Philosophers and theologians have often defined “divine omniscience” as “God’s knowledge of the truth value of all meaningful propositions.” I completely agree with this. Unfortunately, they typically assumed that propositions about what “will” and “will not” occur exhaust the field of meaningful propositions about the future. They thus concluded that God eternal knows all that will and will not take place and that there is nothing else for God to know.
This is a mistake, however, because propositions about what “might and might not” take place are also meaningful, and God must therefore know the truth value of these. Moreover, the opposite of “might” is “will not,” and the opposite of “might not” is “will.” So, if a “might and might not” proposition is true, then the corresponding propositions about what “will” and “will not” take place are both false. For example, if its true that “Greg might and might not buy a blue Honda in 2016,” then its false that “Greg will (certainly) buy a blue Honda in 2016” and false that “Greg will (certainly) not buy a blue Honda in 2016.” So too, if it ever becomes true that “Greg will (certainly) buy a blue Honda in 2016” or true that “Greg will (certainly) not buy a blue Honda in 2016,” then it will be false that “Greg might and might not buy a blue Honda in 2016.” And since God knows the truth value of all propositions, God would know precisely when it is true that I “might and might not” buy this car and when it becomes true that I either “will” or “will not.” God thus faces a partly open future.
This is controversial. Why assume that statements about what “might” happen contradict those about “will not”? It seems this sort of statement is meaningful too: “I could run through the streets naked in the next 5 minutes, but I will not. The “could” here expresses the possibility of those (terrible) states of affairs, and the “will not” expresses that they shall not come to pass, owing to my rational choice. There is nothing contradictory about saying this sort of thing, but the semantic analysis Boyd gives of “might” would make it so. Thus, we have reason to doubt his analysis. Of course, there is a natural reply. I don’t really know that I “will not” run through the streets naked; after all, it could happen. Thus, my claim that these states of affairs “will not” happen is just a form of loose talk; what I really mean to say is that I could run through the streets naked, but that I will almost certainly not. Even if after the 5 minutes passes (and it has, because I got up to make some tea in the middle of writing this post) I cannot say that I really knew that I would not run through the streets naked; I got lucky, because the states of affairs turned out in my favor, making my prediction come true. I have two objections to this reply. First, it seems very odd to think that the truth of my claim about the future was a matter of luck. To suppose so is to assume that claims made on the basis of a high degree of probability cannot really constitute claims of knowledge. Now maybe that’s right: maybe we cannot know that P unless we have eliminated all the evidence that brings our probability judgment less than 1.0. If that’s right, then we don’t know much, and virulent skepticism follows. An omniscience being would then be a skeptical being, one that makes no definitive truth claims with respect to future contingents. How, then, do we make sense of a prophecy where God declares what will be the case with respect to future contingents? We could say that God utters them because he determines the corresponding states of affairs to come to pass, but this only goes so far. For example, Jesus predicts Peter will deny him three times; in order for Christ to know that, God would either have to determine that Peter sins, or Peter’s actions would have to be causally determined by some other process not involving God. But it would be contrary to the incompatibilist assumptions Open Theists like Boyd make about human freedom; Peter is responsible for his actions by virtue of freely denying Christ, meaning Peter could have done otherwise. Second, it does not follow from “P will not occur” that “P must not occur.” That is, knowing that P will not occur does not entail any causal restraints that necessarily entails P’s not coming to pass. We should not confuse the certainty of an outcome with the necessity of an outcome. Let P stand for “I will not run through the streets naked in the next five minutes.” From the premises:
- Necessarily, if anyone knows P, then P.
- God knows P.
It cannot be derived:
- Necessarily, P.
All that follows is:
The sort of reasoning that concludes  is fallacious. This is not to say that Boyd’s analysis doesn’t have its attractions. For starters, it mimics the very famous and widely accepted counterfactual semantics of David Lewis. But the devil is in the details, because Boyd uses the term “might” to connote a sense of freedom that is intuitively at odds with a settled future. But the sort of semantics he appeals to does not use “might” this way, for on those semantics something that “will” happen entails that it “might” happen, which is just to say that something that will happen could happen. This resembles the truism that something is possible if it is actual, yet there is nothing in the analysis that presumes that what is actual is necessary. Boyd knows this, which is why he is careful in this statements to conjoin”might” with “might not” so as to capture the sense of freedom he assumes is incompatible with a settled future. Yet by virtue of that move, he evacuates the intuitive meaning of “might” making it compatible with “will” while further assuming that future contingent ‘will’ and ‘will not’ propositions with respect to creaturely freedom cannot be true. Perhaps that assumption is correct, but it needs to be argued for. The problem I have with that assumption is that it seems to make it impossible for the future to come to pass. It is analytically true that the future will be what will be. On Boyd’s view, it appears that if part of the future might not be, then it is not the case that it will be part of the future. And that, if anything, is unintelligible.
I admit, my understanding of Lewisian counterfactuals is not very clear, so take what I say in the last paragraph with a grain of salt. In any event, these things are worth thinking over even if they will make your head hurt.