Problem of Universals

1. Introduction

The Problem of Universals concerns how to understand general features of reality—such as properties, kinds, and relations—and their connection to individual things. When people say that two apples are both red, that many animals are mammals, or that various actions are just, they appear to attribute one and the same feature to many distinct items. The question is what, if anything, this shared “one” is.

Philosophers call such repeatable features universals, and individual objects that exemplify them particulars. The central issue is whether universals exist in any robust sense and, if so, what their mode of existence is and how they relate to the particular things that seem to “have” them.

This problem lies at the intersection of several branches of philosophy. In metaphysics, it raises questions about what kinds of entities populate the world. In the philosophy of language, it shapes theories of how general terms and predicates (such as “red” or “electron”) get their meaning and reference. In the philosophy of logic, it bears on the nature of quantification, predication, and logical form.

Historically, the problem has served as a focal point for broader commitments about knowledge, science, theology, and social life. Positions on universals often reflect deeper views about whether reality is fundamentally structured, whether our concepts track that structure, and how much of that structure is independent of human minds and practices.

The following sections survey the main formulations of the problem, trace its historical development from antiquity to contemporary analytic metaphysics, and map the principal positions and controversies that have emerged around it.

2. Definition and Scope of the Problem of Universals

The problem of universals arises from the apparent tension between the many and the one. On the one hand, there are many distinct objects; on the other, they seem to share the same properties or belong to the same kinds. The core issue is how to make sense of this sharing.

2.1 Universals and Related Notions

A standard definition characterizes a universal as a repeatable entity: something that can be “wholly present” in many different particulars. Redness, humanity, triangularity, and being taller than are typical examples used in the literature.

The problem typically encompasses:

• Properties (e.g., redness, mass)
• Relations (e.g., being larger than, being a sibling of)
• Kinds or types (e.g., electron, oak tree, justice as a virtue)
• Sometimes structures and patterns (e.g., symmetries, functional roles)

By contrast, particulars are non-repeatable individuals: this apple, that electron, this person.

2.2 Questions Within the Scope

While the overarching concern is metaphysical, the problem branches into more specific questions:

2.3 Limits of the Problem

The Problem of Universals is narrower than the general problem of abstract objects, though many accounts link them. It is also distinct from, though related to, debates about vagueness, individuation, and identity over time. This entry focuses specifically on the status of repeatable features and kinds, leaving broader issues of abstraction and ontology to related topics.

3. The Core Question: Do Universals Exist?

At the heart of the debate lies a yes-or-no question: Are there universals in reality, or are there only particular things plus our ways of speaking and thinking about them? From this divide, the major families of views are typically defined.

3.1 Realist Answers

Realists about universals affirm their existence. They hold that when many particulars are all F (red, human, or charged), this is because there is something literally the same—a universal F-ness—present in each.

Two influential realist variants are:

Realists often argue that universals are needed to explain exact similarity, laws of nature, and the objectivity of mathematics and logic.

3.2 Anti-Realist Answers

Anti-realists about universals—broadly including various forms of nominalism and conceptualism—deny that there are universals in the realist’s sense.

• Nominalists maintain that there are only particulars, plus perhaps classes, sets, or resemblance relations, but no repeatable entities over and above these.
• Conceptualists hold that general features exist only as mental contents or concepts, not as mind-independent universals.

Anti-realists typically seek to account for our use of general terms and apparent shared properties through linguistic practice, classification, or mental representation.

3.3 Intermediate or Alternative Framings

Some theories, such as trope theory and certain forms of resemblance nominalism, neither fully endorse traditional realism nor straightforwardly deny generality. They reframe the core question: instead of asking whether universals exist, they ask whether particularized properties or primitive resemblance relations can do the explanatory work universals were thought to perform.

The subsequent sections unpack how this core question was first articulated, how it has evolved historically, and what specific answers have been proposed.

4. Historical Origins in Ancient Philosophy

Ancient Greek philosophy provides the first sustained treatments of issues later grouped under the Problem of Universals. While the terminology of “universals” develops later, classical authors grapple with how general terms relate to what exists and how many things can be “one in kind.”

