Thank you for your question. This is a good one that I had not heard before. If I understand you correctly, you are concerned that the notion of omniscience is not coherent. The reason is that omniscience means knowing everything. However, if a being knows everything, then it knows what it is like to be ignorant of something. However, to do that, such a being would have to have the experience of being ignorant of something, and that in turn requires that it is, or at least has been, ignorant of something--but that contradicts the definition of ignorance! This is, I take it, an epistemological analogue of the Paradox of the Stone, namely the question whether an omnipotent being could do something it is impossible to do (like make an unliftable stone). Someone who wants to defend the coherence of the notion of omniscience might, however, not be convinced that you've raised a compelling objection. The reason is that your objection assumes that to know what ignorance is like, you have to...

I'd like to add one further point to the two made so far. Many contemporary philosophers infer from the so-called Paradox of the Stone that omnipotence is not a matter of being able to do anything, but only a matter of *being able to do anything it is possible to do*. That observation suggests another possible insight. Consider the Problem of Evil. If God exists, then it might seem puzzling that God should permit the extent and kinds of evil that we can find. Now there are many things to say about this, but one pertinent to God's omnipotence is this: Certain moral virtues seem to require some evil, and in such a way that even God can't have one without the other. Even God, it might be remarked, can't make a world in which there is, for instance, forgiveness in the absence of any wrongdoing. (I can't forgive you unless you've wronged me in some way.) This is not to say that all virtues require evil, but just that some seem to, even if you're God. As it happens, contemporary philosophical...