Suppose we assume that
- God exists,
- God is omniscient (i.e., God infallibly knows all of reality as it is),
- The future is causally open (i.e., there are multiple causally possible futures because some future event possibilities are causally undetermined).
Now, suppose a sequence S of events (E1, E2, … , En) plays out a certain way and that some of the events in that sequence are causally undetermined. Prior to those underdetermined events, reality could have gone in a different direction than it in fact did. Suppose, then, that after S God rolls back reality to the beginning of S. Because some of the events in S could have played out differently, there can be no assurance that repeated roll-backs will turn out the same way every time. Hence, it cannot be infallibly known at the beginning of S which specific sequence of events will occur. Thus, it cannot be infallibly known whether S will occur. Hence, there is no specific sequence of events which is such that it will occur. Therefore, the mere fact that, on some occasion, the sequence of events in S does occur, does not suffice to ground infallible foreknowledge that that sequence was going to occur.
Given (a), (b), and (c), therefore, there cannot be infallible foreknowledge of how things are going to play out. A causally open future must, therefore, be epistemically open for God.