4.1 Pre-Socratic and Sophistic Background

Pre-Socratic thinkers introduce contrasts between the one and the many, permanence and change, which later frame questions about shared natures. Parmenides emphasizes unchanging being, while Heraclitus stresses flux, leading to concerns about how stable kinds can exist in a changing world.

Sophists and early rhetoricians explore the use of general terms in argument and classification, highlighting the gap between words and things and preparing the ground for more systematic treatments.

4.2 Plato’s Pioneering Formulation

In dialogues such as the Phaedo, Republic, and Parmenides, Plato introduces Forms (or Ideas) as paradigmatic realities that many particular things “participate in.” When several things are beautiful or just, Plato suggests that they are so by partaking in the Form of Beauty or Justice itself.

Plato’s discussions raise canonical questions later associated with universals:

• How do we explain sameness across many instances?
• What is the relation between Forms and sensible particulars?
• How can we have knowledge of general, unchanging realities?

4.3 Aristotle’s Critique and Reformulation

Aristotle reacts critically to Platonic Forms, especially in the Metaphysics, while preserving an objective sense of shared natures. He develops the notion of common natures—such as humanity—that are instantiated in individual substances and analyzed through genus and species.

Aristotle’s logic, especially in the Categories and Prior Analytics, systematically treats predication (saying “S is P”) and the distinction between universal and particular terms, making explicit that something can be “said of many.” This becomes a key conceptual resource for later debates.

4.4 Hellenistic and Late Antique Developments

Stoic logicians and metaphysicians elaborate theories of lekta (sayables) and common notions, while often resisting robust Platonic universals. Porphyry’s Isagoge (Introduction to Aristotle’s Categories), and Boethius’s later Latin commentaries, formulate explicit questions about the status of genera and species—questions that medieval thinkers will identify as the problem of universals proper.

5. Plato’s Theory of Forms and Extreme Realism

Plato’s theory of Forms is frequently interpreted as a paradigmatic form of extreme (Platonic) realism about universals. On this reading, universals are fully real, independent entities that particulars somehow participate in.

5.1 Ontological Status of Forms

In dialogs like the Phaedo and Republic, Plato portrays Forms as:

• Non-spatiotemporal: not located in space or time.
• Immutable and perfect: unlike their imperfect sensible instances.
• Ontologically prior: more real than the changing particulars that imitate them.

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“We are in the habit of positing one single Form for each of the many things to which we apply the same name.”

— Plato, Phaedo (approximate paraphrase)

On this interpretation, the Form of Beauty or Equality is a universal that many things can share without being identical to it.

5.2 Participation and Exemplification

Plato explains similarity by appeal to participation (methexis): a particular is beautiful by participating in the Form of Beauty. The nature of this relation is left partly obscure, leading to later puzzles. Nonetheless, participation is meant to ground:

• The unity of a universal across many instances.
• The objectivity of evaluative and mathematical truths.
• The possibility of knowledge of general features, since the Forms are fixed and intelligible.

5.3 The Third Man and Self-Critique

In the Parmenides, Plato exposes difficulties in his own theory, including the famous Third Man Argument: if a group of large things are large by participating in the Form of Largeness, and the Form itself is large, then a further Form seems required to explain the similarity between the first Form and its instances, generating a regress.

This self-critical turn raises questions about:

• Whether treating universals as separate entities leads to infinite chains of higher-order Forms.
• Whether the participation relation is intelligible.

5.4 Legacy of Platonic Realism

Later Platonists, Neo-Platonists, and many modern defenders of abstract objects (especially in the philosophy of mathematics) draw on Platonic themes, though they often reinterpret “Forms” as generic abstract universals rather than as metaphysically exalted, quasi-divine realities. The core idea remains that universals exist independently of both particular objects and human minds.

6. Aristotle’s Immanent Universals and Moderate Realism

Aristotle offers an alternative to Platonic extreme realism, often described as immanent or moderate realism. He accepts that there are shared natures but denies that they exist separately from the particulars that instantiate them.

