In This Article Expand or collapse the "in this article" section Modality

  • Introduction
  • General Overviews
  • Anthologies
  • Logic
  • Linguistic Theories
  • Conventionalism
  • Non-Cognitive Theories
  • Possible Worlds
  • Counterpart Theory
  • Actualism
  • Combinatorialism
  • Modal Fictionalism
  • Modalism
  • Reference and Modality
  • Essentialism
  • Logical Necessity
  • Conceivability and Possibility

Philosophy Modality
Scott A. Shalkowski
  • LAST REVIEWED: 29 June 2011
  • LAST MODIFIED: 29 June 2011
  • DOI: 10.1093/obo/9780195396577-0077


The problems of modality––the modes of being or modes of truth––have a long history, stretching back at least as far as the Greeks. Over time, philosophers have distinguished families of modality: logical, metaphysical, natural, temporal, deontic, epistemic, doxastic, and dynamic. Treatments of these modes have been both formal and philosophical. This entry emphasizes the philosophical and the metaphysical, beginning with more “traditional” approaches (Linguistic Theories, Conventionalism, and Non-Cognitive Theories) before moving on to what many see as a definite step forward in understanding modality (Possible Worlds) and the specifics of that framework (Counterpart Theory). In reaction, there have been attempts to join aspects of traditional thought about modality with that advance (Actualism generally and more specific versions with Combinatorialism and Modal Fictionalism). Metaphysical issues are intertwined with issues of expressibility (Modalism, Reference and Modality), which are sometimes thought to track metaphysical issues (Essentialism) and whether there is a well-behaved modality that must be acknowledged or assumed and whether the most fundamental modality is metaphysically innocent (Logical Necessity). Finally, there is notable recent work on the epistemology of modality (Conceivability and Possibility).

General Overviews

Most introductions are relatively recent. Shalkowski 2006 concerns metaphysics, is compact, and covers more traditional approaches as well as possible worlds; Vaidya 2007 is available electronically and concerns epistemology. Melia 2003 and Girle 2003 are each introductory texts focused mainly on contemporary possible worlds theories. Sider 2003 is somewhat more advanced and narrower in its attention to possible worlds. Plantinga 1978 is a monograph that attempts a general metaphysics of modality to be applied to traditional philosophical problems. Forbes 1985 provides a somewhat more technical overview of the logical background of much contemporary work as well as defenses of essentialist claims, and Jubien 2009 breaks with the possible worlds tradition to provide a rather different account of modality.

  • Forbes, G. The Metaphysics of Modality. Clarendon Library of Logic and Philosophy. Oxford: Clarendon Press, 1985.

    Provides the logical background for modal metaphysics. Discusses the modal de re/de dicto distinction and offers a modal theory of essential properties for sets, organisms, artifacts, substances, and events. The work ends with a conceptualist account of modality.

  • Girle, R. Possible Worlds. Chesham, UK: Acumen, 2003.

    Aimed at advanced undergraduates and postgraduates. A quite gentle but thorough introduction to modal discourse and logics. Heavy emphasis on the possible worlds semantics. Chapters on epistemic, doxastic, and temporal logics, metaphysics, and impossible worlds.

  • Jubien, M. Possibility. Oxford: Clarendon Press, 2009.

    Attempts an account of modality without recourse to possible worlds. Relies instead on physical objects, properties, relations, and entailment. Covers essentialism, natural kind terms, proper names, and the necessary a posteriori.

  • Melia, J. Modality. Central Problems of Philosophy. Chesham, UK: Acumen, 2003.

    An accessible introduction to modal notions, very elementary modal logic, and the possible worlds semantics. Contains discussions of foundational issues, including Quinean modal skepticism and the nature of possible worlds. Defends a linguistic approach to possible worlds as more promising than alternatives.

  • Plantinga, A. The Nature of Necessity. Clarendon Library of Logic and Philosophy. Oxford: Clarendon Press, 1978.

    DOI: 10.1093/0198244142.001.0001

    One of the first book-length philosophical treatments of modality. Develops an account of possible worlds in terms of states of affairs, identity across possible worlds, de re modality, and names, to accommodate negative existential claims and merely possible objects. Applications made to the Problem of Evil and the Ontological Argument.

  • Shalkowski, S. “Modality, Philosophy and Metaphysics of.” In Encyclopedia of Philosophy. 2d ed. Edited by D. Borchert. 2006.

    An introductory survey essay covering kinds and sources of necessity, possible worlds and modal logic, possible worlds and metaphysics, fictionalism, modalism, and warrant for metaphysical claims. Ten-volume e-book.

  • Sider, T. “Reductive Theories of Modality.” In The Oxford Handbook of Metaphysics. Edited by M. Loux and D. Zimmerman, 180–208. Oxford: Oxford University Press, 2003.

    A survey of reductive strategies for modality. Includes David Lewis’s modal realism, ersatzism about possible worlds, Armstrong’s combinatorialism, modal fictionalism, and conventionalism.

  • Vaidya, Anand, “The Epistemology of Modality.” In The Stanford Encyclopedia of Philosophy. Edited by Edward N. Zalta. 2007.

    A lengthy introduction to the epistemology of modality. Useful bibliography. Argues for no position but provides a good survey of current positions as well as their major critiques.

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