Suppose I end up at a concentration camp for a significant amount of time. Here are some possible moral development outcomes:
- becoming really bad (e.g., informer, kapo)
- becoming heroically good (e.g., Viktor Frankl, Maximilian Kolbe)
- becoming bitter
- remaining non-bitter
Now, I think we have no reason to think that A's outnumber B's. (It would be great to have empirical data.) Moreover, the average A is less morally bad than the average B is morally good. The reason is that there is an asymmetry here: the pressures that A's and B's are under in the camp decrease the culpability of typical A's but increase the praiseworthiness of typical B's. (There will be partial exceptions, like maybe the person who becomes needlessly cruel or the person who becomes virtuous because he's St Maximilian's cellmate. But even these exceptions are not going to be complete exceptions.) Furthermore—and again data would help—I suspect that some of the A's repent of their badness afterwards (some never do, and for some there is no afterwards), while few of the B's repent of their goodness afterwards. So, if all we know about x is that he is going to be an A or a B, the expected value of x's moral development hange will be positive.
What about the C's and D's? This is, I think, the really important case, as they'll probably be a larger group than the A's and B's. Now, it is a much greater virtue to remain non-bitter through a concentration camp than it is a vice to become bitter through the concentration camp. Part of the reason is the culpability point from the previous paragraph. Making one bitter is the "natural" tendency of horrors, and it is not a great vice to fall into that. So, unless there are way more C's than D's, we have positive expected value of moral development.
Now, add the following thesis: In terms of value, a moderate amount of positive moral development trumps a very large amount of suffering. (Socrates would say—and I think he'd be right—that any amount of positive moral development trumps any amount of suffering.) If this thesis is right, even when we add the amount of suffering, we may still have positive expected value for a random individual who suffers horrors like those of a concentration camp.
The real problem of evil, I think, is not about expected values, utilities and the like, however. The real problem is deontological. Does God have the right to allow someone to suffer so much given the expected value of moral development? I think the answer is positive. Suppose I knew that by preventing a great suffering to myself I would be losing an opportunity for significant positive moral development. Would prudence permit me to refrain from preventing the suffering? I think it would. Nor would such a refraining from prevention be morally wrong. But God is closer to me than I myself am, in some relevant sense. If I would not be imprudent or immoral to permit a suffering to myself, it would likewise not be wrong of God to permit it to me.