In this course we will examine partisan polarization in contemporary American politics and the forces producing and exacerbating it from a variety of perspectives: historical, political, social, economic and racial. We will go back to the framing of the American constitution and look at the history of the collapse of democracy in other societies, as well as at more general theories of how parties work and when they break down. The guiding aim will be to determine when and why political parties serve as instruments of democracy: two‐way transmission belts that convey communication between ordinary citizens and their representative elites; civil society organizations that allow for bottom‐up, spontaneous grass roots participation; schools of political socialization that train new citizens and potential leaders alike about issues, processes and the importance of fidelity to basic norms of constitutional democracy; etc. And we will also examine when and why parties stop playing these positive roles: what social, political, economic, cultural or demographic conditions produce political parties that prioritize the pursuit of power over their commitment to the democratic process itself and mobilize their supporters in ways that generate fear, anger and anxiety of a kind that make it hard to understand or hear the other side, let alone to respect them as fellow citizens? We will survey the rich contemporary literature on this topic, but also pay attention to historical theories from the 18th century forward. Having surveyed these issues, we will be in a position to determine the kinds of reform and change necessary if we are to produce a less fractious and poisonous, more deliberative and constructive politics in an America that stands, at once, on the cusp of finally realizing its democratic promise, and on the precipice of surrendering to the dark forces of division.