In a blog post entitled, An Argument from Wayne and Garth, Daniel Vecchio from Vexing Questions offers a symmetry breaker for the possibility premise in the modal ontological argument. The argument is as follows:
P1: If a maximally great being is impossible, then it is possible that I am worthy of worship
P2: It is not possible that I am worthy of worship
C1: A maximally great being is not impossible
C2: A maximally great being is possible
P3: If a maximally great being is possible, there is a maximally great being
C3: There is a maximally great being
In defense of the premises, Vecchio offers the following in support of the argument:
Beginning with the first premise, Vecchio maintains that ‘if there are no possible worlds where there is a being that has a maximal set of compossible great-making properties, then there is at least some possible world where he, or his counter-part, is the greatest being that happens to exist, and so he would be of greatest worth, i.e. worthy of worship’.
Unfortunately, the antecedent of the conditional in his defense is nonsensical. If it’s a maximal set of compossible great-making properties, they’re definitionally compossible, i.e., possibly jointly instantiated. So of course there is some possible world where such a being exists—that’s definitionally true. Also, it is not at all clear that we should suppose the greatest being that happens to exist entails that such a being is worthy of worship. It doesn’t follow that there’s a possible world where you, or your counterpart, is the greatest being. Perhaps you’re essentially mediocre, such that in any world in which you exist, there’s another being that’s better. Furthermore, an electron is not worthy of worship, even if it exists alone and is therefore the greatest thing in its world. So, in addition to having a ludicrous antecedent, the conditional as a whole is a clear non-sequitur.