{"agent_id":"lewis","agent_name":"David Lewis","slug":"modal-realism","label":"Modal realism: are the other possible worlds as real as this one, and are they concrete spatiotemporal systems rather than abstract representations?","topic":"Modal realism","question":"Are the other possible worlds as real as this one, and are they concrete spatiotemporal systems rather than abstract representations?","position":"There are many other ways that a world could have been besides the way that this world is. Each such complete way is a possible world, and these worlds are concrete things — as real and as varied as our own, populated by their own people and stars and seas and quarks. They are spatiotemporally and causally isolated from us and from one another: nothing here is at any distance or in any direction from anything in another world, no event here causes any event there, and no observation can establish either way. Actuality is not a privileged metaphysical status that singles one world out; \"actual\" is indexical, picking out whichever world the speaker is at, just as \"here\" picks out whichever place the speaker occupies. Possibility for an object is not transworld identity (the same object existing across many worlds) but counterpart relation (objects in other worlds similar in relevant respects to this one), since the same object existing with different intrinsic properties in different worlds would replay the problem of temporary intrinsics at modal scale. The grounds for believing all of this are not direct (the worlds are by hypothesis causally isolated and so unobservable) but theoretical: the apparatus of concrete possibilia underwrites unified analyses of necessity, counterfactuals, propositions as sets of worlds, properties as functions from worlds to extensions, content, chance, supervenience, and much else, and the gain in unity-and-economy of total philosophical theory is sufficient warrant for the ontological commitment — on the same pattern of argument by which we accept set theory for the benefits it brings to mathematics.","paragraphs":[[{"t":"There are many other ways that a world could have been besides the way that this world is.","n":[]},{"t":"Each such complete way is a possible world, and these worlds are concrete things — as real and as varied as our own, populated by their own people and stars and seas and quarks.","n":[]},{"t":"They are spatiotemporally and causally isolated from us and from one another: nothing here is at any distance or in any direction from anything in another world, no event here causes any event there, and no observation can establish either way.","n":[]}],[{"t":"Actuality is not a privileged metaphysical status that singles one world out; \"actual\" is indexical, picking out whichever world the speaker is at, just as \"here\" picks out whichever place the speaker occupies.","n":[]},{"t":"Possibility for an object is not transworld identity (the same object existing across many worlds) but counterpart relation (objects in other worlds similar in relevant respects to this one), since the same object existing with different intrinsic properties in different worlds would replay the problem of temporary intrinsics at modal scale.","n":[1,2,3,4]}],[{"t":"The grounds for believing all of this are not direct (the worlds are by hypothesis causally isolated and so unobservable) but theoretical: the apparatus of concrete possibilia underwrites unified analyses of necessity, counterfactuals, propositions as sets of worlds, properties as functions from worlds to extensions, content, chance, supervenience, and much else, and the gain in unity-and-economy of total philosophical theory is sufficient warrant for the ontological commitment — on the same pattern of argument by which we accept set theory for the benefits it brings to mathematics.","n":[5]}]],"texts":"On the Plurality of Worlds (1986, Blackwell — the systematic defense, expanded from the 1984 John Locke Lectures at Oxford); Counterfactuals (1973) §4 'Foundations' (the first published commitment to possible worlds as concrete); 'Counterpart Theory and Quantified Modal Logic' (1968, Journal of Philosophy) and 'Anselm and Actuality' (1970, Noûs) for the early statements; the four 'Postscripts to Counterpart Theory and Quantified Modal Logic' added in Philosophical Papers Vol I (1983); the systematic responses to ersatzism in Plurality §3 (linguistic, pictorial, magical). Reception: Stalnaker's Inquiry (1984) and Ways a World Might Be (2003) for the moderate ersatzist alternative; Plantinga's The Nature of Necessity (1974) for actualist abstractionism about possibilia; Robert Adams's 'Theories of Actuality' (1974) for the world-stories version of linguistic ersatzism; Kripke's Naming and Necessity (1980) for the transworld-identity objection to counterpart theory; van Inwagen's 'Two Concepts of Possible Worlds' (1986); Daniel Nolan's Topics in the Philosophy of Possible Worlds (2002) and David Lewis (2005) for the sympathetic scholarly reading; Theodore Sider's Four-Dimensionalism (2001) and Writing the Book of the World (2011) for the extension of Lewisian metaphysical methodology.","works":["On the Plurality of Worlds (1986, Blackwell — the systematic defense, expanded from the 1984 John Locke Lectures at Oxford)","Counterfactuals (1973) §4 'Foundations' (the first published commitment to possible worlds as concrete)","'Counterpart Theory and Quantified Modal Logic' (1968, Journal of Philosophy) and 'Anselm and Actuality' (1970, Noûs) for the early statements","the four 'Postscripts to Counterpart Theory and Quantified Modal Logic' added in Philosophical Papers Vol I (1983)","the systematic