The Evolution of Party Systems between Elections

Abstract

T he existing political science account of party competition pays little attention to the evolution of legislatures between elections, despite the fact that, in all real legislatures, there is a great deal of politics between elections. In particular, legislators may defect from one party and join another, parties may split and fuse, and the party system may thereby evolve into one quite different from that produced by the election result. This carries obvious analytical implications for modeling party competition and important normative implications for our appreciation of representative democracy. In supplying the link between the popular mandate and public policy in representative democracy, the forces that shape legislatures between elections are clearly very important.While there is a literature on party switching in the U.S. Congress (e.g., Nokken 2000), exploration of this in other contexts is very limited. Yet it is precisely in multiparty systems that the phenomenon is most prevalent and important. In the Italian legislature between 1996 and spring 2000, for instance, more than one in four deputies changed parties at least once (Heller and Mershon 2001, 2). Similar patterns of party switching can be seen in Japan (Laver and Kato, 2001) (Ágh 1999;Verzichelli 1999). Every defection from some party, however, implies that some other party is willing to accept the defector. Existing work on party switching focuses exclusively on the rationale of the switchers, while ignoring the incentives of the parties that the switchers are attempting to join. Finally, existing models have nothing to say as to which party switchers will wish to join when there are several possibilities.Absent from the literature on party switching is any consideration of the payoffs that politicians expect from affiliation to a given legislative party. Yet, in addition to the electoral benefits of a party label, membership of a legislative party is the key to many of the payoffs of "winning" the political game by getting into office and being associated with the incumbent government, as Cox (1987) pointed out in his analysis of the evolution of coherent political parties in Britain. Even in countries such as Britain or Ireland where the electoral system makes it possible to be returned to parliament as an "independent" without party affiliation, it is effectively impossible for an independent legislator to enter government.Here we model the party affiliation of legislators as a matter of choice that is continuously under review. We explore ways in which some parties attract potential defectors, some are willing to accept defectors, and some are both attractive and willing, allowing defections actually to take place. Rather than seeing the legislative party system as remaining static between elections, we treat the composition of legislative parties as the output of one cycle in the process of legislative politics, as well as an input into the next cycle. In this way, we explore the evolution of legislative party systems between election...

Theories of coalition formation: An empirical test using data from Danish local government

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Bonding in Pursuit of Policy Goals: How MPs Choose Political Parties in the Legislative State of Nature

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