Steven E. Schier is Dorothy H. and Edward C. Congdon Professor of Political Science Emeritus at Carleton College. He is the author or editor of 23 books including The Trump Effect: Disruption and Its Consequences in US Politics and Government and Polarized: The Rise of Ideology in American Politics, both with R&L. David A. Hopkins is associate professor of political science at Boston College. He is the author of Red Fighting Blue: How Geography and Electoral Rules Polarize American Politics (Cambridge University Press), and Asymmetric Politics: Ideological Republicans and Group Interest Democrats (Oxford University Press). His political analysis has appeared in the New York Times, Washington Post, and Vox, and he is a contributing columnist at Bloomberg Opinion. Nelson W. Polsby was Heller Professor of Political Science and past Director of the Institute of Governmental Studies at the University of California, Berkeley, where he taught American politics for forty years. Aaron Wildavsky was Class of 1940 Professor of Political Science and Public Policy at the University of California, Berkeley, and founding dean of Berkeley's Graduate (now Goldman) School of Public Policy.