Professor Ian Schnee describes the content of his course PHIL 120 Introduction to Logic. What makes an argument good? How do you show that someone has reasoned invalidly? In this course we will study arguments and reasoning both informally as well as with the tools and techniques of formal deductive logic. We learn the syntax and semantics of propositional and first-order logic (polyadic with identity), and we will use them to explicate the notion of a valid argument. We then apply our formal logical techniques to a variety of domains, such as the domain of sets (abstract collections of objects). Topics include syntax, semantics, pragmatics, consistency, proof, logical consequence, logical equivalence, logical truth, logical form, set theory, infinity, paradoxes, truth functionality, binary numbers, logic gates, truth tables, quantification, relations, functions, interpretations, models, soundness, and completeness. We will also discuss connections between formal logic and computability theory, philosophy of language, cognitive science, foundations of mathematics, and metalogic (theorems about logical systems themselves).