Consider the following argument for the existence of God.
1. Something exists.
2. Anything that exists must either exist contingently or necessarily.
3. It is impossible that everything that exists is contingent.
4. Therefore, there must exist at least one necessary being.
5. Only God could be a necessary being.
6. Therefore, God exists.
I think any argument in support of 5 is going to be very weak, but I propose to set it aside for this post and focus on 2 (only peripherally on 3).
In order for 2 to be defensible, it first has to be the case that necessity and contingency are coherently applicable to the existence of things. Prima facie, it certainly seems so:
(C) x exists contingently if and only if x exists and it is possible that x might not have existed.
(N) x exists necessarily if and only if x exists and x does not exist contingently (x exists and it is not possible that x might not have existed).
It is hard to deny that there are all sorts of things that exist that didn’t have to exist, so it follows from (C) that they exist contingently. But if contingent existence is coherent, then (since necessary existence is defined in terms of it) necessary existence also seems to be coherent.
I find myself highly sympathetic to Quine’s claim that “Necessity resides in the way we talk about things, not in the things we talk about.” (Ways of Paradox and Other Essays (1976), p. 174.) If a view along these lines is correct, then perhaps the whole idea of a necessary being or a thing that exists necessarily is a conceptual muddle. It might be like saying that the order of things on my dining room table is grammatically correct, or that I had nouns for breakfast, or that my furnace is true. A defense of the necessity of God’s existence would have to consist not in talking about necessity as an attribute or descriptor of God, himself, but rather in talking about the necessity of the statement “God exists,” — on how “God” is conceived or defined. But this “analytic necessity,” when applied to God, leads to a notoriously disappointing end. Whether anything exists or not isn’t a function of its concept or definition (so said Kant, and I tend to agree). We can define or conceive God as existing, but for God to actually have the property of existing, God would, of course, first have to exist. Saying that something exists won’t make it exist. Nor will saying that something necessarily exists. In order for something to have any property at all, it first has to exist. If it does exist, that makes it pointless to then go on and ask whether or not it also turns out to have the property of existing. It is true of anything at all that, necessarily, if it exists then it exists; given any existing thing, look closely and you will discover that it has the property of existing and couldn’t exist without it.
There are cases where a Quinean view seems just wrong. If I say that it is necessary that the sides of a square meet at right angles, this seems to a statement about the square; not the way I talk about the square. The sides will meet at a right angle whether anyone talks about the square or not. That is, having sides that meet in a right angle seems to be something that is a necessary property of the square, itself, and not merely a property of the way we talk about squares. But this sort of “constitutional necessity” (as we might call it) also requires that the thing in question first exists. To say that God exists as a matter of constitutional necessity also turns out to require that God first exists. It also turns out to be true of anything else — necessarily, if something exists, it will be part of its constitution that it exists.
All this seems to imply something interesting: that existence is always contingent. Since existence can’t be legitimately built into the definition or concept of anything, whatever exists can be conceived without contradiction not to exist, and therefore (C) applies to every existing thing, and (N) doesn’t apply to anything.
To put this in possible world talk, consider the following conversation snippet:
Theist: “I think God exists in every possible world.”
Nontheist: “No, because I can imagine a possible world in which nothing exists but this pineapple.”
It looks like if you can’t define something into existence in one world, you certainly can’t define it into existence in all worlds. The theist, then, is simply wrong to think that God can be usefully defined or conceived as existing in all possible worlds (saying God exists in all possible worlds doesn’t and can’t make it true).
Consider how this applies to a modal argument for God’s existence such as this one defended by Joe Hinman (http://metacrock.blogspot.com/2017/06/special-discussion-for-hunter.html):
1a. God is either necessary or impossible.
2a. God can be conceived without contradiction.
3a. Whatever can be conceived without contradiction is not impossible.
4a. God is not impossible.
5a. God’s existence is a necessity
6a. If God is necessary, then God exists.
7a. Belief in God’s existence is warranted
(I’ve added the letter ‘a’ after each premise number to contrast with the argument below). Note that (7a) is logically superfluous, but let’s let that pass. Instead, compare that argument with this one:
1b. God is either necessary or impossible.
2b. God’s nonexistence can be conceived without contradiction.
3b. Whatever can be conceived without contradiction is not impossible.
4b. God’s nonexistence is not impossible. (From 2b and 3b)
5b. God’s existence is not necessary.
6b. God is impossible. (From 1b and 5b)
7b. Whatever is impossible does not exist.
8b. God does not exist. (From 6b and 7b)
The only way to salvage Joe’s modal argument is to revert to the position that existence can be built into the concept of something so that (2b) is ruled out. But if, as I have been suggesting, anything can be conceived as not existing — if analytically necessary existence is a muddle — then this argument is in trouble. And I think it is. The argument fails at 1a/1b.
There is another kind of necessity worth considering. This would be the idea of being “necessary for”. This is what is involved in causal arguments (God is necessary for everything to have a cause), in arguments from explanatory regress, or in arguments that God is necessary for reality to have ontological grounding (it is roughly this sort of necessity that Hinman appeals to in arguing that God is “Being-itself”). The idea here is that you can’t have B unless you have A. But the problem arises when you ask whether there is anything, in turn, that you need to have in order to have A. There are only three possibilities:
(1) The chain of dependence is infinitely regressive; for everything that exists, there is something else that is necessary for it.
(2) The chain of dependence terminates in something that is a brute fact (nothing explains it, nothing caused it, and it doesn’t depend on anything else — it just is).
(3) The chain of dependence terminates in something that exists necessarily — not in the sense of being “necessary for,” but in being necessary in itself.
But it looks very much like we have ruled (3) out, and (1) doesn’t seem a promising way to get to God. This leaves (2). I have said before that I think theists should be more open to the idea that God is not a necessary being. If the whole notion of necessary existence is a confusion, then theism should either be rejected or rehabilitated to reject the view that God is either necessary or nothin’. Theism just needs a logically weaker concept of God. If theists give up as lost the game of trying to prove that God has to exist as a matter of logic or conceptual necessity, it seems to me they can still try to argue that God at least happens to exist. The obvious disadvantage to this is that theists will have to give up pretensions to being on clearly superior grounds in holding God to be the foundational brute fact rather than something impersonal.