David Lewis’s arguments against magical ersatzism are notoriously puzzling. Untangling different strands in those arguments is useful for bringing out what he thought was wrong with not just one style of theory about possible worlds, but with much of the contemporary metaphysics of abstract objects. After setting out what I take Lewis’s arguments to be and how best to resist them, I consider the application of those arguments to general theories of properties and relations. The constraints Lewis motivates turn out (...) to yield an argument for concretism about possible individuals that is quite different from the better-known Lewisian arguments for that position. The discussion also touches on the puzzling question of whether things are the way they are because of the properties they have, or are the properties and relations the way they are because of the things that have them. (shrink)

In this paper, I defend modal dimensionalism against the objection that it is ontologically and ideologically heavy. First, I briefly outline the theory and the objection against it. The objection relies on the widely accepted view that ontological and ideological parsimony are operational criteria when comparing metaphysical theories. Second, I outline the conventional distinction between ontology and ideology in the metaphysical tradition. Third, I challenge a particular kind of parsimony: reduction by identification. Fourth, even if reduction by identification is accepted, (...) I show that theories that pursue this often minimize differences, and that such minimization paves the way to epistemic underdetermination. Finally, I demonstrate that some theories in modal metaphysics also suffer from difference minimization and should thus not be measured on the ontology/ideology scale. (shrink)

David Lewis objected to theories that posit necessary connections between distinct entities and to theories that involve a magical grasping of their primitives. In On the Plurality of Worlds, Lewis objected to nondescript ersatzism on these grounds. The literature contains several reconstructions of Lewis’ critique of nondescript ersatzism but none of these interpretations adequately address his main argument because they fail to see that Lewis’ critique is based on broader methodological considerations. I argue that a closer look at his methodology (...) reveals the broader objection he presented against nondescript ersatzism. This objection, I further argue, remains a challenge for the ersatzer who posits structure-less entities as possible worlds. (shrink)

If the property _being a methane molecule_ is a universal, then it is a structural universal: objects instantiate _being a methane molecule_ just in case they have the right sorts of proper parts arranged in the right sort of way. Lewis argued that there can be no satisfactory account of structural universals; in this paper I provide a satisfactory account.