God knows some things that He might not have known. For example, He knows you and me. Of course He would always have known us at least as possible beings, but He need not have known as actually existing beings. If He had not created us, He would not have known us as actual beings; but He did, and so He does.
So God knows some things that He might not have known. This is a remarkable thing, which has perhaps not been sufficiently pondered among perennial philosophers. It might seem at first to destroy the assertion that God is Actus Purus, pure act. Surely, one might think, if God knows something that He might not have known, then He must have had a potentiality to know this thing, and this potentiality must have been realised, so that He now knows it. But of course this is impossible.
Why do these things that God knows, but which He might not have known, not introduce potentiality and the realisation of potentiality into God? It is because none of these things that He knows but might not have known – for example, no creature – goes to constitute God’s own act of knowledge; no creature ‘shapes’ the divine act of understanding, making it to be like this rather than like that. To use the technical phrase, nothing other than God is the specifying object of God’s act of knowledge. Creatures are real objects of His knowledge; God really knows you and me, not just an idea of you and me. But we are not the specifying objects of the one, eternal, simple, divine act of understanding. We are secondary objects of the divine knowledge. The only specifying object of the divine act of understanding is God’s own essence.
What brings it about that God knows certain objects that He might not have known? In the case of real beings, such as you and me, the answer is simple. It is because He wills to create and sustain us. The divine will, or the divine initiative if you like, brings it about that He knows us. Because He wills to create, His eternal, simple act of knowledge is not only a knowledge of Himself but also a knowledge of us. But it is important to notice that it is not the fact that His knowledge of us is the result of His free initiative which explains why His knowledge of us is not the realisation of a potentiality in Himself. We also can take an initiative and come to know things that we need not have known. For example, I can choose to learn Spanish. But however free this initiative may have been on may part, my learning of Spanish will necessarily be an actualisation of potentiality within me. Likewise, it is not the fact of the divine initiative in creating which is the formal reason why His knowledge of us is not a realisation of potentiality, but simply the fact that we are not the specifying object of His act of knowledge.
Now, what about God’s knowledge of sins? Sins also are ‘things’ which God might not have known, since He might not have created free creatures capable of sinning. But He does know them, since He forgives and punishes them. Sins are, like creatures, ‘secondary objects’ of the divine knowledge. So how does a given sin, for example the fall of Lucifer, or the sin of Adam, become a secondary object of the divine knowledge? A priori, there seem to be two possibilities. Either it becomes such an object because of God’s initiative of choosing to create a world of which it will certainly be a feature, or it becomes such an object in virtue of the creature’s initiative.
Does this latter alternative introduce passivity, that is potentiality and the realisation of potentiality, into God? Only if the formal reason why God’s knowledge of things which He might not have known is His having the first initiative in their coming about. But as I have argued in the last paragraph but one, this is not so. The formal reason why God’s knowledge of such things introduces no passivity into God is that they are not the specifying object of His act of understanding. So if we posit that Adam’s fall becomes an object of divine knowledge not because God chose to create that universe in which Adam would fall, but simply because Adam did in fact fall, we thereby introduce no passivity into God. Of course there are other things to be said about the causal relation between the first mover and creaturely free will. But this is enough for one post.