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Encyclopedia > Duverger's Law

Duverger's Law is a principle which asserts that a first-past-the-post election system or in other words, a Single-member, Simple-plurality 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 and recorded it in several papers published in the 1950s and 1960s. In the course of further research, other political scientists began calling the effect a “law”. For law within legal systems see law. ... The first-past-the-post electoral system is a voting system for single-member districts, variously called first-past-the-post (FPTP or FPP), winner-take-all, plurality voting, or relative majority. ... A two-party system is a type of party system where only two political parties have a realistic chance of winning an election. ... Maurice Duverger (born June 5, 1917) is a French jurist. ... // Events and trends The 1950s in Western society was marked with a sharp rise in the economy for the first time in almost 30 years and return to the 1920s-type consumer society built on credit and boom-times, as well as the the baby boom from returning GIs who... The 1960s in its most obvious sense refers to the decade between 1960 and 1969, but the expression has taken on a wider meaning over the past twenty years. ... See also: Political Science Notable political scientists Kenneth Arrow - Nobel Memorial Prize winning economist who published influential paper on his widely cited Arrows Impossibility Theorem Robert Axelrod Duncan Black - Responsible for unearthing the work of many early political scientists, including Charles Dodgson Jean-Charles de Borda - 18th century mathematician...

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How and why it occurs

Two-party systems often develop spontaneously when the voting system used for elections discriminates against third or smaller parties, because the number of votes received for a party in a whole country is not directly related to the proportion of seats it receives in the country's assembly/assemblies. While there is sometimes a coincidental relationship between votes cast and seats received in these systems, voters are not assured that their one vote will directly count toward an additional seat. The most widely-used system to have this effect, the simple plurality system (first past the post) often appears to pull systems into encouraging the survival of only two major parties: a third force can break in on the scene (the Labour Party in 20th-century Britain, or the Republican Party in the 19th-century United States, for example) but only at the ultimate expense of a former major party (the Liberal Party in Britain, the Whigs in the USA respectively). The overall system re-stabilizes into two-party mode after a three-party interlude. A voting system is a process that allows a group of people to express their tolerances or preferences about a number of options, and then selects one or more of those options, typically in a way meant to satisfy many of the voters. ... In any two-party system of politics, a third party is a party other than the two dominant ones. ... Look up Country in Wiktionary, the free dictionary In political geography and international politics a country is a geographical territory. ... Assembly may refer to the following things: In politics, any body meeting together to discuss matters, a parliament or a legislative assembly such as the French revolutionary Legislative Assembly, or a body more designed to mediate between otherwise independent bodies, such as the United Nations General Assembly. ... A plurality (or relative majority) is the largest share of something, which may or may not be a majority. ... The first-past-the-post electoral system is a voting system for single-member districts, variously called first-past-the-post (FPTP or FPP), winner-take-all, plurality voting, or relative majority. ... The Labour Party is the principal centre-left political party in the United Kingdom (see British politics). ... The Republican Party, often called the GOP (for Grand Old Party), is a political party and is one of the two major political parties in the United States (the other being the Democratic Party). ... The Liberal Party was one of the two major British political parties from the early 19th century until the 1920s, and a third party of varying strength and importance up to 1988, when it merged with the Social Democratic Party to form a new party which would become known as... Whig Party banner from 1848 with candidates Zachary Taylor and Millard Fillmore. ...


Some representation systems - such as those involving a single elected president or a mayor dominating the government - may encourage two-party systems, since ultimately the contest will pit the two most popular candidates against each other.


When constituencies (districts) vote for candidates on the basis of a geographical constituency, all votes for candidates other than the winner count for nothing. This reflects another factor that encourages a two party system: smaller parties often cannot win enough votes in a constituency because they have smaller support and sometimes more scattered support than larger parties. Often a first-past-the-post electoral system and the election of candidates from geographical constituencies (districts) appear together in a single political system: this means that some smaller parties can garner a significant proportional of votes nationally, but receive few constituency seats and thus cannot realistically expect to compete overall on an equal footing with larger country-wide parties. A constituency is any cohesive corporate unit or body bound by shared structures, goals or loyalty. ... Districts are a form of local government in several countries. ...


In countries that use proportional representation (PR), especially where the whole country forms a single constituency (like Israel), the electoral rules discourage a two-party system; the number of votes received for a party relates directly and proportionally to the number of representative seats won, and new parties can thus develop an immediate electoral niche. Duverger identified that the use of proportional representation would make a two party system less likely. However, other systems do not guarantee new parties access to the system: Malta provides an example of a stable two-party system using the single transferable vote. Proportional representation (PR) is an election system which ensures a proportionally representative result of a democratic election, x% of votes should be represented by x% in the democratic institutions, parliament or congress. ... Maurice Duverger (born June 5, 1917) is a French jurist. ... This STV ballot for the Australian Senate illustrates group voting tickets. ...


Often, two-party systems result from various factors, mostly the use of a first-past-the-post voting system, rather than from deliberate electoral/political engineering.


