Roger Olson has recently done a couple of interesting posts about whether or not God can change the past. He argues that God cannot change the past. Here are the links:
Can the Past Be Changed (Even By God)? Some Musings about Time
Follow Up to Musings about Whether the Past Can Be Changed
In the second post he suggests that prayers about the past are probably not effective, and don’t have a Biblical precedent:
And I struggle with why the Bible contains no examples of petitionary prayer about the past at all so far as I know—not even prayers about events not yet known as to their nature and outcome but certain to have happened. This is to me a strong indication that such prayer cannot have any effect other than satisfying some psychological need and causing consternation and confusion.
I agree with Olson that God cannot (or does not) change the past. For example, it does no good to pray that the Holocaust will not have taken place.
Having said that, I do think that prayers about the past can influence what God will have done. I occasionally pray about the recent past. For example, I sometimes pray that a loved one who has been traveling will have made it home safe. I don’t think that God goes back and changes the past because of the prayer, but rather that he will have already done something to have kept them safe because of the prayer. God knows that I will pray later, and can answer that prayer. C.S. Lewis argues for something like this in “Miracles”.
When we are praying about the result, say, of a battle or a medical consultation the thought will often cross our minds that (if only we knew it) the event is already decided one way or the other. I believe this to be no good reason for ceasing our prayers. The event certainly has been decided—in a sense it was decided ‘before all worlds’. But one of the things taken into account in deciding it, and therefore one of the things that really cause it to happen, may be this very prayer that we are now offering. Thus, shocking as it may sound, I conclude that we can at noon become part causes of an event occurring at ten a.m. (Some scientists would find this easier than popular thought does.) The imagination will, no doubt, try to play all sorts of tricks on us at this point. It will ask, ‘Then if I stop praying can God go back and alter what has already happened?’ No. The event has already happened and one of its causes has been the fact that you are asking such questions instead of praying. It will ask, ‘Then if I begin to pray can God go back and alter what has already happened?’ No. The event has already happened and one of its causes is your present prayer. Thus something does really depend on my choice. My free act contributes to the cosmic shape. That contribution is made in eternity or ‘before all worlds’; but my consciousness of contributing reaches me at a particular point in the time-series.
So I agree with Olson that God can’t change the past. But I still think it’s worthwhile to pray about past events, especially events where we don’t know the outcome, and that God hears and can use those prayers.
Side note: Here’s an interesting article about praying for the past by Wesleyan/Nazarene philosopher Kevin Timpe. Prayers for the Past. He calls them PIPs (past-directed impetratory prayers). He argues that PIPs make logical sense for those who hold to Simple Foreknowledge, the Eternal-Now theory (Lewis’ view), or to Molinism. But not for those who hold to Open Theism (because in Open Theism God would at best only have predictive knowledge that someone would pray).
What do you think? Are prayers about the past ever effective?
Wesleyan Arminian 
Timpe’s position appears to be the opposite of Olson’s whose follow up post seems to argue that past directed prayers only make sense within an open theist or a determinist framework but not a framework that combines free will and simple divine foreknowledge.
Timpe’s claim assumes that libertarian free will demands that a choice be incompletely determined in advance. It doesn’t. A choice can be free and completely determined provided it is determined by a former choice that was incompletely determined. That’s why the question “will we have free will in heaven?” can be answered in the affirmative without entailing that sin must be possible in heaven. That is it can be completely determined that we will always choose good and yet we can still be described as free if our fixity in virtue is determined by an earlier choice that was incompletely determined.
Open theism does not demand (as many seem to think) that God can’t know any future event, or even that he can’t know any future choice. One of the things I like about Olson is that he is not an open theist (yet) but he is scrupulous in insisting they be represented fairly.
He argues that Calvinists attack open theism so fiercely because it deprives them of the ability to criticise Arminianism on the grounds that it is inconsistent to combine libertarian freedom will with foreknowledge.
However I note most (?) Calvinists believe Adam had libertarian freedom prior to the fall, whilst still affirming complete divine foreknowledge. This deprives them of the right to claim either that libertarianism is incompatible with complete foreknowledge or that it is incoherent.
“don’t have a Biblical precedent”
Sorta makes it pretty clear that it cannot be claimed to be Biblical don’t it?
True, But the Bible doesn’t explicitly rule out past directed prayers either.
Jesus does say that “your Father knows what you need before you ask him.” (Matt 6:8) Often when we pray for things in the present, for God to answer them he had to be working on the situation already in the past. So that tells us that it’s not logically impossible that God could answer such prayers.
Not Western logic logically impossible, no.
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