6.1 Universals in Substances

In works such as the Categories and Metaphysics, Aristotle distinguishes primary substances (individuals like Socrates) from secondary substances (species and genera like human or animal). Secondary substances are universal in that they can be predicated of many individuals, but they do not exist in a separate realm.

For Aristotle:

• Universals are “in” things as their natures or forms.
• An individual human is a composite of matter and form; its humanity is the universal form instantiated in that particular.

6.2 Predication and “Said of Many”

Aristotle’s logical works define universals through predicability: a universal is what can be said of many. This ties universals to the structure of scientific explanation, where we state what belongs to things qua members of a species or genus.

6.3 Science, Definition, and Essence

In the Posterior Analytics, Aristotle links universals to demonstrative science. Scientific knowledge concerns the necessary and universal features of things, captured in definitions (e.g., “human is a rational animal”). These definitions express the essence of a kind, which is the universal form.

Thus, universals:

• Ground laws and explanatory generalizations.
• Provide the essences that make classification objective.

6.4 Debates Over Aristotle’s Realism

Interpreters disagree on how robust Aristotle’s commitment to universals is. Some read him as endorsing genuinely distinct universals immanent in particulars; others emphasize that form is primarily a principle of organization within individuals, making his realism more moderate or even proto-nominalist. Medieval and contemporary Aristotelians develop these themes into systematic accounts of immanent universals.

7. Medieval Debates: Realism, Nominalism, and Conceptualism

Medieval thinkers transform ancient discussions into a self-conscious “question of universals” (quaestio de universalibus), especially through commentaries on Porphyry’s Isagoge and Boethius’s translations and glosses.

7.1 Framing the Question

Porphyry famously raises, and declines to answer, three questions about genera and species:

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“I shall not now say whether genera and species subsist in the nature of things, or are only in the understanding; nor, if they subsist, whether they are corporeal or incorporeal, and whether they are separated or in sensibles and about them.”

— Porphyry, Isagoge (via Boethius)

These questions become the standard template for medieval debate: Are universals real, where do they exist, and how do they relate to particulars?

7.2 Medieval Realisms

Figures such as Thomas Aquinas and Duns Scotus develop sophisticated realist positions, often influenced by Aristotle:

• Aquinas holds that universals exist in three ways: in God’s mind (as divine ideas), in things (as instantiated natures), and in human minds (as abstracted concepts).
• Scotus emphasizes the formal distinction between an individual and its nature, allowing one and the same nature (e.g., humanity) to be common to many while still individuated in each.

These accounts aim to preserve the objectivity of scientific and theological knowledge.

7.3 Nominalist Challenges

From the 14th century, nominalist positions gain prominence, especially with William of Ockham and later Franciscan thinkers:

• Ockham denies extra-mental universals; only individuals exist.
• General terms signify many particulars by being commonly predicable, not by naming a shared entity.

Nominalists argue that realist ontologies are unnecessarily inflated and that logical and scientific practices can be explained using only particulars, signs, and mental acts.

7.4 Conceptualist Accounts

Some approaches, often labeled conceptualist, assign universals to the realm of the mind:

• Peter Abelard interprets universals as status or conditions of things, while emphasizing the role of language and mental representation.
• Later scholastics explore how the intellect forms universal concepts by abstraction, which are then signified by general terms.

Conceptualism seeks a middle path: maintaining a robust role for universal concepts in thought without positing universals as independent entities.

7.5 Diversity and Influence

Medieval discussions are highly technical and varied, involving distinctions between first and second intentions, material and formal aspects of universals, and differing logics of supposition. These debates deeply influence subsequent scholasticism and shape early modern responses to the problem.

8. Early Modern Transformations and Empiricist Challenges

In the early modern period, the Problem of Universals is reframed in light of new scientific methods, epistemological concerns, and theological shifts. While explicit scholastic language recedes, questions about general ideas, essences, and classification remain central.

