For simplicity, I shall ignore the distinction between God talking and Jesus talking. I shall also write "deny" for "deny libertarian-freely" (note: typical libertarians allow for the possibility of free choices that are determined by character and circumstances, as long as the agent had a sufficient role in forming the character through properly indeterministic choices; it is only the latter that I will call "libertarian-free"). Take the case where God tells Peter that Peter will deny him. What divine knowledge was the prophecy based on? Suppose we say: God tells Peter that Peter will deny because God knows that Peter will deny. This would be a simple-foreknowledge (SF) account of prophecy. Now we have an apparent circularity in the order of explanation. God telling Peter that Peter will deny is explanatorily prior ("e-prior") to Peter's denial--it affects Peter's state of mind when choosing whether to deny. But Peter's denial is, presumably, e-prior to God's knowing that Peter will deny. (Thomists and Calvinists will likely deny this. And so such Thomists and Calvinists will have no difficulty.) And God's knowing that Peter will deny is e-prior to the prophecy. So we come full circle.
There is a way out of this argument: God ensures that Peter's choice whether to deny is causally isolated from Peter's memory of the prophecy. This breaks the circle, since then God's prophesying to Peter that Peter will deny will no longer be e-prior to Peter's denial. Moreover, Scripture says that only after the denials did Peter remember the prophecy, so there is some exegetical ground for supposing some causal isolation.
The difficulty with this SF account of prophecy is that it only makes prophecy possible in cases where the prophecy is isolated from the prophesied event. I shall argue that the Molinist may face a similar problem.
Here's why. According to the Molinist, the prophecy is issued not because of God's knowledge that Peter will deny, but, roughly speaking, because of God's knowledge that Peter would deny in C (where C is carefully chosen--see Tom Flint's book for details). Now, take two contingent states of affairs:
- C obtaining and God's knowing that Peter would deny in C
- Peter's denying in C
- If the occurrence of a particular libertarian-free choice A in C necessarily co-occurs with a state of affairs S, then the occurrence of A in C is e-prior or identical to S.
One might try to argue for (3) on the basis of the following plausible principle:
- If p entails that x freely chooses A, then x has or had or will have a choice about whether p.
- If x in choosing A exercises her ability to have a choice whether p, and if p, then x's choosing A is either identical with p's holding, or else x's choosing A is e-prior to p's holding.
If (3) is true, then (2) is e-prior to (1). We can also argue for the e-priority of (2) as follows. Its being the case that Peter would deny in C is e-prior to God's knowing that Peter would deny in C. And (2) is e-prior to its being the case that Peter would deny in C. Why? Because otherwise we cannot explain the odd coincidence that whenever (2) occurs, so does its being the case that Peter would deny in C.
But if (2) is e-prior to (1), then the argument against the SF view applies equally well to the Molinist view. For, (1) will be e-prior to the prophecy, and the prophecy will be e-prior to (2), unless isolation holds.