In PofE, I argued that
....there is no reason to believe that this world's innocents would be better off for being spared disproportionate suffering than they are by undergoing it. For in the sort of world where innocents would be spared such suffering, the innocents of this particular world could not have existed at all. Whether innocent or not, we are fragile creatures subject to the mischances of nature and other peoples' failings. In particular, none of us today would have come into being if the sorts of physical and moral evils that cause disproportionate suffering had not contributed to our ancestry. Hence, a world in which suffering precisely matched desert would not be a world in which the actual descendants of the first couple could have existed. Such a world might have contained rational creatures, even humans, but not you and me. Hence, the price of preventing or eliminating the disproportionate suffering of actual human beings would have been denying us existence altogether.
Elliot asks: "How do you differentiate between a person's created essence and his historical reality in this argument?" And the import of that question seems clear, at least to him:
Couldn't I (in essentia) have existed nine hundred years ago in Sweden? If I am, necessarily, a result of a given state of affairs, aren't God's hands tied? Couldn't I have existed in a world in which Hitler never did? If he has to allow certain evils to produce me, then doesn't he have to allow certain diachronic evils to produce the final good? That may be true, but something in it smacks of theistic necessitarianism (not mention anthropological historical determinism). If God always, by nature, wills the greatest good, then it seems he MUST always will the good in a certain way.
To raise such a difficulty is to suppose two things: that (1) my "created essence" is distinct from my "historical reality," and that (2) on my account, God always by nature wills the greatest good.
My response is that both (1) and (2) are ambiguous. In the senses in which they are true, they are irrelevant; in the senses in which they relevant, they are false.
In (1), the phrase 'my created essence' can refer either to what I am, i.e. the sort of entity I am, a human being, or to who I am, i.e. what distinguishes me in particular both from other human beings and from myself at any given stage of change. Now in terms of what I am, my created essence is obviously distinct from my historical reality. One's being an instance of humanity does not, by itself, tell us anything about me in particular; it only tells us what sort of entity I am, which in turn tells us nothing about my concrete historical reality. But nothing in my argument requires otherwise, nor does the truth in question affect my argument. Now if we take the phrase 'my created essence' to mean who I am, there's also a sense in which who I am is distinct from my concrete historical reality: I remain who I am despite all sorts of changes, such as age, virtue, experience, weight, amount of hair, etc. But that doesn't affect the argument either. What Elliot is really suggesting is that I can be who I am without having come to be as I have, i.e. by sexual intercourse between my parents at a particular time and place, in virtue of which there came to be a human being with this set of genes and dispositions as opposed to other, equally conceivable ones. If that suggestion were correct, then the sort of argument I've made above could not succeed. For God would be under no constraint to create me through the physical means by which I have come to be; and if so, then I could not maintain that "in the sort of world where innocents would be spared [disproportionate] suffering, the innocents of this particular world could not have existed at all."
Another distinction is needed here. It is indeed not absolutely necessary for God to create by secondary causes. God could have created without secondary causes—though it's hard to understand how, as opposed to stipulating that, a collection of entities which do not help cause each other to be would constitute a world. But given that God creates a world in which secondary causes are the ordinary means by which the particular constituents of that world come to be, it is hypothetically necessary that who I am depend in part on how I came to be. For what I am includes being a body of a certain sort, such that after the first instances of bodies of that sort, it is a causally necessary condition of being a body of that sort that one be constituted partly by inheritance from other bodies of that sort. God could of course have decreed that embodied, rational creatures come to be by some other means, or even without secondary causes at all; but such creatures would not be of just the same sort as we. Given how God has designed the universe, who I am includes, without being limited to, having come to be in a certain sort of way, which includes having had the parents I have, of whom the same is true in their turn. And so, while there are senses in which my created essence is distinct from my historical reality, that is not so in a sense that undermines my argument.
Elliot's (2) ignores a similar distinction between absolute and hypothetical necessity. According to Aquinas, given the kind of world God has created, there is a sense in which God "by nature wills the greatest good." Thus, given the kinds of entities the world contains, i.e. the constituents of the world, the composition of the world, i.e. its overall structure (whatever that is), must be optimal: the best possible for that set of constituents. But it does not follow that God must create, or even has created, the best possible set of constitutents. Such a notion is indeed arguably incoherent. For any creature is finite; and for whatever finite creature you pick, there's always some respect in which it could be better. God could always have created a more perfect kind of thing, similar in kind to the thing there is; and for whatever actual, individual thing you pick, there's always a respect in which it could be better relative to its kind.
Given as much, the hypothetical necessity by which God wills the best possible outcome for this world actually strengthens my argument. One could of course reply, as some have, that the sort of world in which innocents suffer disproportionately was not worth creating. But as I've said, we lack the standpoint from which we could know that. To say that is nothing but God's reply to Job.