On the Plurality of Worlds
Lewis (David)
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BOOK ABSTRACT:

Cover Blurb

  1. 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.
  2. Lewis argues that the philosophical utility of modal realism is a good reason for believing that it is true. After putting forward the type of modal realism he favors, Lewis answers numerous objections that have been raised against it. These include an insistence that everything must be actual; paradoxes akin to those that confront naive set theory; arguments that modal realism leads to inductive skepticism, or to disregard for prudence and morality; and finally, sheer incredulity at a theory that disagrees so badly with common opinion. Lewis grants the weight of the last objection, but takes it to be outweighed by the benefits to systematic theory that acceptance of modal realism brings. He asks whether these same benefits might be gained more cheaply if we replace his many worlds by many merely ′abstract′ representations; but concludes that all versions of this ′ersatz modal realism′ are in serious trouble. In the final chapter, Lewis distinguishes various questions about trans–world identity, and argues that his ′method of counterparts′ is preferable to alternative approaches.
  3. David Lewis (1941 – 2001) was Professor of Philosophy at Princeton University. His publications include Convention (reissued by Blackwell 2002), "Lewis (David) - Counterfactuals" (reissued by Blackwell 2000), "Lewis (David) - Parts of Classes" (1991), and of numerous articles in metaphysics and other areas. Many of his writings are available in his Collected Papers.

Amazon Customer Review
  1. If you're at all interested in analytic philosophy, it's surely worth being acquainted with David Lewis, and this is probably the essential Lewis book. His defence of modal realism is beautifully written, with clear, lucid arguments, and it covers a wide range of philosophical problems in an accessible manner. Possible worlds are postulated within modal logic, but there's no difficult formal logic here; anyone with an interest in the book and a bit of background in philosophy should be able to follow the main ideas easily.
  2. I do think there are big problems here... in fact, I find analytic metaphysics in general to be quite seriously misguided, and much of OPW isn't particularly relevant to my worldview or approach to philosophy. Yet I still love it. Lewis was one of the great system-builders, and despite how much I strongly disagree with most of his system, I find it ingenious and fascinating. Not only because I like craziness, and one of the core ideas is pretty crazy (though maybe not so crazy these days - I'm aware, though I haven't read any books on it yet, that some people (e.g. Yagisawa1) now espouse 'extended modal realism', which would add impossible worlds to our ontology), but also because Lewis was just a superb writer with a superb mind.
  3. Unsurprisingly, the vast majority of philosophers reject modal realism due to its deeply counter-intuitive ontology. However, over time it's shown itself to be a powerful theory. The nature of possible worlds is a lively debate in metaphysics, and OPW remains one of the most important books on the subject.
  4. If you want another example of modal realism in action and you're interested in the God debate, check out Lewis's short essay "Lewis (David) - Anselm and Actuality", in which he uses a modal realist framework to provide a brilliant refutation of Anselm's famous ontological argument. It was available online last time I checked, or if not, in "Lewis (David) - Philosophical Papers Volume I" (which is probably as good a place as any to go if you want more Lewis after OPW).
  5. Incidentally, modal realism has nothing to do with any theories of the multiverse postulated in physics. It's a mistake2 to conflate the two.



In-Page Footnotes ("Lewis (David) - On the Plurality of Worlds")

Footnote 1: Presumably the relevant paper is "Yagisawa (Takashi) - Beyond Possible Worlds". I have my doubts that Yagisawa is really positing the existence of impossible worlds, but rather setting up a reductio concerning Lewis’s arguments for possible worlds.

Footnote 2: I agree – there seems to be just such a mistake in "Salmon (Nathan) - An Empire of Thin Air: Review of David Lewis's "On the Plurality of Worlds"".


BOOK COMMENT:

On-Line at Web Link.



