I think one of the deepest questions philosophy can ask is why nature exhibits the order and regularity it does, and one of the most fundamental divisions among philosophers is between those who think it capable of explanation and those who do not. In western philosophy, one of the most common explanations proposed in answer to this question has been that our world is the product of some kind of design or creative intention, usually on the part of some spiritual beings, such as the gods or God. In this post I want to (somewhat briefly) explore the theistic version of this answer.
If there is indeed a God Who is roughly that of traditional theism—that is, an omniscient, omnipotent, omnibenevolent (etc.) being—it would seem that we have, on the face of it, a good explanation for the existence of an ordered, law-governed, and relatively life-friendly universe such as we find ourselves in. As an omnibenevolent being, God would plausibly have the desire to create other, in some respects similar beings with whom God could share God’s love. And as an omniscient and omnipotent being, God would certainly have the knowledge of how to create them and the power to do so. But we must be careful here. For what sort of explanation could one offer for God’s infinitely many creative decisions? As Hume pointed out long ago in his Dialogues Concerning Natural Religion, it would seem no good to explain the order and regularity of the created world by appealing to a mirror image of that world in the Divine Mind, when this image is itself without explanation. Perhaps the answer is that God’s nature dictates that every world which God could create has some minimal amount of order. (I think Duns Scotus believed something like this, but unfortunately I have not yet found a reference.) If so, we would have an explanation for the fact that the universe is ordered without having an explanation for the particular order it has.
We can flesh out the above solution to this problem in terms of the notion of a conditional decree, my term for something which is nicely spelled out by Alexander Pruss in his post “Creation, Aseity, and Providence” over at the Prosblogion. Basically, conditional decrees are of the form “If p then q, and if not-p then r”, where God both permits p to be true and permits not-p to be true, leaving the outcome to chance. If this is so, God could accommodate libertarian free will by willing conditionals of the form “If Scott freely chooses A then x will follow, and if Scott freely chooses B then y will follow, and if Scott freely chooses C then z will follow…” In this way God can plan “for all possible contingencies”, as Pruss puts it, so that even though certain matters are left to chance—such as Scott’s choice between A, B, and C—something which God wants will occur in any case.
If this account of God’s creative plan is correct, we might suppose that God makes the same decrees, both conditional and unconditional, in all possible worlds where God exists. Thus God could decree unconditionally that some contingent things exist, that some of them are to be conscious and intelligent (etc.), while leaving their exact nature unspecified. God could then use conditional decrees to cover all the matters that are left unsettled by God’s unconditional decrees. On this supposition we do not have to explain how it comes about that God wills one thing when God might have willed something different, while at the same time holding that the existence of God is compatible with a wide variety of different possible worlds. We also wouldn’t have to worry about God’s decrees depending on God’s foreknowledge of what will actually happen. Thus God’s will—that is, the totality of God’s decrees—supervenes on God’s nature, for God’s nature does not vary from world to world. God’s will constrains reality without determining it in every detail, though nothing occurs without God’s permission. Thomas Aquinas once said that it does not follow from the fact that certain things change that God’s will changes, only that God wills that things should change (Summa Theologiae (A.k.a. Summa Theologica), Prima Pars, Question 19, Article 7). In much the same spirit, we can say that from the fact that certain things happen differently in different possible worlds, it does not follow that God’s will differs in different possible worlds, only that God wills that certain things should happen differently in different ones.