Akhil Reed Amar, Yale law professor, continues his course on America's unwritten constitution by asking why the same two parties have dominated American politics since the 1850s. He traces party structure into written law itself, including balance requirements on independent agencies like the Federal Election Commission and the seating and committee rules of Congress. Amar then turns to political science, explaining Duverger's law and how single-member districts, mandated by statute since 1842, combined with having one president, one senator per seat, and one governor at a time, push the system toward a stable two-party equilibrium. He works through the wasted-vote logic that makes a ballot for a third-party candidate often help the voter's least favorite outcome, closing with a look back at Adams and Jefferson. The lecture runs about sixteen minutes and is organized into clear chapters.