Usually I don’t have a huge interest in philosophical wrangling over divine attributes. It’s easy to find all kinds of paradoxes concerning omni-whatsit attributes of God, but then again, I figure a determined philosopher can always fix these by restricting the omni-whatsitness of God in appropriate ways.
For example, omniscience is a hard idea to make sense of. There is no such thing as a set of all truths, so “knowing absolutely everything” has to be understood differently. And by the time we ask questions like whether God can know by acquaintance what it is to be guilty of a crime, the whole idea of omniscience turns into a massive headache. Still, it might just about make sense to talk of someone knowing all possible facts about the universe, say.
Even so, omniscience is puzzling. Presumably divine knowledge is 100% certain knowledge, not subject to error. But how could God be certain about his own infallibility? I imagine an answer might be that God knows directly, in an unmediated fashion, without having to reason or perceive. He has instant and total awareness of all facts about the universefacts that are, after all, facts only because God has willed them to be so.
But that doesn’t quite solve the problem of divine certainty, even if we accept this very odd form of knowledge. After all, how does God know that this direct, unmediated knowledge is in fact infallible? We start talking about divine self-knowledge, introduce some nasty self-referential paradoxes, and thereby depart from the restricted sense of knowing everything that might avoid problems with the intelligibility of omniscience. Perhaps it is somehow impossiblelogically impossiblefor God to be mistaken about facts. I can’t see how this could be so. That argument is asking for at least the same sort of trouble that sinks ontological arguments, and maybe even more.
None of this would mean a restricted-omniscient God is impossible. You could, I guess, have an entity who was, as a matter of fact, infallibly correct about all facts, and hence, as a matter of fact, correct in its self-assessment of certainty. But that would still be a strangely unwarranted form of certainty.
All right, now I do have a headache. I’m not even sure why anyone should care about all this.