This is an introductory course in Symbolic Logic, or the art of formal reasoning. It should be of special value to anyone with an interest in mathematics, computer programming, the sciences, or philosophy. Students will learn how to work with various classical and modern formal languages such as syllogistic logic, propositional logic, modal logic, and quantificational logic, and develop the ability to think in any discipline with greater clarity, precision, and understanding. No philosophy prerequisites are needed for this course and, in particular, it is not necessary to have taken PHIL-I02, Principles of Logic, before enrolling in PHIL-104.