Thursday, November 1, 2012

Blog 7: Duverger's Law

                According to Duverger’s law there is a correlation between an electoral district’s effective number of parties and its electoral rules. This law would predict that a country would either have two parties and single member district plurality rules, or more than two parties and proportional rules.¹ The study of the United Kingdom reaffirms this law.
                The United Kingdom’s electoral system in the House of Commons is run on a system of single member district plurality (SMDP).² This means that the country is geographically separated into districts of relatively equal population. Each district is represented by a single official who is elected based off of the plurality rule (the winning candidate is the one who just receives the most votes, not necessarily a majority).³ District magnitude denotes the number of legislative seats allotted to each district within a legislative system.⁴ The district magnitude of the House of Commons in the United Kingdom is one; there is only one official, or one legislative seat, per district, hence the single member district part of SMDP. The allocation of seats from the popular vote is governed by the formula of plurality. This means that whoever wins the most votes will win the seat. It is a winner-takes-all system. Another aspect of an electoral system is the list structure. An open, or preferential, list means the voters choose the order in which candidates of a party are elected, contrasting a closed list where other officials choose this order.⁵ The United Kingdom has an open list structure, in that voters can vote for the specific candidate they want to hold the legislative seat. There is no threshold in the United Kingdom, meaning that the political parties do not have to get a minimum percentage of votes for those votes to count or for that party to maintain its party registration. Any party can have candidates run for office no matter its size. The United Kingdom’s electoral rules tend to favor larger parties, making Duverger’s law very plausible.
In looking at the last legislative election in the House of Commons in 2010, the Conservative Party received 36% of the votes, but got 47% of the seats. The Labour Party had 29% of the vote and received 40% of the seats. However, the Liberal Democrats closely followed with 23% of the votes and only received 9% of the seats.⁶ Just this shows that the United Kingdom has two main parties, but it can be seen mathematically as well. With a formula using the percentage of legislative seats held by every party, it is found that the country has 2.57 effective parties. This means that there are two main parties, but there are several others that very marginally affect the country’s politics.
The two effective parties of the United Kingdom are arguably a result of its SMDP system. Because the seats are allocated based on plurality rules, larger parties are favored and two main parties emerge. The Conservative Party and the Labour Party clearly dominate politics in the United Kingdom. Because of these SMDP rules, the percentage of votes for small parties translates into a smaller percentage of seats, whereas the opposite occurs for the two larger parties, thus giving those two parties a considerable amount of political power.
The study of the United Kingdom supports the claim of Duverger’s law. As it predicts, this country has single member district plurality and also has two effective political parties.
                 

¹”Duverger’s Law.” Wikipedia. http://en.wikipedia.org/wiki/Duverger's_law
²“United Kingdom House of Commons: Electoral System.” Inter-Parliamentary Union. http://www.ipu.org/parline-     e/reports/2335_B.htm
³ “Single Member Districts.” Fair Vote: Program for Representative Government. http://archive.fairvote.org/?page=765
District Magnitude and Political Parties.” Ace: The Electoral Knowledge Network. http://aceproject.org/ace-en/topics/pc/pcc/pcc04/pcc04a
“Open list.” Wikipedia. http://en.wikipedia.org/wiki/Open_list
“Elections 2010.” BBC. http://news.bbc.co.uk/2/shared/election2010/results/


3 comments:

  1. Your blog is, first off, very easy to read and well written. It presented the information in a clear, detailed manner without going into too much of the nitty gritty. It's very interesting that in the United Kingdom has two effective parties but other parties still receive what seem to be large percentages of the vote.

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  2. I agree with Caroline. I don't know if its very fair that one party receives 23% of the vote yet only 9% of the seats. A little unjust for those who voted for that party in my opinion.

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