8.1 Rationalist Reinterpretations

Rationalist philosophers maintain strong commitments to general truths but often reconceive universals:

• Descartes speaks of clear and distinct ideas and innate concepts, sometimes interpreted as a form of conceptualist realism: universals are grounded in the structure of the mind, which reflects divine perfection.
• Leibniz emphasizes the conceptual containment of predicates in subjects and an infinite network of logical relations between concepts. Universals appear as ideal entities or “possibles” grounded in God’s intellect, supporting a version of theological realism about abstract structures.

8.2 Empiricist Nominalist Tendencies

Empiricist thinkers express more explicitly nominalist or conceptualist sympathies.

John Locke characterizes general ideas as formed by abstraction from particular experiences. General terms stand for these abstract ideas rather than for mind-independent universals. He remains cautious about strong metaphysical claims regarding essences, distinguishing:

David Hume radicalizes empiricism by questioning whether our idea of a universal is anything more than a “custom of imagination” treating similar impressions as the same. He is frequently read as advocating a form of resemblance nominalism or psychologized conceptualism.

8.3 Scientific and Taxonomic Context

The rise of modern science and natural history brings new attention to natural kinds and classification:

• Debates arise over whether species (biological or chemical) have real essences, or whether classifications are largely conventional.
• Early modern mechanics and corpuscularianism encourage a focus on microscopic structure rather than Aristotelian forms.

These developments pressure traditional realist accounts while also motivating some thinkers to defend robust structures (e.g., mathematical entities, laws) as indispensable to science.

8.4 Decline of Scholastic Frameworks

As scholastic metaphysics loses institutional dominance, the problem of universals is less often framed in its traditional terms. Instead, it appears under headings such as general ideas, abstract objects, and essence, setting the stage for its re-emergence in 19th- and 20th-century logic and analytic philosophy.

9. Analytic Metaphysics and Contemporary Positions

In the late 19th and 20th centuries, the Problem of Universals is revived within analytic philosophy, closely linked to advances in logic and language.

9.1 Logical and Linguistic Reorientation

Gottlob Frege and Bertrand Russell introduce a powerful logical apparatus where predicates, quantifiers, and variables make explicit the structure of general statements. This raises fresh questions about what predicates (e.g., “is red”) stand for.

• Frege treats predicates as denoting concepts (a kind of function) and sometimes ascribes to them an abstract, non-psychological status.
• Russell initially develops a robust realism about universals, arguing that properties and relations must be part of the ontology to make sense of predication and logical form.

W. V. O. Quine later challenges some traditional realist and intensionalist accounts, while keeping a broad naturalistic ontology where acceptance of universals depends on their indispensability to scientific theory.

9.2 Neo-Realist Theories

Contemporary realists elaborate systematic accounts of universals:

• D. M. Armstrong defends a sparse immanent realism: only those universals needed to state the laws of nature are admitted, and they exist only in their instances.
• Michael Loux and E. J. Lowe develop Aristotelian-inspired frameworks where universals are integral to the structure of substances and categories.

9.3 Nominalist and Anti-Realist Approaches

Analytic nominalists and anti-realists explore alternatives:

• Nelson Goodman proposes an extreme nominalism, construing similarity and classification without positing universals, relying instead on predicates and “projectible” ways of grouping.
• Frank Ramsey and later philosophers offer deflationary views, treating talk of properties and universals as convenient shorthand for patterns in language or facts about particulars.

Trope theorists (see Section 11) propose particularized properties to avoid multiply located universals while preserving a realist flavor.

9.4 Modal, Mathematical, and Metaphysical Elaborations

The problem also interacts with:

• Modal metaphysics: David Lewis’s possible worlds and counterpart theory raise questions about cross-world identity of properties and kinds.
• Philosophy of mathematics: Alvin Plantinga, structuralists, and others debate the status of mathematical objects and sets, often invoking Platonic-style universals.

Contemporary work typically situates universals within a broader web of issues—truthmaking, laws of nature, natural kinds, and semantic reference—leading to a variety of finely differentiated positions rather than a simple realist/nominalist dichotomy.

