1. God is timeless.
2. God is omniscient.
3. A temporal world exists.
are broadly logically inconsistent, as is evident from the necessary truth of
4. If a temporal world exists, then if God is omniscient, God knows tensed facts.
5. If God is timeless, He does not know tensed facts.
Since (2) is essential to theism and (3) is evidently true, (1) must be false.
St. Thomas provides the principles of a response. (N.B. though he is speaking about whether God knows the enunciable and not the tensed, the enunciable is a more general class than “the tensed” and so any proof that God’s knowledge is not the former will show it is not the latter.)
Now just as He knows material things immaterially, and composite things simply, so likewise He knows enunciable things not after the manner of enunciable things, as if in His intellect there were composition or division of enunciations; for He knows each thing by simple intelligence, by understanding the essence of each thing; as if we by the very fact that we understand what man is, were to understand all that can be predicated of man. This, however, does not happen in our intellect, which discourses from one thing to another, forasmuch as the intelligible species represents one thing in such a way as not to represent another. Hence when we understand what man is, we do not forthwith understand other things which belong to him, but we understand them one by one, according to a certain succession. On this account the things we understand as separated, we must reduce to one by way of composition or division, by forming an enunciation. Now the species of the divine intellect, which is God’s essence, suffices to represent all things. Hence by understanding His essence, God knows the essences of all things, and also whatever can be accidental to them.
The implicit distinction in the response is between the mode of knowing and the thing known. Omniscience applies to the things known and not to the way of knowing them, whereas being enunciable is a way of knowing things. Again, omniscience is clearly a response to the question “how much is known?” and not “how is something known?” The claim that God would need to have all modes of knowing would not be the claim that he was omniscient, but rather that he had some unnamed (till now!) property, call it “omnimodalcognitivity”. We have no idea what STA thought of omnimodalcognitivity, but there appear to be insurmountable problems to saying such a thing is possible, still less that it is any perfection deserving of God. God is certainly not omnimodalcognitative since he has no nostrils or antennae, and therefore does not know scents by sniffing them. But at any rate omnimodalcognitivity is simply not omniscience. We can no more say God fails to be omniscient because he lacks this property than we can say that God fails to be omnipotent because he does not lift up a stone with paws.
But what sense can we make of St. Thomas’s argument? Everything hinges on the articulation of God’s unique mode of understanding in opposition to our own way of understanding. Though this mode of knowing is described as “knowing the essence”, this “essence” is taken in the broadest possible sense, namely, “whatever can belong to the thing”. This is clear from the last clause of the response, where “knowledge of essence” explicitly includes knowing whatever could be accidental to a thing (and, a fortiori, whatever accidents a thing actually has, like Craig’s “tense”.) It is better to approach God’s mode of knowing not by focusing on this word “essence” but by seeing what exactly we need to negate in our own mode of knowing when we try to speak of God’s. It seems we need to cut out exactly this feature:
[our intellect] discourses from one thing to another, forasmuch as the intelligible species represents one thing in such a way as not to represent another.
Notice the order of causality: because our understanding is finite, that is, because it does not represent all things at once, we must understand by moving from one thing to another. The successive character of thought follows upon its finitude. If there were some truly infinite act of an intelligence, time would be superfluous and unnecessary for it. An infinite intelligence no more needs time than eagles need binoculars. It’s not just that St. Thomas sees omniscience and atemporality as compatible, he sees omniscience as the making atemporality necessary and temporal existence superfluous to that omniscient being.
David Lewis makes an illuminating distinction that helps us to understand time as a mode of knowing. He notes that if we were to go back a thousand years in time and spend 24 hours there, then we would “spend all of today before today”, though this paradox shows that we would mean two different things by time. We need to divide a.) time as given in the narrative of our consciousness from b.) time as a feature of the world independent from our narrative. God does not need a. to understand b., and he does not need a precisely because he is omniscient – not by having a cluster of finite concepts in need of development, but by having a single infinite intelligible procession (the Son) that is adequate to all being, even being in its concretion.