"Lewis (David) - On the Plurality of Worlds (Selections)"

Source: Haslanger (Sally) & Kurtz (Roxanne) - Persistence : Contemporary Readings


Full Text
  1. Our question of overlap of worlds parallels the this-worldly problem of identity through time; and our problem of accidental intrinsics parallels1 a problem of temporary intrinsics, which is the traditional problem of change. Let us say that something persists iff, somehow or other, it exists at various times; this is the neutral word. Something perdures if it persists by having different temporal parts, or stages, at different times, though no one part of it is wholly present at more than one time; whereas it endures if it persists by being wholly present at more than one time. Perdurance corresponds to the way a road persists through space; part of it is here and part of it is there, and no part is wholly present at two different places. Endurance corresponds to the way a universal2, if there are such things, would be wholly present wherever and whenever it is instantiated. Endurance involves overlap: the content of two different times has the enduring thing as a common part. Perdurance does not3.
  2. (There might be mixed cases: entities that persist by having an enduring part and a perduring part. An example might be a person who consisted of an enduring entelechy ruling a perduring body; or an electron that had a universal of unit negative charge as a permanent part, but did not consist entirely of universals. But here I ignore the mixed cases. And when I speak of ordinary things as perduring, I shall ignore their enduring universals, if such there be.)
  3. Discussions of endurance versus perdurance tend to be endarkened by people who say such things as this: "Of course you are wholly present at every moment of your life, except in case of amputation. For at every moment all your parts are there: your legs, your lips, your liver...." These endarkeners may think themselves partisans of endurance, but they are not. They are perforce neutral, because they lack the conceptual resources to understand what is at issue. Their speech betrays — and they may acknowledge it willingly — that they have no concept of a temporal part. (Or at any rate none that applies to a person, say, as opposed to a process or a stretch of time.) Therefore they are on neither side of a dispute about whether or not persisting things are divisible into temporal parts. They understand neither the affirmation nor the denial. They are like4 the people — fictional, I hope — who say that the whole of the long road is in their little village, for not one single lane of it is missing. Meaning less than others do by 'part', since they omit parts cut crosswise, they also mean less than others do by 'whole'. They say the 'whole' road is in the village; by which they mean that every 'part' is; but by that, they only mean that every part cut lengthwise is. Divide the road into its least lengthwise parts; they cannot even raise the question whether those are in the village wholly or only partly. For that is a question about crosswise parts, and the concept of a crosswise part is what they lack. Perhaps 'crosswise part' really does sound to them like a blatant contradiction. Or perhaps it seems to them that they understand it, but the village philosophers have persuaded them that really they couldn't, so their impression to the contrary must be an illusion. At any rate, I have the concept of a temporal part; and for some while I shall be addressing only those of you who share it.
  4. Endurance through time is analogous to the alleged trans-world identity of common parts of overlapping worlds; perdurance through time is analogous to the "trans-world identity," if we may call it that, of a trans-world individual composed of distinct parts in non-overlapping worlds. Perdurance, which I favour for the temporal case, is closer to the counterpart theory which I favour for the modal case; the difference is that counterpart theory concentrates on the parts and ignores the trans-world individual composed of them.
  5. The principal and decisive objection against endurance, as an account of the persistence of ordinary things such as people or puddles, is the problem of temporary intrinsics. Persisting things change their intrinsic properties. For instance shape: when I sit, I have a bent shape; when I stand, I have a straightened shape. Both shapes are temporary intrinsic properties; I have them only some of the time. How is such change possible? I know of only three solutions.
  6. (It is not a solution just to say how very commonplace and indubitable it that we have different shapes at different times. To say that is only to insist — rightly — that it must be possible somehow. Still less is it a solution to say it in jargon — as it might be, that bent-on-Monday and straight-on-Tuesday are compatible because they are 'time-indexed properties' — if that just means that, somehow, you can be bent on Monday and straight on Tuesday.)
  7. First Solution: Contrary to what we might think, shapes are not genuine intrinsic properties. They are disguised relations, which an enduring thing may bear to times. One and the same enduring thing may bear the bent-shape relation to some times, and the straight-shape relation to others. In itself, considered apart from its relations to other things, it has no shape at all. And likewise for all other seeming temporary intrinsics; all of them must be reinterpreted as relations that something with an absolutely unchanging intrinsic nature bears to different times. The solution to the problem of temporary intrinsics is that there aren't any temporary intrinsics. This is simply incredible, if we are speaking of the persistence of ordinary things. (It might do for the endurance of entelechies or universals.) If we know what shape is, we know that it is a property, not a relation.
  8. Second Solution: The only intrinsic properties of a thing are those it has at the present moment. Other times are like false stories; they are abstract representations, composed out of the materials of the present, which represent or misrepresent the way things are. When something has different intrinsic properties according to one of these ersatz other times, that does not mean that it, or any part of it, or anything else, just has them — no more so than when a man is crooked according to the Times, or honest according to the News. This is a solution that rejects endurance; because it rejects persistence altogether. And it is even less credible than the first solution. In saying that there are no other times, as opposed to false representations thereof, it goes against what we all believe. No man, unless it be at the moment of his execution, believes that he has no future; still less does anyone believe that he has no past.
  9. Third Solution: The different shapes, and the different temporary intrinsics generally, belong to different things. Endurance is to be rejected in favour of perdurance. We perdure; we are made up of temporal parts, and our temporary intrinsics are properties of these parts, wherein they differ one from another. There is no problem at all about how different things can differ in their intrinsic properties.