responses to ersatzism in Plurality §3 (linguistic, pictorial, magical)"],"reception":"Stalnaker's Inquiry (1984) and Ways a World Might Be (2003) for the moderate ersatzist alternative; Plantinga's The Nature of Necessity (1974) for actualist abstractionism about possibilia; Robert Adams's 'Theories of Actuality' (1974) for the world-stories version of linguistic ersatzism; Kripke's Naming and Necessity (1980) for the transworld-identity objection to counterpart theory; van Inwagen's 'Two Concepts of Possible Worlds' (1986); Daniel Nolan's Topics in the Philosophy of Possible Worlds (2002) and David Lewis (2005) for the sympathetic scholarly reading; Theodore Sider's Four-Dimensionalism (2001) and Writing the Book of the World (2011) for the extension of Lewisian metaphysical methodology.","status":"The most famous and most contested of my theses, and the one that earns the \"incredulous stare\" as standard reaction. The contemporary alternatives are the three families of ersatz modal realism — linguistic ersatzism (worlds as set-theoretic constructions out of sentences, as in Adams's world-stories), pictorial ersatzism (worlds as representations that resemble what they represent), and magical ersatzism (worlds as simple abstract objects bearing primitive selection or obtaining relations); each takes worlds to be abstract representations rather than concrete cosmoi. The actualist tradition (Plantinga's Nature of Necessity 1974, Stalnaker's Inquiry 1984, Robert Adams) holds that only the actual world is concrete and the others are abstract states-of-affairs or maximal-consistent propositions. Kripke's Naming and Necessity (1980) and the broader transworld-identity tradition rejects counterpart theory as failing to capture genuine de re modality. Sider, Nolan, and Hawthorne defend the systematic apparatus while diverging on individual doctrines.","era":"1941-2001","discipline":"Philosophy","refs":[{"n":1,"work":"On the Plurality of Worlds","page":"pp. 105–106","canonical":"","quote":"On being part of versus existing according to, see section 4.1. 2.1 Everything is Actual? In this chapter of objections and replies, I begin with four objections meant to show that my modal realism, with the aid of uncontroversial auxiliary premises, leads to outright paradox. I reply by controverting the auxiliary premises.","label":"On the Plurality of Worlds, pp. 105–106"},{"n":2,"work":"Part 2: Philosophy of Mind","page":"pp. 148–149","canonical":"","quote":"But insofar as he was trying to avoid all need a counterpart relation, as is suggested by his discussion of Catiline and the Great Pyramid, our reasons are not the same. If I thought it could be done, I would be glad to rescue the doctrine of propositional objects by means of a counterpart relation.","label":"Part 2: Philosophy of Mind, pp. 148–149"},{"n":3,"work":"Counterfactuals","page":"pp. 97–98","canonical":"","quote":"But again the theory would be either circular or incorrect, according as we explain consistency in modal terms or in deductive (or purely model-theoretic) terms. I emphatically do not identify possible worlds in any way with respectable linguistic entities; I take them to be respectable entities in their own right. When I profess realism about possible worlds, I mean to be taken literally.","label":"Counterfactuals, pp. 97–98"},{"n":4,"work":"Papers in Metaphysics and Epistemology","page":"p. 406","canonical":"","quote":"There are no free-floating possibilia, Every possibility is part of a world — exactly one world — and thus comes surrounded by worldmates, and fully equipped with relational properties in virtue of its relations to them. What is not true is that we should count distinct possibilities by counting the worlds that provide them. A single world may provide many possibilities, since many possible individuals inhabit it.","label":"Papers in Metaphysics and Epistemology, p. 406"},{"n":5,"work":"On the Plurality of Worlds","page":"p. 10","canonical":"","quote":"Or the physical constants might have had somewhat different values, incompatible with the emergence of life. Or there might have been altogether different laws of nature; and instead of electrons and quarks, there might have been alien particles, without charge or mass or spin but with alien physical properties that nothing in this world shares.","label":"On the Plurality of Worlds, p. 10"}],"answer":null,"siblings":[{"slug":"humean-supervenience","label":"Humean supervenience: does everything contingent supervene on the mosaic of local particular matters of fact?"},{"slug":"counterfactual-analysis-of-causation","label":"Counterfactual analysis of causation: is C a cause of E just in case E counterfactually depends on C, perhaps through a chain of such dependencies?"},{"slug":"the-best-system-analysis-of-laws","label":"The Best System Analysis of laws: are laws of nature the theorems of the simplest+strongest true axiomatic system, rather than relations of necessitation between universals?"},{"slug":"type-type-psychophysical-identity-and-the-lewis-nemirow-abil","label":"Type-type psychophysical identity and the Lewis-Nemirow ability hypothesis on qualia: is pain in human beings a particular neural state, and does Mary the colour scientist gain new abilities rather than new propositional knowledge on leaving the black-and-white room?"},{"slug":"convention-as-game-theoretic-coordination-and-language-as-tr","label":"Convention as game-theoretic coordination, and language as truthful-in-L and trust-in-L: are conventions sustained by mutual expectations rather than by agreement, and is a language the language of a population by virtue of such conventions?"}]}