Blog 7

Luke Bell

11/2/2012

Professor Hawkins

Blog Post 7: Duverger’s Law

A common complaint among contemporary American citizens is that the government of the United States is excessively polarized because of partisan conflict between Republicans and Democrats.  In his seminal work on electoral systems, Maurice Duverger makes the claim that single-member-district plurality voting systems almost always result in the existence of only two effective political parties (Duverger 1972, 22-32).  If Duverger’s assertions are true, there are significant ramifications for policy-makers and citizens alike.  In order to test the validity of Duverger’s argument about electoral systems and the effective number of political parties, I analyze the House of Commons in the United Kingdom.  

The United Kingdom’s House of Commons has a membership of 650 directly elected representatives, referred to as Members of Parliament (Inter-Parliamentary Union 2012).  Each Member of Parliament represents only one district.  The districts are rationed out to each nation within the United Kingdom; England is allotted 531 districts, Scotland, fifty-nine, Wales, forty, and Ireland, eighteen (Inter-Parliamentary Union 2012).  Elections are administered using a plurality or “first-past-the-post” rule and each district is represented by only one Member of Parliament (Inter-Parliamentary Union, 2012).  In other words, the magnitude of each district is one.  Because the United Kingdom employs a single-member-district plurality system, there are no election formulas or thresholds.  Rather, each district election is governed by a winner-take-all rule, with one candidate and party emerging victorious.  

In the most recent parliamentary election in the United Kingdom (2010), the Conservative Party received 306 seats, the Labour Party received 258 seats, the Liberal Democrats received fifty-seven seats, the Democratic Unionist Party received eight seats and a number of smaller received between one and five seats (Inter-Parliamentary Union 2012).   According to a formula for the number of collective parties, the 2010 elections in the House of Commons resulted in approximately 2.61 effective political parties.  The traditionally strong Conservative and Labour Parties received most of the seats in the House of Commons, but the up-and-coming Liberal Democrats also received a relatively significant nine percent of parliamentary seats (Inter-Parliamentary Union 2012).  While nine percent may not seem like a substantial seat share, the Liberal Democrats won enough seats to become a force to be reckoned with in the formation of parliamentary coalitions.  

According to Duverger’s Law, a single-member-district plurality system should produce only two effective political parties.  Because the 2010 United Kingdom elections resulted in closer to three effective parties, it seems that Duverger’s Law does not always accurately predict partisan outcomes in SMDP systems.  While the 2010 election results seem to contradict Duverger’s Law, a brief analysis of British political history casts additional light on the subject.  The Liberal Democratic Party was formed in 1988 and began to win seats in British elections in 1992 (Moskowitz and Kinross 2010).  Prior to the formation of the Liberal Democratic Party, the British system had been dominated by the Conservative and Labour Parties.  Indeed, from 1945 to 1988, the United Kingdom political scene was characterized by polarized two-party government (Moskowitz and Kinross 2010). From 1890 to 1945, however, the House of Commons was divided among three and sometimes four parties, with minority groups like the Liberal, Irish National, and Sinn Fein Parties each commanding a respectable vote share, though usually not simultaneously (Moskowitz and Kinross 2010).  The strong presence of at least three parties within the single-member-district plurality House of Commons during the 1890-1945 era suggests that the multi-party elections from 1988-2010 are not an anomaly.  Because of the strong performance of three political parties in the United Kingdom in the 2010 elections and during other periods in the twentieth century, I argue that Duverger’s Law does not consistently predict the partisan outcomes produced by SMDP systems.  

REFERENCES

Duverger, Maurice. 1972. Party politics and pressure groups. New York: Crowell.  

Inter-Parliamentary Union. 2012a. United Kingdom House of Commons: Electoral system. http://www .ipu.org /parline-e/reports/2335_B.htm (accessed November 1, 2012).  

Inter-Parliamentary Union. 2012b. United Kingdom House of Commons: Last elections. http://www.ipu .org/parline-e/reports/2335_E.htm (accessed November 1, 2012).  

Moskowitz, Gary, and David Kinross. 2010. History of the House of Commons. Telegraph. http://www.telegraph.co.uk/news/election-2010/7544741/History-of-the-House-of-Commons.html (accessed November 2, 2012).