COMMENT:




In-Page Footnotes ("Lewis (David) - On the Plurality of Worlds (Selections)")

Footnote 1: Lewis says that he’s indebted to "Armstrong (David) - Identity Through Time" in this regard, “and to Johnston”, whose terminology he follows. The only reference to a “Johnston” in the bibliography of "Lewis (David) - On the Plurality of Worlds" is to the PhD dissertation “Particulars and Persistence” by Mark Johnston – presumably Mark Johnston.

Footnote 2: I take issue with this in a footnote to "Hawley (Katherine) - David Lewis on Persistence".

Footnote 3: It does, I think, but in different ways. Part of the perdurantist explanation of Fission (Click here for Note) involves shared stages, so two spacetime worms overlap for a period of their existence.

Footnote 4: I don’t think this analogy is helpful, or even very clear. The “darkeners” seem to have a concept of spatial parts (the bodily organs) but not temporal parts. The analogy seems to be of those who have a concept of lengthways parts (the lanes) but not of crossways parts (sections of road, most of which are outside the small village). It all seems rather forced.



"Lewis (David) - On the Plurality of Worlds: Preface"

Source: Lewis - On the Plurality of Worlds, 1986, Preface


Full Text
  1. 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.
  2. I begin the first chapter ("Lewis (David) - A Philosopher's Paradise") by reviewing the many ways in which systematic philosophy goes more easily if we may presuppose modal realism in our analyses. I take this to be a good reason to think that modal realism is true, just as the utility of set theory in mathematics is a good reason to believe that there are sets. Then I state some tenets of the kind of modal realism I favour.
  3. In the second chapter ("Lewis (David) - Paradox or Paradise?"), I reply to numerous objections. First I consider arguments that modal realism leads to contradiction; and I reply by rejecting some premises that are needed to produce the paradoxes. Then I turn to arguments that modal realism leads to consistent but unwelcome views: inductive scepticism, a disregard for prudence and morality, or a loss of the brute arbitrariness of our world; and again I reply by finding premises to reject. Finally I consider the sheer implausibility of a theory so much at variance with commonsensical ideas about what there is; I take this to be a fair and serious objection, but outweighed by the systematic benefits that acceptance of modal realism brings.
  4. In the third chapter ("Lewis (David) - Paradise on the Cheap?"), I consider the prospect that a more credible ontology might yield the same benefits: the programme of ersatz modal realism, in which other worlds are to be replaced by 'abstract' representations thereof. I advance objections against several versions of this programme. I urge that we must distinguish the different versions, since they are subject to different objections; it will not do to dodge trouble by favouring abstract ersatz worlds in the abstract, without giving any definite account of them.
  5. In the fourth and final chapter ("Lewis (David) - Counterparts or Double Lives"), I consider the so-called 'problem of trans-world identity'. I divide it into several questions, some of them good and some of them confused, and I compare my counterpart-theoretic approach with some alternatives.
