I maintain that there are modes of being. To be precise, I maintain that it is intelligible that there be modes of being. This puts me at odds with those, like van Inwagen, who consider the idea unintelligible and rooted in an elementary mistake:
. . . the thick conception of being is founded on the mistake of transferring what properly belongs to the nature of a chair -- or of a human being or of a universal or of God -- to the being of the chair. (Ontology, Identity, and Modality, Cambridge 2001, p. 4)
To clarify the issue let's consider God and creatures. God exists. Socrates exists. God and Socrates differ in their natures. For example, Socrates is ignorant of many things, and he knows it; God is ignorant of nothing. God is unlimited in power; Socrates is not. And so on. So far van Inwagen will agree. But I take a further step: God and Socrates differ in the way they exist: they differ in their mode of being. So I make a three-fold distinction among the being (existence) of x, the nature (quiddity, whatness) of x, and the mode of being of x. At most, van Inwagen makes a two-fold distinction between the being of x and the nature of x. For me, God and Socrates differ quidditatively and existentially whereas for van Inwagen they differ only quidditatively (in respect of their natures).
One difference between God and Socrates is that God does not depend on anything for his existence while Socrates and indeed everything other than God depends on God for his/its existence, and indeed, at every time at which he/it exists. I claim that that this is a difference in mode of existence: God exists-independently while creatures exist-dependently. There would be an adequate rebuttal of my claim if thin translations could be provided of the two independent clauses of the initial sentence of this paragraph. By a thin translation of a sentence I mean a sentence that is logically equivalent to the target sentence but does not contain 'exist(s) or cognates or 'is' used existentially. Translations are easy to provide, but I will question whether they are adequate. Let 'D' be a predicate constant standing for the dyadic predicate ' --- depends for its existence on ___.' And let 'g' be an individual constant denoting God.
1. God does not depend on anything for his existence
2. Everything other than God depends on God for its existence
2-t. (x)[(~(x = g) --> Dxg].
I will now argue that these thin translations are not adequate.
I begin with the obvious point that the domain of the bound variable 'x' is a domain of existent objects, not of Meinongian nonexistent objects. It is also obvious that the thin translations presuppose that each of these existents exists in the same sense of 'exists' and that no one of them differs from any other of them in respect of mode of existence. Call this the three-fold presupposition.
Now consider the second translation, (2-t) above. It rests on the three-fold presupposition, and it states that each of these existents, except God, stands in the relation D to God. But this is incoherent since there cannot be a plurality of existents -- 'existent' applying univocally to all of them -- if each existent except God depends on God for its existence. It ought to be obvious that if Socrates depends on God for his very existence at every moment, then he cannot exist in the same way that God exists.
I don't deny that there is a sense of 'exists' that applies univocally to God and Socrates. This is the sense captured by the particular quantifier. Something is (identically) God, and something else is (identically) Socrates. 'Is identical to something' applies univocally to God and Socrates. My point, however, is that the x to which God is identical exists in a different way than the y to which Socrates is identical. That 'is identical to something' applies univocally to both God and Socrates is obviously consistent with God and Socrates existing in different ways.
Here is another way to see the point. To translate the target sentences into QuineSpeak one has to treat the presumably sui generis relation of existential dependence of creatures on God as if it were an ordinary external relation. But such ordinary relations presuppose for their obtaining the existence of their relata. But surely, if Socrates is dependent on God for his very existence, then his existence cannot be a presupposition of his standing in the sui generis relation to God of existential dependence. He cannot already (logically speaking) exist if his very existence derives from God.
The point could be put as follows. The Quinean logic presupposes ontological pluralism which consists of the following theses: everything exists; there is a plurality of existents; each existent exists in the same sense of 'exists.' Ontological pluralism, however, is incompatible with classical theism according to which each thing distinct from God derives its existence from God. On classical theism, everything other than God exists-derivatively and only God exists-underivatively.
On the Quinean scheme of ontological pluralism, the only way to connect existents is via relations that presuppose the existence of their relata. So the relation of existential dependence that is part and parcel of the notion of divine creation must be misconstrued by the Quinean ontological pluralist as a relation that presupposes the logically antecedent existence of both God and creatures.
The ontology presupposed by Quine's logic is incompatible with the theism van Inwagen espouses. One cannot make sense of classical theism without a doctrine of modes of being. One cannot be a classical theist and a thin theorist.