John Duggan's Research Site
I am a professor of political science and economics at the University of Rochester, and a research associate of the W. Allen Wallis Institute of Political Economy. I was director of the Wallis Institute for the period 2002--2012, and I was co-managing editor for the journal Social Choice and Welfare for the period 2008--2015. I received my PhD in social science from the California Institute of Technology in 1995. My specializations are game theory, political economy, and social choice theory. My current work is on equilibrium existence in non-cooperative games, dynamic models of bargaining and elections, multi-dimensional spatial models of political competition, and informational aspects of voting and elections.
About my research
A mathematical model is a lens that can be helpful in aiding our understanding of a phenomenon, and as such, all models incorporate structure and assumptions that can color or distort that understanding. I tend to favor transparency, in the form of less restrictive assumptions, over resolution, even if that means trading off statistical analysis of testable hypotheses for general theoretical propositions. The main focus of my research has been the effect of dynamic and informational incentives on electoral and legislative politics, often using concepts from social choice theory as a benchmark for comparison and, sometimes, as a modeling tool. I've found political economy to be a rich source for theoretical problems: it turns out that discontinuities and non-convexities, which are often ruled out by assumption in economic theory, are a fundamental feature of politics. In some cases, this has led me to questions in pure game theory or social choice, e.g., the existence of equilibria in dynamic games, or the possibility of acyclic preference aggregation in the context of Arrow's impossibility theorem. Jeff Banks once told me that a theorist's choice of problems should follow his or her instincts: a problem should be chosen for its innate interest, not because it's easy or popular; in the long run, the interesting problems will reveal a more durable importance. The contents of this website reflect my attempt to pursue interesting problems, and to make a modest contribution to the field of theoretical political economy along the way.
In this section, I provide links to papers and other content added in the last year or so. Dates indicate the date of the post and sometimes differ from the date of the linked paper.
January 9, 2018 "Extreme Agenda Setting Power in Dynamic Bargaining Games" (2018) with Zizhen Ma. We investigate a canonical model of bargaining with a fixed agenda setter, and we show that when players are impatient or the set of alternatives is one-dimesional, the equilibrium outcome from the static model obtains; but when players are patient and the alternatives are multidimensional, the equilibrium outcome typically converges to the ideal point of the agenda setter.
January 9, 2018 "Weak Rationalizability and Arrovian Impossibility Results for Responsive Social Choice" (2018) I give representation theorems for choice functions satisfying weak rationality conditions, and I use these to deduce impossibility theorems for preference aggregation satisfying responsiveness conditions along with weak (or no!) rationality conditions. This paper is forthcoming in a special issue of Public Choice in honor of Kenneth Arrow.
June 15, 2017 “Subgame-Perfect Equilibrium in Games with Almost Perfect Information: Dispensing with Public Randomization” (with Paulo Barelli) Harris, Reny, and Robson (1995) show that correlated subgame perfect equilibrium exist in a general class of dynamic games. We show that when nature’s moves are atomless, every such equilibrium can be de-correlated: there is a payoff-equivalent subgame-perfect equilibrium of the original game. As a corollary, we obtain an existence result of He and Sun (2016) for subgame perfect equilibria in games with atomless moves by nature.
May 31, 2017 “Lobbying and Policy Extremism in Repeated Elections” (with Peter Bils and Gleason Judd) We investigate the effect of lobbying on policy choices in an infinite-horizon model of elections. We find that when the effectiveness of money is fixed, if office incentives become large, then policy choices converge to the median. However, if office incentives are fixed and the effectiveness of money becomes large, then polarized equilibria that exhibit arbitrarily extreme policy choices by all politician types can be supported. Here are some slides from a talk.
May 31, 2017 “Electoral Accountability and Responsive Democracy” (with Cesar Martinelli) We analyze a canonical two-period model of elections in which politicians’ preferences and actions are imperfectly observed by voters, i.e., elections are subject to adverse selection and moral hazard. We establish existence of electoral equilibrium, and we give a characterization of equilibria. We show that as politicians become more office motivated, policy is responsive to voter preferences in the sense that the expected level of effort exerted by politicians in the first period becomes arbitrarily large.
May 31, 2017 “Existence and Indeterminacy of Markovian Equilibria in Dynamic Bargaining Games” (with Vincent Anesi) We show that if certain gradient restrictions hold at an alternative, then when players are sufficiently patient, there is a continuum of equilibria with absorbing sets arbitrarily close to that alternative. Here is a longer working paper with a result that delivers a continuum of Pareto efficient equilibria. Here are some slides from a talk.
May 31, 2017 “The Political Economy of Dynamic Elections: Accountability, Commitment, and Responsiveness” (with Cesar Martinelli) This article is forthcoming at the Journal of Economic Literature. It contains a survey and synthesis of the literature on electoral accountability, i.e., repeated elections in which politicians cannot commit their policy choices. We focus on conditions under which policy choices of office holders nevertheless reflect the preferences of the median voter.
May 31, 2017 “The Political Economy of Dynamic Elections: A Survey and Some New Results” (with Cesar Martinelli) This is a longer version of the above JEL paper with expanded discussion and technical detail, including many proofs omitted from the shorter paper.
May 31, 2017 “Directional Equilibria” (with Hun Chung) We propose a new solution concept (directional equilibrium) for the multidimensional spatial model. We establish connections the core, Pareto optimality, existence, and generic local uniqueness and stability, and we provide non-cooperative foundations. Updates include expanded literature references and reduction of some technical material on generic properties of directional equilibria. Here is a working paper with results on generic properties, here are some slides from a longer talk, and here are slides from a shorter talk.