One of my criticisms of Open Theism is that it makes God a less-than-omniscient being. Now process theologians may have no problem with that, but their cousins the Open Theists may. Typically, they do not want to say God lacks this perfection. Usually, the idea is that God is omniscient because he knows all the truths there are to know (because the future conditionals are unknowable; they lack a truth value).
This line of defense by the Open Theist will seem to many to be dubious. However, there may be some merit to their line of thinking. Consider issues surrounding God’s omnipotence. There are several paradoxes or problems with omnipotence presented. For example, God’s actions and man’s free will. A man cannot be forced to freely do something. The standard line of defense is to claim this is a logical impossibility, and so God cannot be faulted for not being able to achieve this (it is not, strictly speaking, a thing to be achieved). Therefore, God is still omnipotent, for there is no non-logical limit to his power.
Is the same defense not open to the Open Theist? Can she not say that God is still omniscient here, because there is no non-logical limit to his knowledge? At first blush, this seems very promising. But upon further examination, it seems that it all depends on the idea that God’s foreknowledge and future conditionals (or relevantly-free counterfactuals) are incompatible, in a completely logical sense. This will take quite some work to show.
I would argue that if it is even possible for God to have knowledge of future contingents, then any being worthy of the title “God” must necessarily have that knowledge. Essentially, if it is even possible the Open Theist is wrong, then his lack of foreknowledge would be a non-logical limit on his knowledge. Any such conception of God would be inferior in Perfect Being Theology.
There are plenty of good reasons to reject the idea that future contingents and God’s foreknowledge cannot go together (in a logical sense). See William Lane Craig’s The Only Wise God for more on that. Dialectically, Open Theists claim that a traditional understanding of God’s omniscience is faulty because he logically cannot know certain propositions taken for granted under the traditional model. The response is that if it is even possible God does know them, then the Open Theist is wrong. It is therefore up to the Open Theist to overcome the objections made by Craig and construct a positive case for this. If they cannot, it looks for all the world as though they have constructed an inferior god.