10. Major Positions: Platonic and Aristotelian Realism

Classical realism about universals divides into two main forms: Platonic (extreme) realism and Aristotelian (immanent) realism. Both affirm the existence of universals but differ in their ontological status and relationship to particulars.

10.1 Platonic (Extreme) Realism

Platonic realists contend that universals are:

• Abstract: not located in space or time.
• Independent: their existence does not depend on whether they are instantiated in the physical world.
• Mind-independent: they exist regardless of human or divine cognition (though some theistic Platonists locate them in a divine intellect).

On this view:

• Particulars exemplify or participate in universals.
• Universals can exist uninstantiated (e.g., the property of being a unicorn could exist even if no unicorns do).

Proponents argue that this framework:

• Explains exact similarity (two red objects share the same redness).
• Grounds necessary truths in mathematics and logic.
• Provides clear referents for general terms and predicates.

Critics raise concerns about:

• Ontological extravagance: an enormous realm of abstract entities.
• The participation relation: how non-spatial universals relate to spatiotemporal particulars.
• Regress problems like the Third Man (see Section 16).

10.2 Aristotelian (Immanent) Realism

Aristotelian realists agree that universals are real but insist that they are:

• Immanent: existing only in or as aspects of the particulars that instantiate them.
• Typically instantiation-dependent: no free-floating, uninstantiated universals.

Key features:

• Universals are the natures or forms of things (e.g., humanity in individual humans).
• Science investigates these natures through empirical study and abstraction.
• Universals play a direct role in causal explanations, since they are present in the causal agents and patients themselves.

Advantages claimed include:

• Greater ontological economy compared with Platonic realism.
• Closer alignment with scientific practice, where properties are always instantiated.

Challenges include:

• Explaining how one and the same universal can be wholly present in many distinct particulars.
• Accounting for necessary truths and uninstantiated possibilities (e.g., unrealized but physically possible properties).

10.3 Comparative Overview

Both forms of realism continue to inform contemporary debates, often in modified or hybrid versions.

11. Major Positions: Nominalism, Conceptualism, and Trope Theory

Opposed to realist views, various theories seek to explain generality without positing universals as repeatable entities. These include nominalism, conceptualism, and trope theory, which differ in where they locate or how they reconceive general features.

11.1 Nominalism

Nominalists deny that there are universals in the realist sense. The apparent sharing of a property is explained without appeal to a common entity.

Common strands include:

• Predicate nominalism: universality is a feature of language; “red” applies to many things, but there is no entity redness.
• Class nominalism: talk of a universal is reducible to talk of a set or class of particulars.
• Resemblance nominalism: similar objects are grouped because they stand in primitive or analyzable resemblance relations, not because they share a universal.

Nominalists often stress:

• Ontological parsimony: only particulars (and perhaps sets) are needed.
• Better fit with naturalism: all entities are spatiotemporal or reducible to such.

Difficulties frequently discussed include:

• Explaining exact similarity and objective classification without invoking shared entities.
• Avoiding a regress where resemblance relations themselves seem to behave like universals.

11.2 Conceptualism

Conceptualists locate universality primarily in the mind:

• Universals exist as general concepts or ideas that can apply to many particulars.
• General terms refer to these concepts, which we form by abstraction, comparison, or other cognitive operations.

Conceptualists emphasize:

• The role of cognitive capacities in structuring experience.
• The intersubjective nature of concepts: multiple subjects can share similar conceptual schemes.

Challenges include:

• Maintaining the objectivity of properties and scientific kinds if universals are mind-dependent.
• Explaining how concepts themselves can have general content without reintroducing a form of realism about mental universals.

11.3 Trope Theory

Trope theory offers an alternative by positing particularized properties or tropes:

• A trope is a concrete instance of a property, such as the specific redness of this apple.
• Similarity between objects is explained by resemblance among tropes, not by sharing a universal.

Key claims:

• Only particulars exist, but among them are property-particulars (tropes).
• Objects are bundles or structured combinations of tropes.
• This approach aims to secure a realist feel about properties while avoiding multiply located universals.

