Published online by Cambridge University Press: 28 July 2016
The classical conception of God is that of a necessary being. On a possible worlds semantics, this entails that God exists at every possible world. According to the modal realist account of David Lewis, possible worlds are understood to be real, concrete worlds – no different in kind from the actual world. But, modal realism is equipped to accommodate the existence of a necessary being in only one of three ways: (1) By way of counterpart theory, or (2) by way of a special case of trans-world identity for causally inert necessary beings (e.g. pure sets), or else (3) causally potent ones which lack accidental intrinsic properties. I argue that each of these three options entails unacceptable consequences – (1) and (2) are incompatible with theism, and (3) is incompatible with modal realism. I conclude that (at least) one of these views is false.