It follows from Humean principles of plenitude, I argue, that island universes are possible: physical reality might have 'absolutely isolated' parts. This makes trouble for Lewis's modal realism; but the realist has a way out. First, accept absolute actuality, which is defensible, I argue, on independent grounds. Second, revise the standard analysis of modality: modal operators are 'plural', not 'individual', quantifiers over possible worlds. This solves the problem of island universes and confers three additional benefits: an 'unqualified' principle of compossibility (...) can be accepted; the possibility of nothing can be accommodated; and the identity of indiscernible worlds can be decisively refuted. (shrink)

Assuming that we find the concept of naturalness coherent, we shall no doubt wish to allow that certain relations count as highly natural. Many of us will think that various spatio-temporal and causal relations—is the cause of, is spatially separated from, is later than—are highly natural. Some of us will think that various basic semantic and mentalistic relations—refers to, attends to, believes.…--- are highly natural. Some will think that various logico-mathematical relations—being the successor of, being identical to…—are highly natural.

In this paper I argue that Modal Realism, the thesis that there exist non-actual possible individuals and worlds, can be made compatible with Metaphysical Nihilism, the thesis that it is possible that nothing concrete exists. Modal Realism as developed by Lewis rules out the possibility of a world where nothing concrete exists and so conflicts with Metaphysical Nihilism. In the paper I argue that Modal Realism can be modified so as to be compatible with Metaphysical Nihilism. Such a modification makes (...) Modal Realism neither incur further theoretical costs nor lose its theoretical benefits. Thus such a modification constitutes an improvement of Modal Realism. (shrink)