There is an interesting conversation going on about creatio ex nihilo in the 'philosophosphere', so I thought I'd jump in. Anyone who reads this weblog regularly can almost certainly guess what my position is, so I won't belabor it. What I do want to discuss, briefly, is a contribution by Flood, responding to Vallicella. Two arguments in particular stand out:
A) Now that which is not distinct from a thing logically cannot fail to be that thing. Therefore the creation that issues from God’s operation upon himself is, necessarily, God. If God exists, then for any x, x is either God or a creature of God: tertium non datur. For God to create, but not out of that which is other than God, is for God to create out of God. Perhaps Vallicella can shown, or has already shown in PTE, how the product of such a process could be other than God. Absent such a showing, the logic of exnihilation would seem to issue in pantheism.
B) When we use “dependent” to express the relationship of one thing (or attribute, state, or trait) to another, we abstract that relationship from all the others the two may have to each other. The predicate “dependent” cannot express the totality of relationships that the one has to the other. That is because non-dependency or independence in at least one respect is a necessary condition of non-identity or difference. If a is dependent on b in one respect, then there must be at least one other respect whereby it is not the case that a is dependent on b. The notion of total dependence, dependence in every respect, entails identity, and therefore no dependence at all. If a is dependent on b in all respects, then a “collapses” into b, taking dependency, and difference, with it.
If a is dependent on b in all respects, then any difference between a and b is merely nominal, i.e., “a” and “b” are two names for the identical entity.
I don't see any reason to agree with the aspects of these two arguments that I have bolded above. (A) seems to require that all causation be operation on something pre-existent. There's a certain imaginative plausibility, given that this is the way causation generally works in our experience; but I can't think of any reason why one would need this to be an essential part of causation. Likewise, with regard to (B), the claim about total dependence seems to be simply false; for in a case of total dependence one of the things about b that would be dependent on a would be the distinction between a and b - and I see no reason why such a distinction could not be part of b's dependence on a. (It's worth pointing out, too, that the 'total dependence' here could very well just be total dependence of all positive attributes; and this would not, as far as I could see cause any problem even if we assumed Flood's principle here.)
It's always possible that I'm missing something key in the movement here; but the moves seem to be far too quick. And when one looks more closely at them, it's difficult to find any good reason for those moves, or, at least, I find it difficult.
Since Aquinas is ultimately in the background here, it's worth pointing out that he responds to something like the move in (A) in the response to Objection 2 here; and I think the response to Objection 2 in another place would be at least related to the issue in (B) - although I find (B) immensely more obscure than (A). Flood also introduces problem of evil issues; Aquinas responds to these sorts of issues here. It's also worth pointing out (since it's also an issue in the discussion) that, while Aquinas's full understanding of creation ex nihilo requires appeal to his doctrine of the composition of essentia and esse, essence and actual being, it doesn't (again, as far as I can see) play any obvious role in his ST discussion of creatio ex nihilo itself. This is so even when he argues that only God can create; the issue in his discussion is always the nature of the cause, not the constitution of the effect. He does integrate his doctrine of creation with the composition doctrine in De Potentia; what he says there seems to me to be entirely reasonable, but then, I think the composition doctrine in its basic form is entirely reasonable - we can't simply conflate actual being and kind of being as if they were the same thing; indeed, I'm not sure what that would mean. As Aquinas sometimes puts it, existence is other than essence. Aquinas's doctrine goes a bit beyond this basic point, but I find it a hard question to determine how much farther it goes. [As far as I can tell from my readings so far, I don't think it goes much farther; and the bit it adds seems reasonable to me.] The idea is found in De ente et essentia:
Everything that receives something from another is in potency with respect to what it receives, and that which is received in the thing is its act; therefore, a quiddity or form that is an intelligence is in potency with respect to the existence that it receives from God, and this received existence is received as its act.
For Aquinas 'compositio' typically means a union in which one element of the union is identifiable as act and the other is identifiable as potency; so the question of whether we can make sense of his view that creatures are composed of essentia and esse really boils down to whether we can regard essence as really potential to actual being in the created substance itself. It doesn't, I think, have anything to do with 'reception' [in a fairly literal sense] (as the original criticism in Deck's exegesis seemed to be); Aquinas talks about reception because it's a natural word to use when talking about the act-potency relation, not because it's carrying any serious metaphysical burden in the actual composition doctrine. In other words, we can afford to take the 'reception' talk very loosely; and so the question would just be: Is there some reasonable sense in which we can say essence receives existence [i.e., is there a sense in which e could say essence is really potential to existence]? I don't see why there wouldn't be. I have to look more closely at Deck's criticisms; I didn't find them convincing at all, but Aquinas and I tend to be congruent souls on most things, so he usually makes more sense to me on first blush than his critics do. As I said, I'll have to look more closely at the criticisms.
UPDATE: Clark had already put up an interesting post at Mormon Metaphysics; see also his comment below for clarification as to how it relates to my post here. I should also give the URL of the post by Vallicella to which Flood is responding; that is here. I've also added a few small things in brackets above for clarification.