Nominalism is a family of positions in metaphysics and philosophy of language holding that abstract or general terms - such as “redness,” “humanity,” or “triangularity” - do not refer to independently existing entities, but are instead names, concepts, or linguistic conventions applied to collections of particular things. The precise scope and formulation of nominalism is itself contested: some definitions emphasize ontology (what exists), others emphasize semantics (what words refer to), and the boundary between nominalism and closely related positions such as conceptualism and trope theory remains a matter of ongoing philosophical debate. For a treatment of these definitional disputes, see nominalism-definition-debate.
Nominalism is standardly contrasted with realism about universals, the view that properties, kinds, or relations exist as genuine entities distinct from the particular things that instantiate them. Within analytic philosophy, the debate over universals remains active and unresolved. Contemporary nominalists typically argue that a parsimonious ontology - one that posits only particular, concrete individuals - is sufficient to account for the apparent regularities and resemblances in the world. Realists counter that without universals, it is difficult to explain how distinct particulars can genuinely share a property, or how mathematical and scientific truths can be objective.
Several varieties of nominalism are distinguished in current literature. Predicate nominalism holds that two things share a property simply by virtue of the same predicate applying to both, without any further ontological grounding. Resemblance nominalism grounds property-talk in objective similarity relations among particulars. Class nominalism identifies properties with sets or classes of individuals. Trope theory, sometimes called “abstract particulalism,” treats properties as particular rather than universal - a position that some classify as a form of nominalism and others treat as a distinct alternative. These internal distinctions are addressed in nominalism-varieties-debate.
In philosophy of mathematics, nominalism generates a distinctive challenge: if numbers and sets do not exist as abstract objects, an account must be given of why mathematics is so effective in describing the physical world. Fictionalist and modal-structural responses to this challenge remain actively debated. See mathematical-nominalism-fictionalism-debate.
* Nominalism is correct: only particulars exist. Defenders hold that positing universal entities violates ontological parsimony without explanatory gain, and that resemblance or predicate-application can do all the work attributed to universals. See nominalism-only-particulars-viewpoint.
* Realism about universals is correct. Critics of nominalism argue that genuine property-sharing and the objectivity of scientific kinds require entities that are not reducible to sets, predicates, or resemblance relations. See nominalism-realism-about-universals-viewpoint.
* Conceptualism as a middle position. On this view, universals exist, but only as concepts in minds rather than as mind-independent entities - distinguishing itself from both full-blooded realism and strict nominalism. See nominalism-conceptualism-viewpoint.
* Trope theory. Trope theorists accept that properties are real but deny they are universals, treating each instance of a property as a numerically distinct particular. The position is contested as to whether it counts as a form of nominalism or a separate ontological category. See nominalism-trope-theory-viewpoint.
* Fictionalism about abstracta. In philosophy of mathematics and beyond, fictionalists hold that talk of abstract objects is useful but not literally true - a position that extends nominalist commitments into domains such as mathematics and possible worlds. See nominalism-fictionalism-viewpoint.
* The problem of universals in medieval scholasticism. The condemnation of Roscelin of Compiègne's positions by the Council of Soissons (1092) and subsequent disputes between nominalist and realist factions within medieval universities constitute a documented institutional controversy with identifiable parties and records. See nominalism-medieval-controversy.
* Ockham's razor and its theological implications. William of Ockham's nominalist program generated formal ecclesiastical proceedings and charges of heresy, centering on whether his ontological commitments were compatible with Catholic doctrine on universals and divine ideas. See nominalism-ockham-theological-controversy.
* nominalism-history - History of nominalism from ancient antecedents through medieval, early modern, and contemporary developments * nominalism-definition-debate - Debate over how nominalism should be defined and demarcated from adjacent positions * nominalism-varieties-debate - Debate over the distinctions among predicate, resemblance, class, and trope-theoretic versions * nominalism-only-particulars-viewpoint - Viewpoint: nominalism correctly holds that only particulars exist * nominalism-realism-about-universals-viewpoint - Viewpoint: realism about universals * nominalism-conceptualism-viewpoint - Viewpoint: conceptualism as a middle position * nominalism-trope-theory-viewpoint - Viewpoint: trope theory * nominalism-fictionalism-viewpoint - Viewpoint: fictionalism about abstract objects * nominalism-medieval-controversy - Controversy: nominalism and realism in medieval scholasticism * nominalism-ockham-theological-controversy - Controversy: Ockham's nominalism and ecclesiastical censure * nominalism-realism-viewpoint-debate - Viewpoint Debate: nominalism vs. realism about universals * mathematical-nominalism-fictionalism-debate - Debate: fictionalism and the applicability of mathematics * Problem Of Universals - Main Topic: the problem of universals * realism-metaphysical - Main Topic: metaphysical realism * conceptualism - Main Topic: conceptualism * Trope Theory - Main Topic: trope theory * Philosophy of Mathematics - Main Topic: philosophy of mathematics
1. D. M. Armstrong, Universals and Scientific Realism, 2 vols. (Cambridge: Cambridge University Press, 1978). The standard contemporary defense of realism and systematic critique of nominalist alternatives. 2. Michael Devitt, “'Ostrich Nominalism' or 'Mirage Realism'?” Pacific Philosophical Quarterly 61, nos. 3-4 (1980): 433-439. Defense of a predicate-nominalist (“ostrich”) position. 3. David Lewis, On the Plurality of Worlds (Oxford: Blackwell, 1986), 50-69. Lewis's treatment of properties and his critical engagement with nominalism and class nominalism. 4. Gonzalo Rodriguez-Pereyra, Resemblance Nominalism: A Solution to the Problem of Universals (Oxford: Clarendon Press, 2002). The most sustained contemporary defense of resemblance nominalism. 5. Hartry Field, Science Without Numbers: A Defence of Nominalism (Princeton: Princeton University Press, 1980). The principal contemporary argument for nominalism in philosophy of mathematics. 6. D. C. Williams, “The Elements of Being,” Review of Metaphysics 7, no. 1 (1953): 3-18. Classic statement of trope theory. 7. John Marenbon, Early Medieval Philosophy (480-1150): An Introduction (London: Routledge, 1983), 98-105. On Roscelin and the Council of Soissons. 8. Marilyn McCord Adams, William Ockham, 2 vols. (Notre Dame: University of Notre Dame Press, 1987). Comprehensive treatment of Ockham's nominalism and its theological context. 9. Michael J. Loux, Metaphysics: A Contemporary Introduction, 3rd ed. (New York: Routledge, 2006), chaps. 1-2. Accessible survey of the problem of universals and the main positions.