Ranked Choice Voting, the Primaries System, and Political Extremism: Theory and Simulations
We compare political extremism among election winners in a model of ranked choice voting (RCV) to winners in a model of the currently predominant electoral system (CES) in the U.S., which is based on partisan primaries and plurality rule. In three candidate elections, extremism under RCV is always bounded below what it is under CES. However, this does not hold in elections with four or more candidates. Still, in these many-candidate elections, the winners under RCV tend to be less extreme than those under CES, though RCV's performance in electing moderate candidates relative to CES declines as the number of candidates increases. We show this by simulating a large number of elections for different distributions of voter ideology while varying the ideological positions of the candidates. We also examine the different variants of RCV as they are implemented in various American states and cities. We show that the Maine/NYC systems in which RCV is used in partisan primaries to nominate candidates for the general election are worse than not just the nonpartisan single-round RCV system (the "standard'' RCV system as implemented, for example, in Minneapolis and other municipal elections) but also worse than CES at electing moderate candidates. On the other hand, the Alaska variant in which a blanket nonpartisan primary is used to select the top four candidates that then compete in a general election in which RCV is used outperforms the standard RCV system. Out of all of the election systems that we study, we find that the top-two runoff system (the jungle primary system, as implemented in California, for example) is the best at electing moderate candidates, particularly when the total number of candidates is small (eight or less).
Avi Acharya is a professor of political science at Stanford University; a professor, by courtesy, of political economy at the Stanford Graduate School of Business; and senior fellow, by courtesy, at the Hoover Institution. He works in the fields of political economy and formal political theory.
His first book, Deep Roots: How Slavery Still Shapes Southern Politics (Princeton University Press, 2018), received the William H. Riker Award for the best book in political economy in 2019. His second book, The Cartel System of States: An Economic Theory of International Politics (Oxford University Press, 2023), provides a new understanding of the territorial state system as it developed through time and exists today.
His papers have been published in both economics and political science journals and have received awards such as the Elinor Ostrom best paper award, the Gosnell Prize in political methodology, and the Joseph Bernd best paper award. He is an editor at the journal Social Choice and Welfare and an advisory editor at Games and Economic Behavior.
He earned a PhD in political economy from Princeton University in 2012 and a BA in economics and mathematics from Yale University in 2006. Before joining the Stanford faculty, he taught in the economics and political science departments of the University of Rochester.