to make that act unfree. It helps with the causation objection, but not with the necessity objection. For many philosophers, that is not enough.

Open Theism

The most recent proposal, and the most radical, is open theism. Open theists — including Gregory Boyd, Clark Pinnock, and John Sanders — argue that future free choices are genuinely indeterminate. They are not yet true or false. There is no fact of the matter about what you will choose tomorrow, because your choice has not happened yet, and a free choice is one that could go either way. Therefore God cannot know what you will freely choose tomorrow — not because God is limited, but because there is nothing to know.

This sounds like a limitation on omniscience, and open theists are honest about that. They redefine omniscience as knowing all truths, and they deny that future free choices are truths. If there is no truth about your future free choice, then not knowing it is not a failure of omniscience. God knows everything that is knowable. It is just that future free choices are not knowable — they are open.

The motivation is pastoral and philosophical. Pastoral: open theism makes prayer meaningful in a way that foreknowledge does not. If the future is genuinely open, then prayer can genuinely affect it. Philosophical: open theism preserves libertarian freedom without the contortions of timelessness or middle knowledge. The cost is that it gives up a long-standing commitment of the classical tradition. Augustine and Aquinas assumed that God knows future free choices. Open theism says they were wrong about that, and that the correction preserves what matters most about omniscience — God's complete knowledge of all that is — while making room for a freedom the classical account strained to accommodate.

The debate is not settled. The timelessness solution, Molinism, and open theism all have sophisticated defenders and serious objections. What is clear is that omniscience, like the other divine attributes, is not a simple label. It is a concept with deep internal structure, and the puzzles it generates — about time, about freedom, about what counts as a truth — are among the most enduring in the philosophy of religion.

Sources

• Stanford Encyclopedia of Philosophy, "Omniscience" — https://plato.stanford.edu/entries/omniscience/
• Stanford Encyclopedia of Philosophy, "Philosophy of Religion" — https://plato.stanford.edu/entries/philosophy-religion/
• Stanford Encyclopedia of Philosophy, "Foreknowledge and Free Will" — https://plato.stanford.edu/entries/foreknowledge/

Related Topics

• What Are the Attributes of God? — the broader divine property cluster.
• What Is Omnipotence? — the companion attribute and its own puzzles.
• Faith vs Reason — how divine knowledge relates to human inquiry.
• Why Is There Suffering? — where omniscience meets the problem of evil.