Nominalism

In Metaphysics, Nominalism is the position that claims universals do not have an independent ontological status (i.e., they do not exist on their own).

Nominalists tend to think of universals, not as things-in-themsleves, but rather as entities that require the cognition of some agent; they are ideas in the mind of a thinker, not independently existing things.

The opposite of Metaphysical Realism.