The following entry draws heavily upon W. Matthews Grant, "Divine Simplicity, Contingent Truths, and Extrinsic Models of Divine Knowing," Faith and Philosophy, vol. 29, no. 3, July 2012, pp. 254-274.
It also bears upon my discussion with Professor Dale Tuggy. He holds that God is a being among beings. I deny that God is a being among beings, holding instead that God is Being itself. This is not to deny that God is; but it does entail affirming that God is in a radically unique way distinct from the way creatures are. We can call this radically unique way or mode of Being, simplicity. So my denial, and Dale's affirmation, that God is a being among beings is logically equivalent to my affirming, and Dale's denying, the doctrine of divine simplicity.
A particularly vexing problem for defenders of the doctrine of divine simplicity (DDS) is to explain how an ontologically simple God could know contingent truths.
The problem may be cast in the mold of an aporetic tetrad:
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.
The plausibility of (3) may be appreciated as follows. Whatever else knowledge is, it is plausibly regarded as a species of true belief. A belief is an intrinsic state of a subject. Moreover, beliefs are individuated by their contents: beliefs or believings with different contents are different beliefs or believings. It cannot be that one and the same act of believing has different contents at different times or in different possible worlds.
That the tetrad is inconsistent can be seen as follows. Suppose God, who knows everything there is to be known, 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. But then t is necessarily true. This contradicts (2) according to which t is contingent.
Opponents of the divine simplicity will turn the tetrad into an argument against (1). They will argue from the conjunction of (2) & (3) & (4) to the negation of (1). The classical theist, however, accepts (1), (2), and (4). If he is to solve the tetrad, he needs to find a way to reject (3). He needs to find a way to reject the idea that when a knower knows something, there is, intrinsic to the knower, some mediating item that is individuated by the object known.
So consider an externalist conception of knowledge. I see a cat and seeing it I know it -- that it is and what it is. Now the cat is not in my head; but it could be in my mind on an externalist theory of mind. My awareness of the cat somehow 'bodily' includes the cat, the whole cat, all 25 lbs of him, fur, dander, and all. Knowledge is immediate, not mediated by sense data, representations, mental acts, occurrent believings, or any other sort of epistemic intermediary or deputy. Seeing a cat, I see the cat itself directly, not indirectly via some other items that I see directly such as an Husserlian noema, a Castanedan ontological guise, a Meinongian incomplete object, or any other sort of merely intentional object. On this sort of scheme, the mind is not a container, hence has no contents in the strict sense of this term. The mind is directly at the things themselves.
If this externalism is coherent, then then we can say of God's knowledge that it does not involve any intrinsic states of God that would be different were God to know different things than he does know. For example, God knows that I have two cats. That I have two cats is an actual, but contingent fact. If God's knowledge of this fact were mediated by an item intrinsic to God, a mental act say, an item individuated by its accusative, then given the divine simplicity, this item could not be distinct from God with the consequence that the act and its accusative would be necessary. This consequence is blocked if there is nothing intrinsic to God whereby he knows that I have two cats.
We will have to take a closer look at externalism. But if it is coherent, then the aporetic tetrad can be solved by rejecting (3).