  6. Nowhere in this book will you find an argument that you must accept the position I favour because there is no alternative. I believe that philosophers who offer such arguments are almost never successful, and philosophers who demand them are misguided. I give some reasons that favour my position over some of its close alternatives. But I do not think that these reasons are conclusive; I may well have overlooked some close alternatives; and I do not discuss more distant alternatives at all. For instance, I do not make any case against a hard-line actualism that rejects any sort of quantification over possibilities. You will find it easy enough to guess why I would not favour that view; I have nothing new, and nothing conclusive, to say against it; so it would serve no purpose to discuss it.
  7. It may come as a surprise that this book on possible worlds also contains no discussion of the views of Leibniz. Is it that I consider him unworthy of serious attention? - Not at all. But when I read what serious historians of philosophy have to say, I am persuaded that it is no easy matter to know what his views were. It would be nice to have the right sort of talent and training to join in the work of exegesis, but it is very clear to me that I do not. Anything I might say about Leibniz would be amateurish, undeserving of others' attention, and better left unsaid.
  8. About twelve years ago, I gave my thesis a bad name. I called it 'modal realism'. Had I foreseen present-day discussions of what 'realism' really is, I would certainly have called it something else. As it is, I think it best to stick with the old name. But I must insist that my modal realism is simply the thesis that there are other worlds, and individuals inhabiting these worlds; and that these are of a certain nature, and suited to play certain theoretical roles. It is an existential claim, not unlike the claim I would be making if I said that there were Loch Ness monsters, or Red moles in the CIA, or counterexamples to Fermat's conjecture, or seraphim. It is not a thesis about our semantic competence, or about the nature of truth, or about bivalence, or about the limits of our knowledge. For me, the question is of the existence of objects - not the objectivity of a subject matter.
  9. At many points, I am greatly indebted to friends who have helped me by discussion or correspondence about topics covered in this book: especially Robert M. Adams, D. M. Armstrong, John G. Bennett, John Bigelow, Phillip Bricker, M. J. Cresswell, Peter Forrest, Allen Hazen, Mark Johnston, David Kaplan, Saul Kripke, Robert Stalnaker, Pavel Tichy and Peter van Inwagen.
  10. Part of this book was delivered as the John Locke Lectures at the University of Oxford in Trinity Term, 1984. I am most honoured by Oxford's invitation; and I am most grateful to Oxford for providing me with the occasion to write on modal realism more fully than I had done before, and also with a much-needed deadline. I am grateful to Princeton University for sabbatical leave, and to the National Endowment for the Humanities for financial assistance, during the year in which most of the book was written.



"Lewis (David) - The Problem of Temporary Intrinsics"