Counterexamples

While there are indeed many FPTP systems with two parties, there are significant counterexamples: Scotland has had until recently first-past-the-post and similar systems but has seen the development of several significant competing political parties. Many commentators regard the United Kingdom's Liberal Democrat party, since the 2005 General Election, as forming a 'third party' and creating a three-party system. The New Democratic Party in Canada has had a constant presence in Parliament since its founding in 1961. India has multiple regional parties. Duverger himself did not regard his principle as absolute: instead he suggested that first-past-the-post would act to delay the emergence of a new political force, and would accelerate the elimination of a weakening force - proportional representation would have the opposite effect. In logic, and especially in its applications to mathematics and philosophy, a counterexample is an exception to a proposed general rule, i. ... Scotland - Wikipedia, the free encyclopedia /**/ @import /skins-1. ... The Liberal Democrats, often shortened to Lib Dems, are a liberal political party based in the United Kingdom. ... A general election is an election in which all members of a given political body are up for election. ... The New Democratic Party (French: Nouveau Parti démocratique) is a left wing political party in Canada that advocates varying forms of social democracy and democratic socialism. ... 1961 (MCMLXI) was a common year starting on Sunday (link will take you to calendar). ... Proportional representation (PR) is an election system which ensures a proportionally representative result of a democratic election, x% of votes should be represented by x% in the democratic institutions, parliament or congress. ...


Additionally, William H. Riker noted that strong regional parties can distort matters, leading to more than two parties nationwide, even if there are only two parties competitive in any single district. He pointed to Canada's regional politics, as well as the U.S. presidential election of 1860, as examples of often temporary regional instability that occurs from time-to-time in otherwise stable two-party systems (Riker, 1982). William Harrison Riker (September 22, 1920 - June 26, 1993) was an influential political scientist, who advanced the field of political science through his application of game theory and mathematics to the field. ... Presidential electoral votes by state. ...


Converse does not apply

The converse of Duverger's Law doesn't necessarily follow, as other systems may also lead to stable two-party political systems. This is particularly true in the case of countries using systems that, while they are not strictly speaking "first past the post", do not incorporate proportional representation. For instance, Malta has a single transferable vote system and what seems to be stable two-party politics. Australia uses single transferable vote as well and, though not strictly a two-party system, is dominated by a major party (the Labor Party) and a major coalition (the Liberal/National coalition). Having preferential voting federally has encouraged it to spread into all the states, and to upper houses where STV gives minor parties a real chance of winning. Proportional representation (PR) is an election system which ensures a proportionally representative result of a democratic election, x% of votes should be represented by x% in the democratic institutions, parliament or congress. ... This STV ballot for the Australian Senate illustrates group voting tickets. ... The Australian Labor Party or ALP is Australias oldest political party. ... The Liberal Party of Australia is an Australian liberal conservative political party. ... The National Party of Australia is an Australian political party. ...


While some would argue that a two-party outcome is not necessarily harmful (see Two-party system), researchers and mathematicians have devoted considerable time to developing voting systems that do not appear to be subject to Duverger's Law. A two-party system is a type of party system where only two political parties have a realistic chance of winning an election. ... A voting system is a process that allows a group of people to express their tolerances or preferences about a number of options, and then selects one or more of those options, typically in a way meant to satisfy many of the voters. ...


Some systems are even more likely to lead to a two-party outcome: for example elections in Gibraltar use a partial block vote system in a single constituency, meaning that the third most popular party is unlikely to win any seats. Elections in Gibraltar gives information on election and election results in Gibraltar. ... Bloc voting (or block voting) (also called Plurality-at-large) refers to a class of voting systems which can be used to elect several representatives from a single constituency. ...


Spoiler effect

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 candidates. The common desire among voters (including a third-party candidate oneself) to avoid this problem frequently leads to the distortion of tactical voting, in which a race can be won by a candidate who is not comparatively (and proportionally) the most popular. The spoiler effect is a term to describe the effect a candidate can have on a close election, in which their candidacy results in the election being won by a candidate dissimilar to them, rather than a candidate similar to them. ... In voting systems, tactical voting (or strategic voting) occurs when a voter misrepresents his or her sincere preferences in order to gain a more favorable outcome. ...


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.)

Maurice Duverger (born June 5, 1917) is a French jurist. ... William Harrison Riker (September 22, 1920 - June 26, 1993) was an influential political scientist, who advanced the field of political science through his application of game theory and mathematics to the field. ...

See also

  • List of democracy and elections-related topics

  Results from FactBites:
 
Duverger's law (163 words)
Duverger's Law is a principle which asserts that a first-past-the-post voting system naturally leads to a two-party system.
It eventually became referred to as a "law" in works by other political scientists, who applied further research to the proposition, and devised alternative voting systems which do not appear to be subject to the same characteristics as first-past-the-post.
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.
Duverger's law - Wikipedia, the free encyclopedia (904 words)
Duverger's Law is a principle which asserts that a first-past-the-post election system or in other words, a Single-member, Simple-plurality system, naturally leads to a two-party system.
Duverger himself did not regard his principle as absolute: instead he suggested that first-past-the-post would act to delay the emergence of a new political force, and would accelerate the elimination of a weakening force - proportional representation would have the opposite effect.
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 candidates.
  More results at FactBites »

 
 

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