• 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
  • 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
  • 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
  • Absolute Actuality and the Plurality of Worlds
    Philosophical Perspectives 20 (1). 2006.
    According to David Lewis, a realist about possible worlds must hold that actuality is relative: the worlds are ontologically all on a par; the actual and the merely possible differ, not absolutely, but in how they relate to us. Call this 'Lewisian realism'. The alternative, 'Leibnizian realism', holds that actuality is an absolute property that marks a distinction in ontological status. Lewis presents two arguments against Leibnizian realism. First, he argues that the Leibnizian realist cannot a…Read more
  • Review of The Four-Category Ontology: A Metaphysical Foundation for Natural Science (review)
    Australasian Journal of Philosophy 87 (4): 675-678. 2009.
    No abstract
  • Review of The Concept of Time (review)
    Philosophical Review 106 (4): 629-632. 1997.
  • 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.
  • McGinn on Non-Existent Objects and Reducing Modality (review)
    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
  • 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
  • Properties
    In Donald Borchert (ed.), The Encyclopedia of Philosophy Supplement, Simon and Schuster Macmillan. 1996.
  • 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.
  • The Methodology of Modal Logic as Metaphysics
    Philosophy and Phenomenological Research 88 (3): 717-725. 2014.
  • Review: Harry C. Bunt, Mass Terms and Model-Theoretic Semantics (review)
    Journal of Symbolic Logic 53 (2): 653-656. 1988.
  • Identity
    In Donald Borchert (ed.), The Encylopedia of Philosophy Supplement, Simon and Schuster Macmillan. 1996.
  • 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
  • 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
  • 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
  • Concrete possible worlds
    In Theodore Sider, John Hawthorne & Dean W. Zimmerman (eds.), Contemporary Debates in Metaphysics, Blackwell. pp. 111--134. 2008.
  • The Relation Between General and Particular: Entailment vs. Supervenience
    In Dean Zimmerman (ed.), Oxford Papers in Metaphysics, vol. 3, Oxford University Press. pp. 251-287. 2006.
    Some argue, following Bertrand Russell, that because general truths are not entailed by particular truths, general facts must be posited to exist in addition to particular facts. I argue on the contrary that because general truths (globally) supervene on particular truths, general facts are not needed in addition to particular facts; indeed, if one accepts the Humean denial of necessary connections between distinct existents, one can further conclude that there are no general facts. When entailm…Read more
  • 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.
  • 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
  • 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
  • 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
  • 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.
  • Review of The Metaphysics of Modality (review)
    Philosophical Review 97 (1): 127-131. 1988.