This book is a defense of modal realism; the thesis that our world is but one of a plurality of worlds, and that the individuals that inhabit our world are only a few out of all the inhabitants of all the worlds. Lewis argues that the philosophical utility of modal realism is a good reason for believing that it is true.

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)

By what process of development he came to this opinion, though in itself an important and interesting question, is logically irrelevant to the inquiry how far the opinion itself is correct ; and among his opinions, when these have been ascertained, it becomes desirable to prune away such as seem inconsistent with his main doctrines, before those doctrines themselves are subjected to a critical scrutiny. Philosophic truth and falsehood, in short, rather than historical fact, are what primarily demand our attention (...) in this inquiry. (shrink)

We are accustomed to thinking of space and time as particulars or individuals—even if we should hesitate to describe them as things or objects or substances. We say ‘space has three dimensions’, ‘material things occupy space’, ‘the debris has disappeared into space’ and we talk in a comparable fashion about time. Not only do we think of space and time as individuals but, in many connections at any rate, we think of them as unique individuals. When we talk about spaces (...) and times in the plural, when we say ‘fill up the spaces on the form’, ‘it could go in the space between the lamp and the door’, ‘there were peaceful times in the early years of their marriage’ we think of these multiple spaces and times as parts of the unique allencompassing space and the unique all-encompassing time. Kant believed that we could not help thinking of them in this way. We do, at any rate, in fact think like this and it is this conviction that I want to examine. (shrink)

Here, Bob Hale and Crispin Wright assemble the key writings that lead to their distinctive neo-Fregean approach to the philosophy of mathematics. In addition to fourteen previously published papers, the volume features a new paper on the Julius Caesar problem; a substantial new introduction mapping out the program and the contributions made to it by the various papers; a section explaining which issues most require further attention; and bibliographies of references and further useful sources. It will be recognized as the (...) most powerful presentation yet of a neo-Fregean program. (shrink)

_Possible Worlds_ presents the first up-to-date and comprehensive examination of one of the most important topics in metaphysics. John Divers considers the prevalent philosophical positions, including realism, antirealism and the work of important writers on possible worlds such as David Lewis, evaluating them in detail.

In this paper we examine Lewis's attempts to provide an epistemology of modality and we argue that he fails to provide an account that properly weds his metaphysics with an epistemology that explains the knowledge of modality that both he and his critics grant. We argue that neither the appeals to acceptable paraphrases of ordinary modal discourse nor parallels with Platonistic theories of mathematics suffice. We conclude that no proper epistemology for modal realism has been provided and that one is (...) needed. (shrink)