Duverger's law

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Duverger's Law ( Loi de Duverger ), named after the French lawyer and political scientist Maurice Duverger , is the presumed legality according to which a relative majority voting system leads to the formation of a two-party system . Conversely, a proportional representation system leads to a large number of parties .

The idea behind these assumptions is that in a single- constituency relative majority voting system, few candidates have a realistic chance of being elected. A rational voter then votes not to the candidate of the party he personally prefers, but to another candidate who has a better chance of success. The votes are concentrated on two parties, one on the right and one on the left. This effect was formulated by Duverger in several essays in the 1950s and 1960s and then generally adopted as Duverger's law in the specialist literature.

However, the law has now been widely criticized. The effect only comes about when there are few lines of conflict in society, typically those between rich and poor (labor and capital). That would benefit a social democratic party on the one hand and a conservative - liberal party on the other. In most societies, however, there are also other lines of conflict, for example confessional, ideological or cultural. It is also important whether minorities live concentrated in individual regions (and consequently can conquer constituencies) or scattered across the country.

The classic example of Duverger's law was Great Britain ; In 1974 and 2010, however, the Liberal Party and the Liberal Democrats, as the third party, succeeded in gaining a majority-critical number of seats in parliament. The government coalition between the Conservative Party and the Liberal Democrats in the years 2010 to 2015 can serve as a counterexample for the assumed legality. India also elects according to single constituencies, where a large number of small regional parties come to parliament. In the USA, on the other hand, the law has been confirmed, supported among other things by intensive gerrymandering .

Individual evidence

  1. ^ Maurice Duverger: Party Politics and Pressurce Groups. A comparative introduction. Crowell, New York 1972, pp. 27-29.