Issues debated include:

• How to group tropes into natural classes without invoking universals.
• Whether trope resemblance itself needs a higher-order universal.
• How tropes ground laws of nature and causal powers.

11.4 Comparative Summary

These positions provide a diverse array of anti-realist or alternative frameworks for addressing the phenomena that motivate belief in universals.

12. Semantic and Logical Aspects of Universals

The Problem of Universals is deeply intertwined with questions about language and logic, especially predication, quantification, and reference.

12.1 Predication and Logical Form

In standard predicate logic, statements like “All cats are mammals” have the form:

• ∀x (Cat(x) → Mammal(x))

Here, predicates (“Cat”, “Mammal”) apply to many objects, mirroring the idea of universals. Different metaphysical views interpret such predicates differently:

Logical theories generally remain neutral at the formal level, but semantic interpretation brings in commitments about universals.

12.2 Reference of General Terms

General terms (e.g., “red”, “electron”) and kind terms (“tiger”, “water”) raise questions of reference:

• Do they refer to universals, to sets of particulars, to concepts, or something else?
• How do they maintain reference across time and scientific change?

Different semantic theories connect here:

• Direct reference or Millian views for some terms see names or natural kind terms as linked directly to objects or kinds.
• Descriptivist or Fregean views tie meaning to associated senses or criteria, which may involve universals.

Realists often view general terms as denoting universals; nominalists may treat them as predicates with satisfaction conditions definable without universals.

12.3 Quantification Over Properties

Many logical systems allow second-order quantification over properties or sets (e.g., ∀F). The status of such quantification is contested:

• Realists often take it at face value, as quantification over real universals.
• Some nominalists reinterpret it as schematic or as quantification over linguistic expressions or sets.

Debates about second-order logic’s commitment to universals inform broader meta-ontological discussions.

12.4 Truthmakers and Logical Validity

Questions about what makes general statements true—their truthmakers—also implicate universals:

• For realists, universal generalizations (e.g., “All electrons have charge -e”) are made true by universals and their instantiations.
• For nominalists, truth may depend on patterns among particulars or on more complex truthmaking principles.

Logical relations such as inference and consequence can be analyzed in model-theoretic terms, but some philosophers argue that a satisfactory metaphysical account of universals is needed to ground logical structure in reality.

13. Universals, Science, and Natural Kinds

Scientific practice relies heavily on generalization, classification, and laws, all of which implicate the status of universals and natural kinds.

13.1 Natural Kinds and Classification

A natural kind is commonly understood as a grouping that reflects an objective structure in nature rather than a mere convenience. Examples include:

• Chemical kinds (e.g., gold, water).
• Biological species (e.g., Homo sapiens).
• Physical properties (e.g., mass, charge).

Realists about universals often identify natural kinds with universals or structured combinations thereof. Nominalists may regard kinds as clusters of similar particulars fixed by pragmatic or explanatory interests.

13.2 Laws of Nature

Laws of nature, such as “All bodies attract each other with a force proportional to their masses,” appear to quantify over properties and kinds. Competing accounts include:

• Universal-based views (e.g., Armstrong): laws are relations between universals (e.g., mass and acceleration).
• Regularity theories: laws are descriptions of patterns among particulars, without invoking universals.
• Modal or counterfactual accounts: laws are tied to what would happen under various conditions, raising questions about universals across possible worlds.

The choice among these affects whether scientific explanation presupposes universals.

13.3 Scientific Realism and Anti-Realism

Discussions about universals intersect with scientific realism:

Philosophers of science debate whether commitments to universals are justified by the success of scientific theories or whether weaker, nominalist-friendly ontologies suffice.

13.4 Biological and Social Species

In biology, the nature of species (and higher taxa) raises further questions:

• Essentialist views treat species as kinds with fixed essences (often interpreted as universals).
• Population and evolutionary perspectives treat species as historical lineages or gene pools, sometimes weakening the appeal to universals.

These debates overlap with discussions of social kinds (see Section 15), where the interaction between natural structure and human practices is even more complex.

