Duverger's law

Duverger's Law is a principle which asserts that a first-past-the-post election system naturally leads to a two-party system.

The discovery of this principle is attributed to Maurice Duverger, a French sociologist who observed the effect in several papers published in the 1950s and 1960s. In the course of further research, other political scientists began calling the effect a “law.” Some researchers and mathematicians have devised alternative voting systems that do not appear to be subject to the supposed drawbacks of first-past-the-post, though many would argue that a two-party system is actually desirable.

A frequent consequence of Duverger's law is the spoiler effect, where a third-party candidate takes votes away from one of the two leading candiates.

External links

• Maurice Duverger, "Factors in a Two-Party and Multiparty System," in Party Politics and Pressure Groups (New York: Thomas Y. Crowell, 1972), pp. 23-32.
• William H. Riker, The Two-party System and Duverger's Law: An Essay on the History of Political Science American Political Science Review, 76 (December, 1982), pp. 753-766. (This link is only accessible to individuals with access to JSTOR through a university, a corporation or another organization.)