This course is an introduction to first-order logic. Logic is the study of the formal properties of arguments. In this course, we learn how to make arguments precise by formalizing sentences and applying methods of deductive reasoning to prove conclusions. We also discuss the relations between logical reasoning and informal reasoning, and logic and rationality. Why study logic? Logic gives you principles and techniques to distinguish good forms of reasoning, helps you to construct correct arguments, and (to some extent) think orderly. Additionally, logic is essential in other fields that you might also be interested in studying (e.g., mathematics, computer science, linguistics, and analytic philosophy). And of course, logic is a fun and interesting subject in its own right. The course presumes no background in philosophy or logic.