The fate of human knowledge depends, ultimately, on a theory of concepts-on solving what philosophers traditionally called "the problem of universals." This lecture encapsulates the historical progression of philosophy's two false theories of concepts: intrinsicism and subjectivism. lntrinsicism, started by Plato and carried into religion by Augustine, argues that concepts exist in a supernatural reality, and that their meaning is grasped through some form of "revelation."Subjectivism, started by the Sophists and championed by Kant, argues that concepts are what ever an individual's or a group's consciousness wants them to be. Both theories sever concepts from any link to perceptual reality. And both end in emotionalism, thereby making all objective judgment impossible. Dr.Hull analyzes the intrinsicist and the subjectivist views of concepts by focusing on key statements of their philosophic originators and by examining their major historical turning points. He ends with a brief presentation of Objectivism's answer to these two theories.