A combination of lectures on and exercises in “the art of non-contradictory identification.” This course does not cover traditional logic but focuses instead on the uniquely Objectivist approach to logic—especially on Ayn Rand’s discoveries concerning the use and misuse of concepts. Since cognition is essentially differentiation and integration, and since the process of defining concepts is the archetype of differentiation and integration, emphasis will be placed on learning a specific, step-by-step method of formulating a valid definition. We will also cover: proper vs. invalid concepts; the fallacies of the “stolen concept” and “self-exclusion”; how to achieve unit-economy in propositions; and objective judgment vs. arbitrary assertions. “Homework” exercises will be given on each of the topics, and a sampling of students’ answers will be discussed in class. (This is a revised version of a 1993 course, which is not available on tape.)