14. Religious and Theological Dimensions

In religious and theological contexts, the Problem of Universals connects to doctrines about God, creation, and the status of abstract entities.

14.1 Divine Ideas and Exemplars

Many medieval Christian, Islamic, and Jewish philosophers adopt theological realism about universals via the notion of divine ideas:

• Universals are identified with exemplars in God’s intellect.
• Creation is understood as God instantiating these ideas in the world.

For example:

• Aquinas holds that universals pre-exist “in the mind of God” as patterns according to which creatures are made.
• Some Islamic philosophers (e.g., Avicenna) treat forms as having a threefold existence: in God’s intellect, in particular things, and in the human mind.

This framework integrates universals into a theocentric metaphysics.

14.2 Nominalism and Divine Omnipotence

Medieval nominalism has significant theological implications:

• By denying real universals, nominalists like Ockham emphasize God’s absolute power and the contingency of natural orders.
• Laws, natures, and species are not grounded in eternal universals but in God’s free will; God could have created a radically different order.

This can heighten a sense of divine freedom but raises questions about the rational intelligibility and stability of creation.

14.3 God and Abstract Objects

In contemporary philosophical theology, the status of universals intersects with debates about God’s relation to abstract objects:

• Theistic Platonists accept abstract universals but often say they are either identical with or dependent on God’s intellect.
• Others worry that independently existing universals compromise divine aseity (God’s self-existence), since God would then coexist with necessary abstract entities.

Responses include:

• Absolute creationism: God creates even abstracta, including universals.
• Modified divine conceptualism: universals are identical with divine concepts.

14.4 Religious Language and Universals

Theology also raises questions about universal predicates applied to God:

• Terms like “good,” “wise,” or “just” are used both of God and creatures.
• Realist accounts may posit a shared universal, modified by analogical predication.
• Nominalist or conceptualist approaches may instead focus on our mental or linguistic practices in attributing such properties.

Disagreements about universals thus influence theories of religious language, attributes of God, and participation in the divine.

15. Social Kinds, Politics, and Constructivist Readings

Beyond natural science, the Problem of Universals informs debates about social categories and political concepts such as race, gender, class, nation, and human rights.

15.1 Social Kinds and Their Ontology

Philosophers and social theorists ask whether social categories correspond to real universals, to constructed kinds, or to mere labels:

• Social realism about kinds holds that categories like “worker” or “citizen” pick out robust patterns and structures (institutions, roles, power relations) that might be treated as universals or structural properties.
• Social nominalism emphasizes that such categories depend entirely on human practices, norms, and language use.

15.2 Essentialism and Anti-Essentialism

The status of universals is central to debates about essentialism:

• Essentialist views treat certain social categories (e.g., gender or race) as reflecting underlying, possibly biological, essences.
• Anti-essentialist or constructivist positions reject fixed universal essences for these categories, stressing historical and cultural contingency.

Constructivist readings often argue:

• Social kinds are “interactive”: they change as people respond to being classified.
• The criteria for membership in such kinds are norm-governed and revisable.

15.3 Universality in Ethics and Politics

The idea of universal human rights or universal moral principles raises further questions:

• Are there moral universals—properties or norms that apply to all humans regardless of culture?
• Or are these “universal” claims best understood as aspirational constructs arising from particular historical contexts?

Different positions connect moral and political universality to:

• Realist moral properties (e.g., objective justice or dignity).
• Shared human nature (which itself may be treated as a universal).
• Or to overlapping consensus and political agreements without strong metaphysical commitments.

15.4 Intersection with Critical Theory

Critical theorists, feminist philosophers, and philosophers of race frequently scrutinize universal claims:

• Some criticize false universals that supposedly mask the standpoint of dominant groups.
• Others defend critical universals, such as universal personhood, as tools for resisting oppression.

These debates often hinge on whether universal categories can capture genuine commonalities without erasing difference, a question that mirrors traditional concerns about how one universal can be instantiated in many diverse particulars.

16. Objections, Regress Problems, and Ongoing Controversies

Across its history, the Problem of Universals has generated a range of objections and regress arguments that continue to structure contemporary debate.

