universaux

Universaux, in philosophy, are properties, kinds or relations that can be instantiated by many different particular things. A universal such as redness, roundness, or humanity is said to be shared across multiple objects rather than belonging to a single thing. The central issue is whether universals exist independently of the things that have them, or whether they are merely names or concepts we use to group similar particulars.

Historically, the problem of universals traces to ancient Greece. Platonism holds that universals exist independently as abstract forms, accessible through intellect. Aristotle rejected that separation, arguing that universals exist only in things themselves (in re) and in the mind as terms or predicates that apply to many things. In the medieval period, realists such as Thomas Aquinas defended a form of realism where universals exist but are grounded in things, while conceptualists argued that universals exist only as mental concepts. Nominalists denied real universals altogether, claiming that only particular things and linguistic tokens are ontologically basic.

In contemporary philosophy, several positions have emerged. Trope theory treats properties as particularized instances (tropes) and denies universals as independent entities. Other approaches include resemblance nominalism, which explains universals through patterns of resemblance among individuals, and various realist or structuralist frameworks that relate universals to science, logic, and language. The debate also intersects with philosophy of language and logic, examining how universal terms function in predication and explanation.

The problem of universals remains a central topic in metaphysics, shaping discussions about language, science, and the nature of reality.