Concepts, though fundamental, are only tools—only means to an end. The end is the practical, productive, rational use of your mind to achieve your values, secure your survival, and enhance your life. That is the topic of this course: four classes on using concepts to think—to think in the way that reaches rational conclusions. Thinking is in sentences—i.e., propositions. Combining theory with homework exercises, two classes contrast the logical and the illogical way to form propositions, then two classes deal with integrating propositions to reach new identifications of facts—i.e., induction and deduction. Emphasis is given to working on practical exercises. The course, recorded at OCON 2019, builds on Binswanger’s OCON 2018 course Logic: The Method of Reason.