•  14
    The Forrest-Armstrong argument, as reconfigured by David Lewis, is a reductio against an unrestricted principle of recombination. There is a gap in the argument which Lewis thought could be bridged by an appeal to recombination. After presenting the argument, I show that no plausible principle of recombination can bridge the gap. But other plausible principles of plenitude can bridge the gap, both principles of plenitude for world contents and principles of plenitude for world structures. I conc…Read more
  •  5
    A Sketch of Reality
    In Modal Matters: Essays in Metaphysics, Oxford University Press. pp. 3-39. 2020.
    In this introductory chapter to my collection of papers, Modal Matters, I present my tripartite account of reality. First, I endorse a plenitudinous Platonism: for every consistent mathematical theory, there is in reality a mathematical system in which the theory is true. Second, for any way of distributing fundamental qualitative properties over mathematical structures, there is a portion of reality that has that structure with fundamental properties distributed in that way; some of these porti…Read more
  •  176
    Journal of Philosophy 77 (7): 381-401. 1980.
    The article explicates a notion of prudence according to which an agent acts prudently if he acts so as to satisfy not only his present preferences, but his past and future preferences as well. A simplified decision-theoretic framework is developed within which three analyses of prudence are presented and compared. That analysis is defended which can best handle cases in which an agent's present act will affect his future preferences.
  •  34
    The Concept of Time (review)
    Philosophical Review 106 (4): 629. 1997.
  •  41
    Modal Matters: Essays in Metaphysics (edited book)
    Oxford University Press. 2020.
    This volume contains eighteen papers, three with new postscripts, that were written over the past 35 years. Five of the papers have not been previously published. Together they provide a comprehensive account of modal reality—the realm of possible worlds—from a Humean perspective, with excursions into neighboring topics in metaphysics. Part 1 sketches an account of reality as a whole, both the mathematical and the modal, defending a form of plenitudinous realism: every consistent proposition is …Read more
  •  36
    Ontological Commitment
    Stanford Encyclopedia of Philosophy. 2014.
  •  79
    Moderate composition as identity holds that there is a generalized identity relation, “being the same portion of reality,” of which composition and numerical identity are distinct species. Composition is a genuine kind of identity; but unlike numerical identity, it fails to satisfy Leibniz’s Law. A composite whole and its parts differ with respect to their numerical properties: the whole is one; the parts are many. Moderate composition as identity faces the challenge: how, in the absence of Leib…Read more
  •  53
    Is There a Humean Account of Quantities?
    Philosophical Issues 27 (1): 26-51. 2017.
    Humeans have a problem with quantities. A core principle of any Humean account of modality is that fundamental entities can freely recombine. But determinate quantities, if fundamental, seem to violate this core principle: determinate quantities belonging to the same determinable necessarily exclude one another. Call this the problem of exclusion. Prominent Humeans have responded in various ways. Wittgenstein, when he resurfaced to philosophy, gave the problem of exclusion as a reason to a…Read more
  •  21
    Philosophical Perspectives on Newtonian Science (edited book)
    with R. I. G. Hughes
    MIT Press. 1990.
    These original essays explore the philosophical implications of Newton's work.
  •  124
    McGinn on Non-Existent Objects and Reducing Modality
    Philosophical Studies 118 (3): 439-451. 2004.
    In this discussion of Colin McGinn's book, 'Logical Properties', I comment first on the chapter "Existence", then on the chapter "Modality." With respect to existence, I argue that McGinn's view that existence is a property that some objects have and other objects lack requires the property of existence to be fundamentally unlike ordinary qualitative properties. Moreover, it opens up a challenging skeptical problem: how do I know that I exist? With respect to modality, I argue that McGinn's argu…Read more
  •  128
    The Fabric of Space: Intrinsic vs. Extrinsic Distance Relations
    Midwest Studies in Philosophy 18 (1): 271-294. 1993.
    In this chapter, I evaluate various conceptions of distance. Of the two most prominent, one takes distance relations to be intrinsic, the other extrinsic. I recommend pluralism: different conceptions can peacefully coexist as long as each holds sway over a distinct region of logical space. But when one asks which conception holds sway at the actual world, one conception stands out. It is the conception of distance embodied in differential geometry, what I call the Gaussian conception. On this co…Read more
  •  140
    Realism without parochialism
    In Modal Matters: Essays in Metaphysics, Oxford University Press. pp. 40-76. 2020.
    I am a realist of a metaphysical stripe. I believe in an immense realm of "modal" and "abstract" entities, of entities that are neither part of, nor stand in any causal relation to, the actual, concrete world. For starters: I believe in possible worlds and individuals; in propositions, properties, and relations (both abundantly and sparsely conceived); in mathematical objects and structures; and in sets (or classes) of whatever I believe in. Call these sorts of entity, and the reality they compr…Read more
  •  36
    In Donald Borchert (ed.), The Encyclopedia of Philosophy Supplement, Simon and Schuster Macmillan. 1996.
  •  64
    Absolute time versus absolute motion: Comments on Lawrence Sklar
    In Phillip Bricker & R. I. G. Hughes (eds.), Philosophical Perspectives on Newtonian Science, Mit Press. pp. 77--91. 1990.
    An attempt to clarify how the problem of absolute time and the problem of absolute motion relate to one another, especially with respect to causal attributions involving time and motion.
