- There is a logically possible world in which there is at least one contingent being.
- If there is a logically possible world in which there is at least one contingent being, then there is an incontingent being.
- There is an incontingent being.
- If there is an incontingent being, then there is a necessary being.
- There is a necessary being.
- If there is a necessary being, then it is a maximally great being.
- There is a maximally great being.
This argument is only really effective at all on the person who believes that though nothing in the actual world is contingent, it is possible for a thing to be contingent. However, the person arguing that nothing is actually contingent has not gone far enough – they must argue that it is not logically possible that a contingent thing exist, which requires that they demonstrate some syntactical-modal absurdity. Lines 4-7 are just there to elaborate incontingency, but if one wanted to pick those out as problematic then they have probably missed where this argument might be interesting. I could just as well have stopped at 3 and then said, as Aquinas at one point does in the Summa, that all people know this is what is meant by ‘God’. I can then argue piecemeal for the other features of what an incontingent being would look like.
In other words, if it is even logically possible for a thing to be contingent, then God exists (presuming that no contingent being could possibly exist without a sufficient reason of it’s existence). I say it is trivial because generally those who deny that the cosmological argument from contingency is compelling think that nothing is or could be contingent. However, those who are die-hard set against contingency should give us a demonstration of it’s syntactical-modal absurdity (and it might be important to say that they should be careful to ensure that the proof is not logically-possibly wrong, on pain of a further problem obviated by possible world semantics; namely that there would still be a logically possible world in which a contingent being exists). Moreover, those who aren’t sure as of yet should take inventory of the consequence of even admitting the possibility of contingency.
For simplicity, let’s also suggest here that contingency can be construed in the following way: a being is contingent just in case it is logically possible that it not exist, and it does not contain the sufficient reason of its existence within itself.