... Inwagen offers a rather different argument than Leibniz. He argues for why there is anything at all while Leibniz argues for the existence of a necessary being which therefore explains the existence of the kind of world which we now inhabit. Inwagen’s argument has four premises;
1. There are some beings. 2. If there is more than one possible world there are infinitely many. 3. There is at most one possible world where there are no beings. 4. For any two possible worlds, the probability of them being actual is equal.
Inwagen argues that there are an infinite number of ways the world might actually be. By the principle of sufficient reason all of these ways should be equally likely, there is no reason that one should be chosen over another. He states that there is no way to distinguish between the worlds either internally or externally in order to assign different probabilities to them. Inwagen then says there cannot be more than one world which is empty and contains no beings. He asks us to imagine that the world is created by an infinite number of switches and that for an empty world they must all be set to the ‘off’ position. This would be one possibility out of infinitely many. Inwagen is using the principle of identity of indiscernibles here which states that indistinguishable possibilities are one and the same possibility. It follows that if the probability of there being nothing is zero then the probability of there being something is therefore one.
I think that Inwagen’s argument is stronger than the one put forward by Leibniz. Inwagen does not rely on a necessary being and I find the argument generally stronger and less open to criticism. ...
