Multi-party competition with exit: A comment on Duverger's Law

Abstract

Contrary to Duverger's Law, there exist multi-party systems in conjunction with simple majority single-ballot systems. At least three exceptions exist to this “law”. Rae (1971) and Riker (1976; 1982) offer explanations for two of the most prominent exceptions, i.e. Canada and India. I also discuss another exception, Great Britain. In this paper, I use a simple one-dimensional spatial model to show that a multi-party system can be supported under a simple majority single-ballot system. This explanation depends on the way political parties exit the system. If parties decide sequentially whether or not to exit, a multi-party system can not be maintained. If political parties make this decision simultaneously, a multi-party system may be able to sustain itself.