Here’s an attempt at formulating a modal-cosmological argument for the existence of God (I take it it is cosmological precisely because it deals with contingency, and arguments from contingency typically get classified under cosmological arguments). The argument could go like this:
- There is no logically possible world in which nothing [meaning ‘not-anything’] exists.
- If there is no logically possible world in which nothing exists, then there is some necessary being [‘necessary being’ being defined as a being which exists in all logically possible worlds].
- A necessary being exists (from 1&2 conditional elimination)
- If there is a necessary being then it is a being the idea of which involves existence.
- There is only one being the idea of which involves existence, and this is a maximally great being (a being to which belong all the great making properties maximally or infinitely). [alternatively: if there is any being the idea of which involves existence then there is a maximally great being].
- But there is a necessary being (from 3), and therefore there is a being the idea of which involves existence (from 3&4 conditional elimination).
- There is a maximally great being (from 5&6 conditional elimination)
I think this argument is sound, and the premises are intuitively obviated. The first premise is not very controversial among modal logicians, as it asks whether it is even possible for nothing to exist – and most philosophers think it is evident that if anything at all exists, then the only possible explanation for its existence is that ‘something’ must exist. Premise 2 is self-evident. Premise 3 follows from 1&2. Premise 4 is an attempt to cut through the objection that there may be multiple necessary beings (beings which exist in all logically possible worlds) thus undermining the legitimacy of leading from necessary being to a maximally great being in the traditional sense. If premises 4 and 5 weren’t logically true, then we would have to appeal to something like Occam’s Razor in order to argue that we should be conservative in our assumptions and admit only one necessary being. However, premise 4 is simply fleshing out the conceptual or modal nature of ‘necessary being’ as involving existence. Premise 5 claims that there is no such being other than a maximally great being (in other words, that there is no idea any philosopher has ever had of something the essence of which involved existence, and yet which was not a/the maximally great being). One might object to premise 5 by claiming that there may be some necessary being which does not have all the great making properties, and thus cannot appropriately be called ‘God’. However, I would respond in two ways: first, I’m not sure that it is even coherent to suggest that some necessary being fail to have all the great making properties maximally – but suppose I were to be dialectically charitable and grant, for the sake of argument, the concession that such a necessary being could exist: I would ask the objector to provide any example of such a being. If they appeal to numbers or to propositions which they think are necessary beings, then they would be appealing to a form of platonism with which I wouldn’t be terribly impressed (on the upside, at least they’d have had to leave Naturalism behind in an attempt to avoid the existence of God consistently). I would argue that neither numbers nor propositions exist as beings on their own which are necessary and not in any way contingent on God. From 5 to 7 the deductive chain seems solid.
Alternatively we could construct the argument like this:
- If a maximally great being does not exist then there is no necessary being.
- If there is no necessary being then there is a logically possible world in which nothing exists.
- But there is not a logically possible world in which nothing exists.
- Therefore there is a necessary being (from 2&3 conditional elimination)
- Therefore a maximally great being exists (from 4&1)