16.1 The One-Over-Many and Third Man Regresses

Realists invoke universals to solve the one-over-many problem (what do many F things have in common?). Critics argue that this leads to regress:

• If particulars are F by participating in a universal F-ness, then the universal and its instances are all F.
• This seems to require a higher-order universal to explain their common F-ness, and so on ad infinitum (the Third Man style regress).

Realists respond by:

• Denying that each level requires a further universal.
• Treating the relation between universals and particulars as primitive or different in kind from similarity among particulars.

16.2 Resemblance and Resemblance Regress

Resemblance nominalism faces a parallel challenge:

• If similarity is taken as primitive, critics ask why certain similarities form natural groupings.
• If resemblance itself is a property, then similar objects are similar in virtue of sharing the property of resembling, which appears to be a universal of resemblance, reintroducing what nominalism sought to avoid.

Proposed solutions include:

• Hierarchies of resemblance relations.
• Treating resemblance as an unanalyzable primitive.

16.3 Companionship and Imperfection Problems

Sparse realist and nominalist views confront technical issues such as:

• The companionship problem: similar distribution patterns of predicates (e.g., “is grue” vs. “is green”) make it hard to pick out which correspond to genuine universals or natural kinds.
• The imperfect community problem: groups that share most but not all features pose challenges for resemblance-based or cluster accounts.

These problems press for more fine-grained criteria for naturalness or eligibility of properties.

16.4 Ontological Parsimony vs. Explanatory Power

A central, ongoing tension pits:

• Ontological parsimony (favored by many nominalists and naturalists) against
• Explanatory adequacy (invoked by realists to justify universals).

Debate continues over whether:

• Universals (or tropes) are indispensable for explaining laws, modality, and semantics.
• Or whether alternatives (e.g., structuralism, inferentialism, or deflationary truthmaking) can match their explanatory work without comparable commitments.

16.5 Modal, Higher-Order, and Metametaphysical Issues

Further controversies concern:

• Modal universals: properties of necessity, possibility, and dispositionality.
• Higher-order universals: properties of properties and potential higher-level regresses.
• Metametaphysical stances (e.g., quantifier variance, neo-Carnapianism) that question whether the debate is substantial or partly verbal.

There is no consensus resolution; instead, a complex landscape of positions persists, shaped by differing priorities about explanation, parsimony, and the aims of metaphysics.

17. Legacy and Historical Significance

The Problem of Universals has exerted a lasting influence on the development of Western philosophy and continues to inform contemporary debates across multiple subfields.

17.1 Shaping Metaphysical Traditions

Historically, positions on universals helped define major metaphysical traditions:

• Platonism and Aristotelianism developed, in part, through contrasting views on Forms and immanent universals.
• Medieval scholasticism organized much of its ontology, theology, and logic around realist, nominalist, and conceptualist options.
• Early modern rationalists and empiricists reshaped these issues into discussions of abstract ideas, essences, and general concepts.

These developments laid foundations for later analytic metaphysics.

17.2 Influence on Logic and Language

Debates about universals significantly influenced the philosophy of logic and language:

• Aristotle’s treatment of predication and categories.
• Medieval advances in supposition theory and modal logic.
• Modern formal logic’s concern with predicates, quantifiers, and second-order frameworks.

Questions about what predicates stand for and how general statements are grounded remain central to semantics and model theory.

17.3 Interdisciplinary Reach

The problem’s reach extends beyond core metaphysics:

These intersections show how abstract metaphysical disputes about universals can bear on concrete scientific, religious, and political questions.

17.4 Continuing Relevance

Contemporary philosophy still engages actively with universals:

• New versions of realism, nominalism, and trope theory are refined in light of truthmaker theory, modal logic, and scientific developments.
• Structuralist and deflationary approaches reconsider whether talk of universals is indispensable or reducible.

The historical trajectory of the Problem of Universals thus illustrates how a seemingly technical question—about what, if anything, many things share—can structure entire systems of thought and remain a live topic of research across changing philosophical eras.