Party Competition: An Agent-Based Model

Abstract

Chapters of a draft manuscript for a book under contract to the Princeton Studies in Complexity series of Princeton University PressChapter 5 presents findings on satisficing with imperfect information.The introductory chapter sets these findings in context.Any and all comments are profoundly welcome. This is a work in progress: please do not cite without the authors' permission.Versions of this work have been presented at seminars at: Trinity College, Dublin; European University Institute, Fiesole; London School of Economics; University of Bologna; New York University; Columbia University; University of Michigan; Emory University; MIT; Yale University; Duke University; Florida State University; and at the following conferences: Thanks are due for helpful comments from discussants and participants at all of these venues. CONTENTSIntroduction (c5000 words)1. Spatial dynamics of political competition (c4000 words).2. A baseline ABM of multidimensional, multiparty competition (c9000 words) 3. Methods and benchmarking (c18000 words) 4. Endogenous parties; interaction of diverse decision rules (c11000 words) Features of party decision rules (c11250 words)6. Evolutionary dynamics of decision rule selection (c8500 words) 7. Non-policy factors in party competition (c8500 words) 8. Party leaders with policy preferences (c8000 words) 9. Calibrating and testing dynamic models of party competition (c11000 words) Conclusion (c5000 words)References (c1500 words) Electronic Appendices: Supplementary materials on computational results and the full set of computer programs needed to replicate these, one program for each modeling chapter (Ch 2-8), for use and modification by readers Introduction A large part of politics in democratic societies is about the politics of representation. This has to do with how the needs and desires of ordinary citizens play a part in national decision-making, via the public representatives they choose in free and fair elections. A large part of representative politics is about party competition. This has to do with how a small number of organized political parties offer a distinctive and somewhat coherent set of options to voters, who then choose between alternative teams of public representatives. This is why understanding party competition is a core concern of people, be they professional political scientists or interested civilians, who care about politics in democratic societies.This book is about party competition. More specifically, it is about multi-party competition, by which we mean competition for voters' support between more than two parties, opening up the possibility that no one party wins a majority of votes cast. Multiparty competition is much more common than is sometimes supposed. In the European Parliament elections of June 2009, for example, 25 different political parties competed for the support of voters in the United Kingdom -a country sometimes casually thought of as having a two or two-and-a-half party system. Eleven of these parties secured the election of at least one publi...

Party Policy Diffusion

“…Roemer (2001) shows that if the issue space has more than one dimension, there are generally no equilibria if parties are pure office seekers. Under these assumptions, Laver and Sergenti (2012) also demonstrate that it is impossible to derive analytic expressions for the best strategy a party can adopt given the locations of other parties.…”

“…One such heuristic is for a party encountering electoral losses to do a volte-face, but not directly back along its past trajectory (Laver and Sergenti 2012). 5 Another heuristic is to adopt the best position you can, given where other parties are located, assuming they will not react to your change in strategy, i.e., to act in a parametrically rational way in what is actually a strategic context (Plümper and Martin 2008).…”

“…Heuristics can be conceived of as competing with one another in an evolutionary environment (Fowler and Laver 2008;Laver and Sergenti 2012), where the use of successful heuristics spreads through "replicator dynamics" (Weibull 1995). At the transnational level, learning from or emulating foreign incumbent parties of the same ideological bloc may not be "ecologically rational" (Gigerenzer and Gaissmaier 2011) in a population of heuristics where there is widespread learning or emulating from foreign incumbents.…”

Political Spaces, Dimensionality Decline and Party Competition

“…Mathematical approaches to rational choice theories, although elegant, are inadequate to explain some complex phenomena in dynamic settings when agents adapt and interact with each other [34]. Rather, they build upon unrealistic assumptions concerning the behavior of agents engaged in political competition, particularly as to the assumption of perfect rationality of voters and political parties.…”

“…Rather, they build upon unrealistic assumptions concerning the behavior of agents engaged in political competition, particularly as to the assumption of perfect rationality of voters and political parties. A realistic model of multiparty competition should consider that politics is dynamic (i.e., it does not reach a static equilibrium, but instead evolves over time), complex (i.e., outcomes at some point of time constitute subsequent inputs to the political system), diverse (i.e., politicians use different strategies or courses of action), and not random (i.e., system-level predictions can be made) (see [34], p. 3). Agent-based modeling (ABM) investigates outcomes from interactions among a diverse and large number of boundedly rational agents that adapt in an evolving system.…”