Source: Van Inwagen & Zimmerman - Metaphysics: The Big Questions


Full Text
  1. Let us say that something persists iff, somehow or other, it exists at various times; this is the neutral word1. Something perdures iff it persists by having different temporal parts, or stages, at different times, though no one part of it is wholly present at more than one time; whereas it endures iff it persists by being wholly present at more than one time. Perdurance corresponds to the way a road persists through space; part of it is here and part of it is there, and no part is wholly present at two different places. Endurance corresponds to the way a universal, if there are such things, would be wholly present wherever and whenever it is instantiated. Endurance involves overlap: the content of two different times has the enduring thing as a common part. Perdurance does not.
  2. (There might be mixed cases: entities that persist by having an enduring part and a perduring part. An example might be a person who consisted of an enduring entelechy ruling a perduring body; or an electron that had a universal of unit negative charge as a permanent part, but did not consist entirely of universals. But here I ignore the mixed cases. And when I speak of ordinary things as perduring, I shall ignore their enduring universals, if such there be.)
  3. Discussions of endurance versus perdurance tend to be endarkened by people who say such things as this: 'Of course you are wholly present at every moment of your life, except in case of amputation. For at every moment all your parts are there: your legs, your lips, your liver. . . .' These endarkeners may think themselves partisans of endurance, but they are not. They are perforce neutral because they lack the conceptual resources to understand what is at issue. Their speech betrays - and they may acknowledge it willingly - that they have no concept of a temporal part. (Or at any rate none that applies to a person, say, as opposed to a process or a stretch of time.) Therefore they are on neither side of a dispute about whether or not persisting things are divisible into temporal parts. They understand neither the affirmation nor the denial. They are like the people - fictional, I hope - who say that the whole of the long road is in their little village, for not one single lane of it is missing. Meaning less than others do by 'part', since they omit parts cut crosswise, they also mean less than others do by 'whole'. They say the 'whole' road is in the village; by which they mean that every 'part' is; but by that, they only mean that every part cut lengthwise is. Divide the road into its least lengthwise parts; they cannot even raise the question whether those are in the village wholly or only partly. For that is a question about crosswise parts, and the concept of a crosswise part is what they lack. Perhaps 'crosswise part' really does sound to them like a blatant contradiction. Or perhaps it seems to them that they understand it, but the village philosophers have persuaded them that really they couldn't, so their impression to the contrary must be an illusion. At any rate, I have the concept of a temporal part; and for some while I shall be addressing only those of you who share it2.
  4. . . . The principal and decisive objection against endurance, as an account of the persistence of ordinary things such as people or puddles, is the problem of temporary intrinsics. Persisting things change their intrinsic properties. For instance shape: when I sit, I have a bent shape; when I stand, I have a straightened shape. Both shapes are temporary intrinsic properties; I have them only some of the time. How is such change possible? I know of only three solutions.
  5. (It is not a solution just to say how very commonplace and indubitable it is that we have different shapes at different times. To say that is only to insist - rightly - that it must be possible somehow. Still less is it a solution to say it in jargon - as it might be, that bent-on-Monday and straight-on-Tuesday are compatible because they are 'time-indexed properties' - if that just means that, somehow, you can be bent on Monday and straight on Tuesday.)
  6. First solution: contrary to what we might think, shapes are not genuine intrinsic properties. They are disguised relations, which an enduring thing may bear to times. One and the same enduring thing may bear the bent-shape relation to some times, and the straight-shape relation to others. In itself, considered apart from its relations to other things, it has no shape at all. And likewise for all other seeming temporary intrinsics; all of them must be reinterpreted as relations that something with an absolutely unchanging intrinsic nature bears to different times. The solution to the problem of temporary intrinsics is that there aren't any temporary intrinsics. This is simply incredible, if we are speaking of the persistence of ordinary things. (It might do for the endurance of entelechies or universals.) If we know what shape is, we know that it is a property, not a relation.
  7. Second solution: the only intrinsic properties of a thing are those it has at the present moment. Other times are like false stories; they are abstract representations, composed out of the materials of the present, which represent or misrepresent the way things are. When something has different intrinsic properties according to one of these ersatz other times, that does not mean that it, or any part of it, or anything else, just has them - no more so than when a man is crooked according to the Times, or honest according to the News. This is a solution that rejects endurance; because it rejects persistence altogether. And it is even less credible than the first solution. In saying that there are no other times, as opposed to false representations thereof, it goes against what we all believe. No man, unless it be at the moment of his execution, believes that he has no future; still less does anyone believe that he has no past.
  8. Third solution: the different shapes, and the different temporary intrinsics generally, belong to different things. Endurance is to be rejected in favour of perdurance. We perdure; we are made up of temporal parts, and our temporary intrinsics are properties of these parts, wherein they differ one from another. There is no problem at all about how different things can differ in their intrinsic properties.


