Theism and Modal Collapse

God is traditionally taken to be a necessarily existing being who is unsurpassably powerful, knowledgeable, and good. The familiar problem of actual evil claims that the presence of gratuitous suffering in the actual world constitutes evidence against the existence of such a being. In contrast, the problem of possible evil claims that the possibility of bad worlds constitutes evidence against theism. How? It seems plausible to suppose that there are very bad possible worlds. But if God exists in every world, then God exists in those, too. And if God exists in very bad worlds, some say, God is culpable for not ensuring that they are better. This paper considers this argument, surveys some responses, and offers a novel solution. Along the way, it argues that theists should maintain that the actual world is a multiverse featuring all and only universes worthy of being created and sustained by God, and – more controversially – it recommends that theists embrace modal collapse: the claim that this multiverse is the only possible world.