Plurality of Worlds

by David Kellogg Lewis

Book Overview

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.

• Format: Paperback
• Language: English
• ISBN: 0631224262
• ISBN13: 9780631224266
• Release Date: February 2001
• Publisher: Wiley-Blackwell
• Length: 288 Pages
• Weight: 1.18 lbs.
• Dimensions: 0.8" x 6.8" x 9.8"

Customer Reviews

The Case for Modal Realism.

In the book _On the Plurality of Worlds_, analytic philosopher David Lewis presents his case for modal realism (also called "extreme modal realism", though why it is "extreme" is questioned). As Lewis explains, "This book defends modal realism: the thesis that the world we are part of is but one of a plurality of worlds, and that we who inhabit this world are only a few out of all the inhabitants of all the worlds." Lewis will argue for this position based on the fact of the utility of modal realism for philosophy provides reason to believe that it is true (just as the utility of set theory provides reason to believe that there are sets), then he will consider the common objections to this position and argue against them. Lewis maintains that he does not provide an argument that effectively requires one to believe in a plurality of worlds, but only that he will provide a cost-benefits analysis of this idea. The idea of possible worlds is a recurrent one in the philosophy of Leibniz; however, Lewis does not mention him because he feels that any interpretation he might offer of Leibniz's works would be inadequate. David Lewis (1941-2001) who taught at Princeton was one of the more interesting thinkers in analytic philosophy and this book is certain to remain a classic and can be appreciated even if one cannot go all the way with Lewis in accepting his arguments for modal realism. It should also be pointed out that Lewis' arguments while often subtle can be followed with some effort and that he presents a very effective case. This book consists of four chapters. The first chapter "A Philosophers' Paradise" lays the case for modal realism and argues that a plurality of worlds has utility in philosophy. Lewis begins by noting that he will restrict himself to possibilia and by writing off impossibilia. Lewis then goes on to explain how the usefulness of a plurality of worlds makes it likely for one to think that it is indeed true. Lewis considers the case of a possible worlds analysis of modality (showing how the "diamond" ("possibly") and "box" ("necessarily") symbols are mutually interdefinable and can be understood in terms of possible worlds). Lewis also considers the idea of "closeness" of possible worlds and defines such notions as counterfactuals and verisimilitude. Following this, Lewis considers content of possible worlds and considers analyses of thought, belief, and language. Lewis then shows how modal realism may be used to explain properties (universals and tropes), the fact that possible worlds are isolated and not spatio-temporally connected, and the fact of concreteness, plenitude, and actuality. Lewis maintains that actuality must be understood by making use of an indexical analysis. The second chapter "Paradox in Paradise?" shows some of the commonly made objections to modal realism and argues for why Lewis thinks they are inadequate. Lewis considers the objections made that according to his analysis "everything is a

Most significant contribution to metaphysics in many years

It's obvious to me that some of these reviewers don't understand either what Lewis was doing in this book or the standard philosophical response to it. He wasn't arguing that there are multiple universes connected to ours in some way explorable through science. Those would be parts of this world, in Lewis' sense. The worlds he's talking about are possible worlds. They aren't actual. That is, they don't exist in any way spatiotemporally or causally connected with the actual world. And yet he says they're as concrete as we are.Philosophers' responses to this view are incredibly interesting. They think the idea is nuts, and yet they have no way to resist the conclusion that he gives compelling arguments that his view solves numerous philosophical problems that no one has been able to deal with in a perfectly satisfactory way. This doesn't convince many people that his view is correct, but the response has been pretty strong among those who want to use his system without thinking that it's true. They call it a modal fiction, and the view is called fictionalism. This is becoming incredibly influential among metaphysicians.Aside from all that, most metaphysicians today recognize this book as just incredibly fruitful and creative in bringing together so many different strains in metaphysics. He deals with so many problems in such a lucid way that the book serves to introduce many problems in metaphysics, making advances in the discussion even apart from the contribution of his main thesis.

A philosopher's paradise--in inspired lunacy

Lewis' work always produces mixed feelings in me. There is a long list of good things to be said on his behalf, and, so far as I can see, only one really bad thing. But the bad thing is bad enough to taint my otherwise unalloyed (and profound) respect and admiration for this superb thinker, quite probably the best philosopher alive, and almost certainly the best I've ever read. (Aaron, if you are reading this, you were right about your teacher; he deserves all the plaudits you kept showering on him, and for all I know he may even be right about the crazy things he says.)First, the pros. Lewis offers a modal metaphysics that is a) technically brilliant, elegant, and well-motivated, b) capable of providing reductive analyses of a vast range of otherwise obscure notions, and c) the best game in town if considered simply on it theoretical merits. He shows how his modal realism can be used to analyze modality (necessity, possibility, and the like, as well as restricted modalities) and mental and semantic content, and to make room for properties and counterfactual claims. He shows how to dissolve the debate among essentialists and anti-essentialists using counterpart theory, how to avoid various apparently serious objections to modal realism, and how to understand the debates about de re modality and "transworld identity". He offers a clear account of ersatzism, especially of the linguistic variety, which (I agree with him in holding) is the only real alternative to his modal realism among the theories so far offered, and is as such clearly an inferior theory. He offers a devastating argument against "magical ersatzism", probably the most commonly held view on modality apart from linguistic approaches. The argument is decisive, I think, and shows that approaches like those of Plantinga or Stalnaker cannot succeed. His modal realism has its limitations; because he cannot help himself to worlds bigger than a certain size and shape, and because he has all the worlds as concrete objects existing "side by side", so to speak, he can't countenance the full range of possibilities that an ersatzist can, and his analyses come apart at the edges. (For instance, the thesis of the plurality of worlds itself is, on Lewis' account, necessarily false; thus he must believe in necessarily false truths. Again, he cannot admit the possibility of two spatiotemporally disconnected universes, or worlds that differ as to which non-spatiotemporal abstracta exist in them.) When these defects are compared against the defects of Lewis' competitors, however, his view emerges as the clear winner.Nonetheless, in the end all of this theoretical advantage is not enough. The thesis of the plurality of worlds is simply incredible. Indeed, I would go so far as to say that its falsehood is something like a Moorean fact; it disagrees so badly with common sense that no philosophical considerations in its favor could constitute an adequate reason for accepting it. Lewis's meth

OK, I changed my mind

This is awesome stuff, which everyone needs to know. So what if it's false? There are tons of ultra cool ideas in here, and as far as taking the ball and running with it, there's nothing better this century. -- Benj Hellie

A brilliant defense of an unorthodox view of modal logic.

Lewis argues that the semantics of modal logic are best served by postulating the existence of a set of possible worlds, so that our modal operators refer to states of affairs within those worlds. He argues by analogy with numbers that the causal independence of those worlds is no obstacle to their theoretical usefulness, and offers detailed criticism of several attempts to simulate modal semantics without postulating the worlds as really existing. His positive argument for his own view primarily involves looking at other issues in modal logic from the perspective of his modal realism, showing how his view can help shed light on those issues. His discussion of those issues is of great independent interest even to those skeptical of his modal realism.