With the growing rivers of ink being spilt over the modal ontological argument, it seems that intelligent atheists and theists alike have recognized that, when framed as a modal argument, the premise “it is possible for God to exist” is semantically identical to “God exists”. Therefore, if an atheist were to respond to the modal ontological argument by saying that “there is a logically possible world in which I exist and a Maximally great being does not exist” the theist could respond by saying that the atheist is begging the question, since the theist does not admit that there is any logically possible world where a maximally great being does not exist. The current state of affairs has set the game such that, for anyone who thinks that it is logically possible that God exists, that person should recognize that God necessarily does exist. The concept of God involves necessary existence, and therefore if the concept of God exists (ie., is coherent) then it follows for any subject S to whom the idea is an intellectually live option, S must, on pain of irrationality, believe that God exists. The argument, therefore, has become over whether the concept of a maximally great or necessary being is itself coherent. This seems self-evident to me, and my intuition about this is rather strong, but it is always difficult to demonstrate it to somebody for whom a concept of a maximally great being isn’t intellectually live.
Therefore, what if one were to go about it using philosophy of language and modality to make this concept of a necessary being intellectually live? Let us consider the following sentence:
“It is possible for nothing to exist”
Obviously “nothing exists” is problematic, since what we mean by ‘nothing’ is not itself ‘some-thing’ but rather is just ‘not-anything’ – which means that ‘nothing’ is not here a noun. The sentence does not mean that some-thing we call ‘nothing’ exists, but rather is a negative statement: “not anything exists.” However, existence needs to be assumed for the grammar of the sentence. When one says of any ‘X’ that it does or does not exist one assumes at least that it is logically possible for ‘X’ to exist. However, if not anything exists is true, then its opposite is possibly affirmed. However, the opposite of ‘not anything exists’ just is ‘something exists’, and for something to exist requires that the concept of ‘existence’ be possibly applied to something. However, for the concept of existence to be coherent ‘something exists’ must be true (without at least ‘something’, to say that X exists is meaningless). Therefore, the sentence “nothing exists” seems to be incoherent.
Another way to go about making the same point is to argue that there is no logically possible world (given any account of ‘possible worlds’ you like) where nothing exists. Therefore, it is not logically possible for nothing to exist. It follows that it is logically necessary that something exist. It is a bit more controversial to get from ‘something exists’ to ‘something exists such that it cannot not exist’. However, with a little work we can bridge this gap too. Consider the argument of Maimonedes; if it is possible for anything which exists to cease to exist, and if the world (as the sum of all things which exist) is contingent upon these particulars, then given an infinite amount of time eventually the possibility that all things fall out of existence simultaneously will be realized. His argument was intended to demonstrate that the universe either was not eternal in the past, or else at least that if it was, then it is not comprised exclusively of contingent parts. I think the logic he presents is flawed because it is possible that, given an infinite amount of time, some logically possible possibilities are never actualized. To demonstrate this all one has to do is to say that there are infinite sets which are infinite whether or not they contain particular members which they could contain. Thus, a monkey at a typewriter, if given an infinite amount of time, will not necessarily write Romeo & Juliet since the set of all things it could compose over time would be infinite even if it never wrote Romeo & Juliet. However, his argument does do one useful thing for our purposes. Imagine that the world is comprised of things which exist such that they may or may not exist – that implies that it is logically possible for all things to cease to exist. However, it is not logically possible for not-anything to exist. Therefore the world cannot be comprised exclusively of things which exist such that they may or may not exist. It follows, then, that there is at least one thing which exists such that it cannot not exist. Therefore the concept of a necessary being is logically necessary. If somebody is to suggest that perhaps there is no one thing which must exist, but that there are some things which are related as (~B>A)&(~A>B), but for my purposes I would count that as a single thing and argue that it was incontingent.
It seems to me that with this kind of argument one can manage to spin off a successful ontological argument and a successful cosmological argument at the same time – the two proofs which have claimed precisely to prove beyond any logically possible doubt that God exists.