COMMENT: From "Lewis (David) - On the Plurality of Worlds".




In-Page Footnotes ("Lewis (David) - The Problem of Temporary Intrinsics")

Footnote 1: My discussion of this problem is much indebted to "Armstrong (David) - Identity Through Time" (1980); and to Mark Johnston. I follow Johnston in terminology.

Footnote 2:



"Salmon (Nathan) - An Empire of Thin Air: Review of David Lewis's "On the Plurality of Worlds""

Source: Salmon (Nathan) - Metaphysics, Mathematics, and Meaning, 2005


Oxford Scholarship Online
    The modal theory that David Lewis defended in On the Plurality of Worlds (Blackwell, 1986) is criticized. According to Lewis, to say that John Kerry might have won the 2004 presidential election is to say that someone very similar to Kerry does win his presidential election in a parallel universe (in an alternative “possible world”). This theory is indicative of a serious misunderstanding of such modal expressions as ‘possibly’ and ‘necessarily’, which are concerned not with any goings on in parallel universes but with what might have been. One need not disbelieve in possible worlds to recognize that they are not parallel universes.


COMMENT: Review of "Lewis (David) - On the Plurality of Worlds"; Philosophical Review, Vol. 97, No. 2, Apr., 1988, pp. 237-244



"Lewis (David) - A Philosopher's Paradise"

Source: Lewis - On the Plurality of Worlds, 1986, Chapter 1


Contents
  1. The Thesis of Plurality of Worlds – 1
  2. Modal Realism at Work: Modality – 5
  3. Modal Realism at Work: Closeness – 20
  4. Modal Realism at Work: Content – 27
  5. Modal Realism at Work: Properties – 50
  6. Isolation – 69
  7. Concreteness – 81
  8. Plenitude – 86
  9. Actuality – 92


COMMENT: See "Funkhouser (Eric) - Notes on Lewis, “A Philosopher's Paradise”" for Notes.



"Lewis (David) - Paradox or Paradise?"

Source: Lewis - On the Plurality of Worlds, 1986, Chapter 2


Contents
  1. Everything is Actual? – 97
  2. All Worlds in One? – 101
  3. More Worlds Than There Are? – 104
  4. How Can We Know? – 108
  5. A Road to Scepticism? – 115
  6. A Road to Indifference? – 123
  7. Arbitrariness Lost? – 128
  8. The Incredulous Stare – 133



"Lewis (David) - Paradise on the Cheap?"

Source: Lewis - On the Plurality of Worlds, 1986, Chapter 3


Contents
  1. The Ersatzist Programme – 136
  2. Linguistic Ersatzism – 142
  3. Pictorial Ersatzism – 165
  4. Magical Ersatzism – 174



"Lewis (David) - Counterparts or Double Lives"

Source: Lewis - On the Plurality of Worlds, 1986, Chapter 4


Contents
  1. Good Questions and Bad – 192
  2. Against Overlap – 198
  3. Against Trans-World Individuals – 210
  4. Against Haecceitism – 220
  5. Against Constancy – 248



"Lewis (David) - Counterparts or Double Lives (Selections)"

Source: Lewis - On the Plurality of Worlds, 1986, Chapter 4


Comment
  1. The Selections are the whole1 of:-
    • 1. Good Questions and Bad, and
    • 5. Against Constancy
  2. There is also a useful footnote on the distinction between Genuine Modal Realism and Ersatz Modal Realism, presumably indebted to Chapter 3 ("Lewis (David) - Paradise on the Cheap?").


COMMENT:




In-Page Footnotes ("Lewis (David) - Counterparts or Double Lives (Selections)")

Footnote 1: So, the intervening sections:-
  • 2. Against Overlap
  • 3. Against Trans-World Individuals, and
  • 4. Against Haecceitism
are omitted.


Text Colour Conventions (see disclaimer)
  1. Blue: Text by me; © Theo Todman, 2017
  2. Mauve: Text by correspondent(s) or other author(s); © the author(s)



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