BV shows the following are inconsistent:
1. God is simple: there is nothing intrinsic to God that is distinct from God.
2. God knows some contingent truths.
3. Necessarily, if God knows some truth t, then (i) there an item intrinsic to God such as a mental act or a belief state (ii) whereby God knows t.
4. God exists necessarily.
Because:
Suppose God… knows some contingent truth t. He knows, for example, that I have two cats. It follows from (3) that there is some item intrinsic to God such as a belief state whereby God knows t. Given (1), this state, as intrinsic to God, is not distinct from God. Given (4), the state whereby God knows t exists necessarily. For, necessarily, if x = y, and x is a necessary being, then y is a necessary being. But then t is necessarily true. This contradicts (2) according to which t is contingent.
I think I know the response STA would give, but it will be unacceptable to anyone who sees possibility as a feature of possible worlds.
For STA real possibility is a feature of what can be otherwise, which assumes some later time in which it can be otherwise. So long as we consider a thing as within a “now” that prescinds from any later state, we consider it in a way that cuts it off from what it requires to be contingent, thereby making it necessary. This is why STA claims that “Socrates sits” is necessary when he is sitting. So if God sees all things in an eternal now he sees them in a way in which the contingent and necessary are not opposed. Vallicella’s t is therefore both a necessary and contingent truth,* making the tetrad is consistent.
This account of real possibility requires that we see it as a modality of time, and the PW account of possibility will not allow for this. There is no clock for all possible worlds that can allow ‘Socrates sits” to be present in all of them at the moment he is sitting. Whether it’s more reasonable to take this as a critique of PW’s or as a critique of classical theism is something I don’t know enough about PW’s to argue to any conclusion.
*Specifically, it’s a contingent truth known in a mode that makes it necessary, and part of inerrancy would be the ability to distinguish what belonged to the claim as temporally located from what belonged to it from the mode of knowing; just as for those of us who see possibility as a temporal modality assert the same thing about the claim “Socrates sits” when we consider it in a certain way, i.e. as prescinding from any later time.
Just Thomism 
David said,
April 5, 2017 at 4:38 pm
“For STA real possibility is a feature of what can be otherwise, which assumes some later time in which it can be otherwise”
Could you expand a little on this? The way I phrase contingency is that which could have been otherwise, and I’m wondering if the two ways of saying it are really the same.
But I also think of this question in terms of events, but you seem to formulate it in terms of propositions or things.
David said,
April 5, 2017 at 4:46 pm
I think I answered my own question by thinking about it a little longer. “What could have been otherwise” is just saying that back when it could have been otherwise, there was a future time at which it could have been otherwise. And I’m thinking of the event at which it becomes true, not the proposition that it is true.
James Chastek said,
April 5, 2017 at 5:55 pm
Right. Contingency for STA exists only in the earlier/later relation, whether this is past- present or present-future. In fact I first wrote the post saying that contingency was relative to the future but went back and changed it to “later” for the reason you’re seeing.
dmt117 said,
April 6, 2017 at 5:37 am
Can we put this way? God knows eternally that Socrates will be sitting at time t(1) and standing at time t(2), and he knows both in the same simple act of knowing?
James Chastek said,
April 6, 2017 at 6:52 am
Yes, and any truth known by God is necessarily its mode; sitting is necessary even to us so far as we consider (1) only and contingent if we consider it in relation to (2).
My own theory is that the eternal now is meant to combine the claims that (a) God sees all things when they happen and (b) he sees all things in one act. If you want to speak of God knowing something “before it happens” the “before” can’t me meant to give God a temporally posterior perspective. All acts of seeing occur when the thing happens.
God sees all things at once, but there is no one time at which all temporal things happen. I have no theory on God telling the future in exact detail, but tend to think there is an unseen contradiction in such an action.