I was wondering though how you might respond to the view held by some in the Reformed camp such as Oliphint (I think at least, so don’t hold me to it) and Poythress that God does not think propositionally. I am not sure if they would advocate the contingency of propositions, then, but if you ever have the time, could you explain how the argument might still go through, or if the objection has no effect at all?
It depends on what exactly is meant by “thinking propositionally”. If the claim is that God’s thoughts aren’t dependent on propositions (conceived as truth-bearing abstract entities) that exist externally to God and independently of God, in some kind of self-existent Platonic realm, then I wholeheartedly agree. Welty and I have argued that propositions are divine thoughts, which would rule out that Platonist scenario.
However, if the claim is that God does not think in terms of propositions at all, then I strongly disagree. For that amounts to saying that God does not think in terms of truth and falsity. Propositions are conventionally defined as the primary truth-bearers (see, e.g., the recently revised SEP entry). Propositions are simply those entities that are non-derivatively true or false. If God has any true thoughts then it follows by the very definition of ‘proposition’ that God thinks propositionally. And, of course, God does have true thoughts. (How could God reveal truths to us without first having true thoughts?)