It's possible the ontological argument is the dumbest argument of all time.
If it's possible that it's the dumbest argument of all time, then it's the dumbest argument of all time in some possible world
If it's the dumbest argument in some worlds, then it's the dumbest argument in all Worlds
If it's the dumbest argument in all worlds, then it's the dumbest argument in the real world
If it's the dumbest argument in the real world, then it being the dumbest argument is true
Therefore, it's the dumbest argument
If it's possible that it's the dumbest argument of all time, then it's the dumbest argument of all time in some possible world
If it's the dumbest argument in some worlds, then it's the dumbest argument in all Worlds
If it's the dumbest argument in all worlds, then it's the dumbest argument in the real world
If it's the dumbest argument in the real world, then it being the dumbest argument is true
Therefore, it's the dumbest argument