Contingency and God’s foreknowledge, contingency and necessity.
Aristotle discusses the question in his On Interpretation when he states that “A sea-fight must either take place to-morrow or not, but it is not necessary that it should take place to-morrow, neither is it necessary that it should not take place, yet it is necessary that it either should or should not take place to-morrow. Since propositions correspond with facts, it is evident that when in future events there is a real alternative, and a potentiality in contrary directions, the corresponding affirmation and denial have the same character. This is the case with regard to that which is not always existent or not always nonexistent. One of the two propositions in such instances must be true and the other false, but we cannot say determinately that this or that is false, but must leave the alternative undecided.”
It is, in this case, necessary that one of two contraries happen, but neither is necessary as it is in itself. It is simply the law of contradiction (or of non-contradiction, if you prefer) at work in time.
We read in the Paradiso that “Contingency, whose action is confined to the few pages of the world of matter, is fully drawn in the Eternal Mind; but it no more derives necessity from being so drawn than a ship dropping down the water derives its motion from a watcher’s eye.”
At first I am unsure of how to take this verse. There are, after all, not just contingency and foreknowledge, but predestination separately. Of course, we do not say that God’s knowledge of something forces it, in the same way that my having already watched a movie or read a book makes me suddenly it’s author just because I know beforehand what will happen the second time I watch or read it. It is, of course, merely that I have seen the story already. God, of course, sees the story all at once, and this, on its own, in no way makes Him its cause.
God has seen already a much broader picture. We know that there will either be or not be a battle tomorrow. Guessing correctly doesn’t necessitate it. In fact, if the battle happens today, it wasn’t necessary yesterday that it happen. God, of course, knew it would, but that did not necessitate it. And, of course, I dare not limit God’s foreknowledge to merely future contraries, but His knowledge extends to all events whatsoever.
However, there is also the fact that everything receives its being from God, to include the being of its very acts (and, if rational, the being of its thoughts and its willing). So while the foreknowledge of God certainly is not causal, understood AS foreknowledge, the fact that God is the prime mover certainly is causal.
This, to me, has always been the more difficult question. It is, however, a question that can be deeply pondered but must remain a mystery. What we must not do (and it has led to many heresies) is attempt to remove the mystery by emphasizing one aspect of this mystery and removing the other.
There is free will, and God is the ultimate prime mover of “all that is.” There is no sin in seeking to understand this; the sin is in thinking we have arrived at understanding this.
That is, as made clear in Canto XVII, God’s business.