Belief Seeking Understanding asks Are Retroactive Prayer Requests Well-Formed? Normally, I would just have answered in his comments, but they seem to be disabled. Douglas seems more inclined toward a negative answer. He says:
Suppose you go to the doctor, and the doctor says "Well, based on everything I know at this point, you either have x or y. X is somewhat of an inconvenience, but y is significantly more serious." Is it foolish to pray "Please God, let it be x and not y?" If y is the consequence of a lifetime of choices, isn't praying such a prayer functionally equivalent to asking God to zap you into some alternate parallel universe where you had x, from another one where you had y?
Then he anticipates my first thought, which was that he was ignoring God's timelessness:
Don't get me wrong, the God of the Bible openly declares that He doesn't live in time but in eternity, and that He is awesome in miracles and working wonders. But on the other hand, it seems to be part of His program that we experience the consequences of our choices.
First, this isn't just about experiencing the consequences of our choices. That's a real issue for prayer regardless of the retroactive element. A friend of mine plagiarized and then had a disciplinary hearing. He didn't know what to pray for, because he knew he deserved bad consequences for it. At the same time, we often pray for things we don't deserve, asking for God's grace. Is that wrong? Even apart from grace, though, we can't ignore all the prayers that have nothing to do with the consequences of our actions. Am I ignoring the consequences of my actions if I pray that my language-delayed son will begin learning to speak more? Am I ignoring the consequences of my actions if I pray that a sermon will speak to me in ways that I need to hear God's voice? Am I ignoring the consequences of my actions if I pray for someone's salvation? The answer has got to be at least "not necessarily". That makes it at least open that retroactive prayers can also be about things that have little to do with the consequences of our actions, even if you don't keep in mind that sometimes praying for grace is just fine.
Second, divine atemporality gives us all we need to understand what's going on with retroactive prayer. If God is not limited to time, then the past for us is just as present for God as our present is. That means God's actions in our past are simultaneous with our prayers as far as God is concerned. If God doesn't need to wait until we pray to know of our prayer, then why is God limited to answering prayers that haven't yet been prayed? For that matter, you don't even need to believe God is outside time to accept this. All that matters is that God has foreknowledge of your prayer. As long as you don't know whether the prayer has been answered, it makes complete sense to pray for something that's already happened.
The problem with the parallel universe statement is that it assumes you're not in the universe where the prayer is answered the way you want. You may well be in the universe with the inconvenient thing rather than the significantly more serious thing. In fact, if God has answered your prayer, then you are. So God wouldn't have to move you to the parallel universe to answer your prayer in that case.
Ah, but isn't it then not worth praying because your prayer has already been answered? Not really. It may well be that the prayer has already been answered because you're now praying. If the reason the prayer is answered is because you do it, then if you didn't do it God might not answer it. It's hard to think about possibility in these cases, mostly because we're thinking of what's possible given something we're stipulating about the past, but we don't normally think in those terms. The same sort of argument about the future is obviously fallacious. There's some fact about what shirt I'm going to wear tomorrow. The fact that the shirt I will wear tomorrow is already there on me in the future does not make my choice to wear it unfree. The reason we don't care about that fact about the future is because for us it's future.
With backward causation and time travel, our view of the situation gets messed with, but the same principles are there. Let's look at time travel first, and then I'll show how the retroactive prayer case comes out ok. If I travel back in time to kill someone whose death would prevent me existing (e.g. my great-grandfather), it just obviously won't work out that way. The reason it won't is because I turned out to exist. That means I didn't end up killing that person. Is it possible for me to kill him when I'm there in that time with the gun loaded and pointed at him? It's possible with respect to the situation at hand. It's possible with respect to the laws of physics and the physical facts of that moment in spacetime. It's not possible, however, with respect to what's already the case about my past. I in fact came to exist because this guy didn't get killed by me. That means I can't really kill him in that sense.
In most situations we'd be fine saying I could kill him even if I turned out not to. That's because all the facts about my not killing him are about the future. In the time travel case, the one fact that makes us think it's impossible is still about the future, but in this case it's also about my past. That's why we have a harder time ignoring this fact about the future the way we do with decisions about what shirt to wear when there's already a fact about what shirt we'll pick. In both cases there's a fact, and given its truth we can't dso otherwise than we will do. Usually we're right to ignore the future when it comes to what we think is possible. In time travel, it's future but past to us, so we have a harder time ignoring it. If we could psycxholgically get over that, we'd realize that I'm as free in the time travel case as in my shirt case.
So what about retroactive prayer? That's got some features in common with time travel and some very different. The thing in common is that some piece of information tells us what will happen, if we happen to know it. The biggest difference is that we don't know it when praying, whereas time traveler me knows his past. So this element of the retroactive prayer case is more like my choice to wear a certain shirt. I don't know which I'll wear when I have the choice to make, just as I don't know if my prayer was granted when I pray retroactively.
Is it possible for my prayer to be answered positively given that the negative answer is true? No. Is it possible for my prayer to be answered ignoring any information about whether the positive answer happened already? Yes. The question is whether it's proper to ignore information about the past if you don't know it. Normally, we assume the past is irrevocable and thus don't try to do something that might change it, simply because we can't. But what if our prayer can genuinely lead to a past decision on God's part? Then it seems it is indeed proper to ignore that there might be facts about the past for the same reason it's proper to avoid facts about the future. What makes it come out the way it did/will hasn't happened yet.
So I have no problem with the idea of retroactive prayer, given that we don't know what has already happened. The arguments against it seem to have the same problems as fatalistic arguments that we can't change the future and thus have no freedom to do anything. This means a sort of backward causation is possible (and indeed, if I'm right, happens all the time). It also means prayer can be much more efficacious than most people have even considered.
For further argument along these lines, see Michael Dummett, "Bringing About the Past", from The Philosophical Review 73 (1964), pp.338-359 and David Lewis, "The Paradoxes of Time Travel", from American Philosophical Quarterly 13 (1976), pp.145-152. Both papers are reprinted as chapters 7 and 8 in The Philosophy of Time, ed. Robin Le Poidevin and Murray MacBeath (1993 in the Oxford Readings in Philosophy series. These are absolutely the best two papers in the philosophy of time. Lewis' is the best time travel discussion in existence, and Dummett's is the best defense of backward causation ever published, though it argues only for a divine route of backward causation and nothing about quantum mechanics, which some more recent authors have tried to do.