The Federalist remains the best single account of how American democracy is supposed to work. That said, it remains incomplete. While generations of scholars from Alexis de Tocqueville to Anthony Downs have worked hard to fill these gaps, America's constantly-changing society and political institutions continue to encounter new puzzles and challenges. We Hold These Truths provides a comprehensive survey of recent scholarship about the Framers' vision, stressing how long-established political patterns can abruptly change as voters become more polarized, and even lead to feedbacks that amplify public anger still further. Developing a theory of American democracy for the age of the internet, Trump, and polarization, this study mixes modern social science with a detailed knowledge of history, asking where the Framers' scheme has gone wrong - and what can be done to fix it.