Does God know everything that will happen? If so, how?
 FROM the foregoing it is already somewhat evident that from eternity God has had unerring knowledge of singular contingencies, and that nevertheless they cease not to be contingent.
 For contingency is not incompatible with certainty of knowledge except in so far as it is future, and not as it is present. Because a contingency, while future, may not be; so that the knowledge of one who thinks it will be, may be wrong, and it will be wrong if what he thinks will be, will not be. From the moment however that it is, for the time being it cannot not-be: although it may not be in the future, but this affects the contingency, not as present but as future. Hence sense loses nothing of its certainty when it sees that a man is running, although this statement is contingent.
Accordingly all knowledge that bears on a contingency as present, can be certain. Now the vision of the divine intellect from eternity sees each thing that happens in time as though it were present, as we have shown above. Therefore it follows that nothing prevents God having unerring knowledge of contingencies from eternity.
Notes I might have abridged this paragraph but left it to show how careful Thomas was. All the rigor of any modern mathematical theorem. Like I’ve said before, I also enjoy the way our saint eases us into problems.
 Again. The contingent differs from the necessary according as each is in its cause: for the contingent is in its cause in such a way that it may not result, or may result therefrom: whereas the necessary cannot but result from its cause. But according as each of them is in itself, they differ not as to being, on which the true is founded: because there is not in the contingent, considered as it is in itself, being and not-being, but only being, although it is possible for the contingent not to be in the future. Now the divine intellect knows things from eternity, not only as to the being which they have in their causes, but also as to the being which they have in themselves. Therefore nothing prevents it having eternal and unerring knowledge of contingencies.
Notes Don’t forget that eternal does not mean “starting at some point in the dim and forgotten past and looking forward into the misty future” but instead as “outside of time.” The analogy, imperfect as all analogies are, is looking down from on high onto the timeline of history.
 Moreover. Even as the effect follows certainly from a necessary cause, so does it from a complete contingent cause unless it be hindered. Now, since God knows all things, as was proved above, He knows not only the causes of contingencies, but also that which may possibly hinder them. Therefore He knows certainly whether contingencies be or not.
 Again. An effect does not happen to exceed its cause; but sometimes it falls short of it. Hence, since in us knowledge is caused from things, it happens at times that we know necessary things, by way not of necessity but of probability. Now, just as with us things are the cause of knowledge, so the divine knowledge is the cause of the things known. Nothing therefore prevents things whereof God has necessary knowledge being contingent in themselves.
Notes Oho! A shout-out to probabilists and statisticians from the man himself. Not only that, he ties, as we should but don’t, probability to knowledge of causes. That point is subtle, so I’ll leave off here. But stick around. Next week I’ll have a paper on this topic.
 Further. An effect cannot be necessary if its cause be contingent, for it would follow that an effect exists after its cause has been removed. Now the ultimate effect has both a proximate and a remote cause. Hence if the proximate cause be contingent, its effect must needs be contingent, even though the remote cause be necessary: thus plants do not necessarily bear fruit–although the motion of the sun is necessary–on account of the contingent intermediate causes. But God’s knowledge, although it is the cause of the things it knows, is nevertheless their remote cause. Wherefore the contingency of the things it knows does not militate with its necessity: since it happens that the intermediate causes are contingent.
Notes Never forget we already know God is the first necessary cause of all.
 Again. God’s knowledge would not be true and perfect, if things happened not in the same way as God knows them to happen. Now God, since He is cognizant of all being, whereof He is the source, knows each effect not only in itself, but also in its relation to every one of its causes. But the relation of contingencies to their proximate causes, is, that they result from them contingently. Therefore God knows that certain things happen and that they happen contingently. Wherefore the certainty and truth of the divine knowledge do not take away the contingency of things.
Notes This immediately follows. The big step comes next.
 It is therefore clear from what has been said how we are to refute the objection gainsaying God’s knowledge of contingencies. For change in that which is subsequent does not argue changeableness in that which precedes: since it happens that contingent ultimate effects result from necessary first causes. Now the things known to God do not precede His knowledge, as is the case with us, but are subsequent thereto. Therefore it does not follow that, if what is known to God be changeable, His knowledge can err or in any way be changeable. It will therefore be a fallacy of consequence if, because our knowledge of changeable things is changeable, we think that this happens in all knowledge…
Notes And here we see that Pinnock (see last week) and others cannot be right that God can be “surprised” by future events. The future is not “open” in this sense. It is an understandable error to fall into, however. We’re dealing with infinities such as God’s omniscience and omnipotence, which St Thomas was careful in the beginning to say that we could never know. We’re always coming at God on the edges, so to speak. We can never grasp what it’s like out at infinity.
Therefore, “problems”—or, as the Church calls them, mysteries—like the compatibility of free will with an all-powerful all-knowing God cannot be solved by us in any complete sense. The best we can do is create analogical arguments, or even, in some cases, formal technical proofs of associated ideas, but a full understanding must elude us. The best books on this subject are by William Lane Craig: The Only Wise God: The Compatibility of Divine Foreknowledge & Human Freedom, and The Problem of Divine Foreknowledge and Future Contingents from Aristotle to Suarez, and a few others. The first is a semi-popular treatment, and the second an expert treatise. When I get around to it, I’ll review the first.
 Cf. ch. lxiv.
 Ch. lxvi.
 Ch. lxvi.
 Ch. l.
 Cf. ch. lxv.
 Cf. ch. lxiii.: The third . . . p. 133.