  •  142
    Truthmaking: With and Without Counterpart Theory
    In Barry Loewer & Jonathan Schaffer (eds.), The Blackwell Companion to David Lewis, Blackwell. 2015.
    According to the Truthmaker Principle: every truth has a truthmaker. Attempts to come to grips with the Truthmaker Principle played a prominent role in Lewis’s metaphysical writings over the last fifteen years of his career. Although Lewis agreed that the truth of propositions must somehow be ontologically grounded, the Truthmaker Principle was too strong: it conflicted with two of Lewis’s most fundamental metaphysical assumptions, the uniqueness of composition and the Humean denial of necessary…Read more
  •  121
    Review of Travels in Four Dimensions: The Enigmas of Space and Time (review)
    British Journal for the Philosophy of Science 57 (2): 453-458. 2006.
  •  25
    In Donald Borchert (ed.), The Encylopedia of Philosophy Supplement, Simon and Schuster Macmillan. 1996.
  •  18
    Review of The Concept of Time (review)
    Philosophical Review 106 (4): 629-632. 1997.
    Part 2 is concerned, in chapter 4, with semantic features of dates and duration terms, and, in chapter 5, with the conventionality of measurements of duration, and the incoherence of durationless instants.
  •  457
    Composition as a Kind of Identity
    Inquiry: An Interdisciplinary Journal of Philosophy 59 (3): 264-294. 2016.
    Composition as identity, as I understand it, is a theory of the composite structure of reality. The theory’s underlying logic is irreducibly plural; its fundamental primitive is a generalized identity relation that takes either plural or singular arguments. Strong versions of the theory that incorporate a generalized version of the indiscernibility of identicals are incompatible with the framework of plural logic, and should be rejected. Weak versions of the theory that are based on the idea tha…Read more
  •  1916
    Concrete possible worlds
    In Theodore Sider, John Hawthorne & Dean W. Zimmerman (eds.), Contemporary Debates in Metaphysics, Blackwell. pp. 111--134. 2008.
    In this chapter, I survey what I call Lewisian approaches to modality: approaches that analyze modality in terms of concrete possible worlds and their parts. I take the following four theses to be characteristic of Lewisian approaches to modality. (1) There is no primitive modality. (2) There exists a plurality of concrete possible worlds. (3) Actuality is an indexical concept. (4) Modality de re is to be analyzed in terms of counterparts, not transworld identity. After an introductory section i…Read more
  •  118
    In sections 1 through 5, I develop in detail what I call the standard theory of worlds and propositions, and I discuss a number of purported objections. The theory consists of five theses. The first two theses, presented in section 1, assert that the propositions form a Boolean algebra with respect to implication, and that the algebra is complete, respectively. In section 2, I introduce the notion of logical space: it is a field of sets that represents the propositional structure and whose space…Read more
  •  173
    If realism about possible worlds is to succeed in eliminating primitive modality, it must provide an 'analysis' of possible world: nonmodal criteria for demarcating one world from another. This David Lewis has done. Lewis holds, roughly, that worlds are maximal unified regions of logical space. So far, so good. But what Lewis means by 'unification' is too narrow, I think, in two different ways. First, for Lewis, all worlds are (almost) 'globally' unified: at any world, (almost) every part is dir…Read more
  •  97
    The Methodology of Modal Logic as Metaphysics
    Philosophy and Phenomenological Research 88 (3): 717-725. 2014.
  •  145
    Plenitude of Possible Structures
    Journal of Philosophy 88 (11): 607-619. 1991.
    Which mathematical structures are possible, that is, instantiated by the concrete inhabitants of some possible world? Are there worlds with four-dimensional space? With infinite-dimensional space? Whence comes our knowledge of the possibility of structures? In this paper, I develop and defend a principle of plenitude according to which any mathematically natural generalization of possible structure is itself possible. I motivate the principle pragmatically by way of the role that logical possibi…Read more
  •  618
    David Lewis's book 'On the Plurality of Worlds' mounts an extended defense of the thesis of modal realism, that the world we inhabit the entire cosmos of which we are a part is but one of a vast plurality of worlds, or cosmoi, all causally and spatiotemporally isolated from one another. The purpose of this article is to provide an accessible summary of the main positions and arguments in Lewis's book.
  •  94
    Quantified Modal Logic and the Plural De Re
    Midwest Studies in Philosophy 14 (1): 372-394. 1989.
    Modal sentences of the form "every F might be G" and "some F must be G" have a threefold ambiguity. in addition to the familiar readings "de dicto" and "de re", there is a third reading on which they are examples of the "plural de re": they attribute a modal property to the F's plurally in a way that cannot in general be reduced to an attribution of modal properties to the individual F's. The plural "de re" readings of modal sentences cannot be captured within standard quantified modal logic. I …Read more
  •  157
    Reducing possible worlds to language
    Philosophical Studies 52 (3). 1987.
    The most commonly heard proposals for reducing possible worlds to language succumb to a simple cardinality argument: it can be shown that there are more possible worlds than there are linguistic entities provided by the proposal. In this paper, I show how the standard proposals can be generalized in a natural way so as to make better use of the resources available to them, and thereby circumvent the cardinality argument. Once it is seen just what the limitations are on these more general proposa…Read more
  •  276
    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 confe…Read more