Quine put this point in a very compelling way in connection with a conceptualistic view of mythical objects like Pegasus.    From Wordnik.com.  [Platonism in Metaphysics] Reference

First, there is the conceptualistic (or mentalistic) view that belief reports involve references to sentences in our heads, or mentalese sentence tokens.    From Wordnik.com.  [Platonism in Metaphysics] Reference

Hobbes, but Leibniz 'youthful nominalistic inclinations did not keep him from a conceptualistic theory of combinations, a connotative interpretation of logic, and an Augustinian theology.    From Wordnik.com.  [PERENNIAL PHILOSOPHY] Reference