(Cross-posted on prosblogion.)
Let's say I climb Mt. Everest, and then enjoy a delightful view from the top. But as I climb the mountain, I undergo various horrendous sufferings. And after I get back down, I have to undergo extremely painful surgery. Suppose that, so far, the overall value assessment is negative. If that's all that is involved, then climb wasn't worth it. The view was nice, and the good of achievement was nice, but, by far, it just wasn't worth it.
But let me add a little more to the story. I did this when I was 20. I am not permanently traumatized by the suffering, and indeed by the time I am 30, my memories of the hideous pains are no longer unpleasant. But I continue to have memories of the beauty of the climb and of the camaraderie, memories of the grandeur of the epic struggle, and these memories continue to be fairly pleasant. Moreover, the feeling of accomplishment, of having overcome the pains, is nice to have. I then live on for fifty more years, continuing to have pleasant memories of that climb.
While the goods achieved at the time of the climb were not worth the suffering, when combined with the value of half a century's worth of memories, even when these memories are not particularly intensely pleasant, they may be worth it. Suppose you say the contrary. Well, then, replace the fifty years with five hundred or five million. Eventually, the cumulative value of enjoying these memories will overshadow the bads which were confined to one decade of one's life (the climb, plus about ten years during which the memories of pain were painful). (This of course reminds one of Parfit's Repugnant Conclusion. But I think there is nothing repugnant here.)
What this shows is that given a long enough life-span, our evaluations of whether some activity was worth doing can change as a result of the values of memories and of retrospective awareness of achievement. Of course, in principle, they can change in either direction. A pain might have been such that it by itself would have been worth it for the sake of an achievement, but if in fact the memories of the pain continue to be painful while the memories of the achievement fade, then it's no longer worth it.
Observe also that while it would be possible to have the pleasure of the memories of having climbed Mt. Everest without having ever had the pains, that pleasure would then be an empty pleasure, and hence either devoid of value or of much lesser value.
Suppose that in fact we live forever. There is no good argument to the contrary that doesn't presuppose the non-existence of God (here we can insert a discussion of arguments for materialism and of arguments against resurrection based on the need for causal continuity), so someone who offers an argument from evil against the existence of God cannot rely on the denial of the claim that we live forever. The above remarks show that remembering over a significant length of time can act as a value-multiplier, and when the length of time is long enough (and in particular when it is infinite), this can completely swamp the original assessment.
Moreover, memory is not the only such effect over an infinite life-span. A small change in character when prolonged over a very long time can make an enormous difference. Suppose that climbing Mt Everest, in my story, made me slightly more considerate. We might well question whether this was worth all the suffering. If I were to live in this more considerate way for five minutes, it perhaps wouldn't be worth it (Socrates will disagree). But again we have value-multiplication--if the difference remains over a sufficiently long interval, the increase in value, summed (actually, integrated) over that time, will swamp the pains of gaining it. In fact, that small difference, over an infinite amount of time, will make for an infinite good. Moreover, if virtue leads to virtue, we might here have compound interest at work.
Of course, God could produce the better character directly and maybe he could induce in us false memories. But the value of that infinite good having been produced in the right way may very well be quite high. (One thinks that the value of a good G's having been produced in the right way is proportionate to the value of G.)
These value-multiplication processes can be selective. Thus, God might very well ensure that our memories of pains not be painful to have (to do that God would need to heal traumas, etc.), while ensuring that our memories of goods be pleasant. Nor would there be anything dishonest in God's doing this. In fact, I think most of us have plenty of memories of pains where the memories aren't themselves painful, and this is no defect in this.
If this is right, then selective value-multiplication processes working in an infinite afterlife might very well, and in quite understandable ways, swamp the kinds of value assessments we get from this-worldly considerations. This possibility, which indeed is not merely a possibility but a fairly high likelihood if God exists, might not entirely undercut inductive arguments from evil, but I think it blunts them quite significantly.
And if one is worried that this undercuts our own reasons to prevent evils, all I can do is point one to this older post of mine.