Modal logic began as the study of different sorts of modalities, or modes of truth: alethic ("it is necessarily true that"), epistemic ("it is known that"), deontic ("it ought to be the case that"), temporal ("it has always been the case that"), among others. By now, modal logic has become a broad area of research, forming a sort of lingua franca between many disciplines, especially philosophy, computer science, economics, and linguistics.

The course covers core concepts and basic metatheory of propositional modal logic, including relations to first-order logic; the basics of quantified modal logic; and selected applications of modal logic. Topics that may be discussed (the final choice of topics may be adapted to fit the interests of the students) include (dynamic) epistemic/doxastic logic, conditional logic, non-normal modal logics, logics of action and agency, temporal logics, and applications of modal logic in game theory. Students will come away from this course with a working knowledge of modal logic and its use in philosophy, computer science and game theory.