Schilperoord / Spatial models of political competition with endogenous political parties /27

Two of the most important action selection processes analyzed in the social sciences are the choice by citizens of parties to support in elections and the choice by party leaders of policy “packages ” offered to citizens in order to attract this support. Having reviewed some of the main approaches to analyzing these choices and the reasons for doing this using the methodology of agent-based modeling, we extend a recent agent-based model of party competition to deal with the birth and death of political parties, treating the number and identity of political parties as an output of, rather than an analyst-specified input to, the process of party competition. Party birth is modeled as an endogenous change of agent type from citizen to party leader, which requires describing (cumulative) citizen dissatisfaction with the history of the system. Aggregate outputs are measured in terms the mean and standard deviation of citizens ’ distances from their closest party, and the configuration of party positions is characterized in terms of mean party eccentricity. Endogenous birth and death of parties transforms into a dynamic system even an environment where all agents have otherwise non-responsive adaptive rules. A key parameter is the survival threshold, with lower thresholds leaving citizens on average less dissatisfied. Paradoxically, the adaptive rule most successful for party leaders in winning votes makes citizens on average less happy than under other policy-selection rules in birth-adapted party systems. Draft paper prepared for