Among the many criticisms on Locke's use of the word Idea, this is the only one which, as it appears to me, precisely hits the mark; and I quote it for the additional reason that it precisely expresses the point of difference respecting the import of Propositions, between my view and what I have spoken of as the Conceptualist view of them.
"A System Of Logic, Ratiocinative And Inductive (Vol. 1 of 2)"
John Stuart Mill
Sometimes called the Conceptualist View.
"Logic, Inductive and Deductive"
William Minto
In other words, we tend to adopt the Conceptualist attitude, which regards individuals as the only reality, and universals as mental fictions.
"Kant's Theory of Knowledge"
Harold Arthur Prichard