This course offers an introduction to the philosophy of international law. It begins with a survey of Aristotelian political theory, and its application in the work of influential scholars of international law, Francisco Vitoria (1483-1546) and Hugo Grotius (1583-1646). After fleshing out this “Scholastic” style of international law, we move to the heart of the course and a study of classical liberal international law. This examination begins with Thomas Hobbes (1588-1679) and Immanuel Kant (1724-1804), and the inclusion of their ideas in Emerich de Vattel’s (1714-1767) influential Eighteenth Century treatise on international law, and decisions from Justices John Marshall (1755-1835) and Joseph Story (1779-1845). The study of classical liberalism then shifts to its darker sides, and in particular, international law’s deep association with Nineteenth Century imperialism. The course concludes with an introduction to early Twentieth Century perspectives on international law, including post-colonial theory, the rise of international institutions, human rights, and the functionalist critique of the sovereign state. This course is intended as an introduction to the field of international law, and has no pre-requisites.