ABSTRACT
In traditional philosophical discussions, the following sorts of entities have at one time or another been deemed universals: qualities, quantities, kinds, types, forms, properties, relations, categories, general ideas, concepts. If we are permitted to simplify matters, we may distinguish two main traditional uses of the expression ‘universal’ – one quite restricted, the other more liberal. According to the restricted use, universals form a privileged subset of entities of the indicated types, namely, those that play a fundamental (maximally ‘basic’ or perfectly ‘natural’) role in the ultimate constitution of reality. In this connection, they are thought to be the entities suitable for ultimate general explanations. They are also thought to underlie genuine resemblances and, as such, are supposed to be ‘repeatable’ entities and so in that sense ‘universal’. (It should be noted that these criteria are not equivalent: for example, there evidently are perfectly ‘natural’ properties that are not repeatable, e.g. being an absolutely perfect being, being an even prime.)
According to the more liberal use, universals are the sorts of entities expressed by meaningful linguistic predicates and, relatedly, which are the predicate entities of propositions. There is no general constraint that they need to be fundamental (‘basic’ or ‘natural’): for example, such properties as the property of being a parricide – what Locke would call mixed modes – qualify as universals on this use. Accordingly, such properties need not play a privileged role in explanation. Nor must universals always underlie resemblances (and so be ‘repeatable’).
