Let's discuss the idea that there are no such things as properties, just lots of things which are more or less similar

The target claim asserts that property nominalism—by refusing to positing unneeded entities under a strict application of Ockham’s Razor—maintains alignment between our metaphysical commitments and empirical, naturalistic science. To evaluate this thesis at a university level, we must move past viewing nominalism as mere ledger-keeping or "ontological thrift." Instead, we must reconstruct it as a sophisticated meta-ontological framework. Below is the strongest, most charitable case for this position, systematically organized around four key theoretical dimensions. --- ### 1. Charitable Interpretation & Theoretical Foundations The nominalist argument rests on a methodological principle: **Metaphysical entities should be admitted into our total world-picture if and only if they play an irreducible explanatory role in our best empirical sciences.** ``` METAPHYSICAL NATURALISM / \ THE EPISTEMIC CONSTRAINT THE CAUSAL CONSTRAINT Knowledge requires physical Causal efficiency requires spatiotemporal interaction. spatiotemporal localization. \ / v v [ ONTOLOGICAL PARSIMONY ] (Rejection of Abstract Universals) ``` The advocate for naturalistic nominalism does not merely claim that "fewer entities is better." Rather, they assert two core thesis-level constraints: * **The Epistemic Constraint:** Human beings acquire knowledge through causal, information-bearing interactions between physical systems (brains/sensory apparatus) and the external world. Abstract universals (e.g., transcendent *Redness* or *Triangularity*) exist outside of space and time and lack causal powers. Therefore, positing them introduces an irreducible epistemic mystery: how could a spatiotemporal human mind ever access or confirm the existence of a non-spatiotemporal, non-causal abstractum? * **The Criterion of Ontological Commitment:** Following W.V.O. Quine’s foundational meta-ontology, a theory is committed to the existence of an entity if and only if that entity must be quantified over—must be a value of a bound variable—in the true, regimented statements of our best scientific theories. If physics can describe the state of the universe using only concrete spatiotemporal particulars (or physical fields and particles), then abstract properties are gratuitous additions. Under this charity, nominalism is not an *a priori* prejudice against abstract objects; it is the systematic application of scientific epistemology to metaphysics. --- ### 2. Formidable Advocates and Strongest Arguments The strength of this position is anchored in the work of several major analytic philosophers: * **W.V.O. Quine & Nelson Goodman:** In *Steps Toward a Constructive Nominalism* (1947), Quine and Goodman argued that admitting abstract entities into logic and metaphysics distorts language. Quine’s later naturalism emphasized that ontology must be determined from *within* our best empirical science, not dictated by traditional metaphysical intuitions. * **Hartry Field:** In *Science Without Numbers* (1980), Field targeted the strongest realist objection—the *Indispensability Argument*, which claims abstract entities (like mathematical objects) are required for physical theory. Field proved that major physical theories (such as Newtonian gravitation) can be formulated "nominally" without quantifying over mathematical abstracta, proving that science can proceed strictly via conservative nominalist representations. * **D.M. Armstrong’s Immanent Realism (as a baseline comparison):** Even realistic opponents of nominalism like Armstrong conceded the force of naturalism. Armstrong rejected Platonic (transcendent) universals because they violate physicalism, insisting instead that if universals exist, they must be *immanent*—wholly located where their instances are. Nominalism goes one step further in purging the remaining metaphysical bloat. #### Epistemic Grounding vs. Analogies | Dimension | Primary Evidence / Logical Grounding | Structural Analogy (Illustrative Only) | | :--- | :--- | :--- | | **Epistemic Access** | The Benacerraf-Field Problem: Abstract objects, being non-spatiotemporal, cannot emit photons, cause neural firings, or enter into informational loops with observers. | Positing abstract universals to explain physical similarity is like invoking invisible, non-physical ghosts to explain why two clocks tick at the same rate. | | **Explanatory Parsimony** | Tropes / Particulars: Causal interactions are entirely accounted for by concrete instances (e.g., *this* specific mass of *this* specific electron). | Positing "Electronhood" above and beyond all actual physical electrons adds an unnecessary middleman to theoretical physics. | --- ### 3. Addressing Weaknesses and Objections A sophisticated nominalist can readily defend the framework against standard philosophical objections: #### Objection A: "The Problem of One over Many" *Realist Objection:* How can two distinct objects (e.g., two red apples) both be "red" if there is no shared universal property of *Redness*? *Nominalist Response:* Particularist nominalisms (such as **Trope Theory** or **Resemblance Nominalism**) resolve this without abstract universals. Objects resemble one another not because they "partake" in an abstract universal, but because their individual, localized qualities (tropes) fall into primitive resemblance classes. Resemblance is an intrinsic relation between concrete particulars, requiring no overarching Platonic entity. #### Objection B: "The Indispensability of Abstract Mathematics in Physics" *Realist Objection:* Modern physics relies on differential equations and abstract vector spaces. Therefore, physics itself forces us to accept abstract entities. *Nominalist Response:* As Field demonstrated, mathematical structures are *nominalistically representational*—they function as convenient, conservative logical shorthand for complex spatial and physical relations among concrete objects. Mathematics simplifies our calculations, but the underlying physical realities consist entirely of concrete physical configurations. --- ### 4. Deep Metaphysical Synthesis When fully developed, the steel-manned nominalist position reveals that **realism about properties actually undermines scientific naturalism.** If a philosopher posits an unobservable, non-spatiotemporal, non-causal realm of universals to explain why concrete things have properties, they split reality into two incompatible realms: the physical world of empirical science and an ethereal world of abstract forms. Nominalism preserves the **unity of science**. By grounding all properties in concrete spatiotemporal particulars or tropes, nominalism ensures that everything that exists falls under the domain of empirical observation and physical causation. Ontological parsimony is therefore not merely about keeping the list of existing things short; it is about keeping our theory of reality coherent, naturalistic, and epistemically accessible.