Proportional representation

Proportional representation
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Name	Proportional representation
Type	Electoral system
Introduced	19th century
Regions	Worldwide

Proportional representation is a class of electoral arrangements designed to allocate legislative seats roughly in proportion to votes cast for parties, lists, or candidates. It contrasts with majoritarian systems used in countries such as United Kingdom, United States, Canada, Australia, and India. Advocates and critics from institutions such as European Parliament, United Nations, Council of Europe, African Union, and Organization for Security and Co-operation in Europe debate its effects on party systems, coalition formation, and representation of minorities.

Overview

Proportional representation systems aim to translate vote shares into seat shares using mechanisms adopted in jurisdictions like Germany, Netherlands, Sweden, Spain, and Portugal. Variants include party-list systems prominent in Brazil, Argentina, Chile, South Africa, and Israel as well as mixed systems used in New Zealand, Japan, Italy, Mexico, and Hungary. Designers draw on political theory from figures such as John Stuart Mill, Thomas Hare, Arend Lijphart, Maurice Duverger, Giuseppe Mazzini, and Karl Marx to justify proportional outcomes in plural societies like Belgium, Switzerland, Austria, and Norway.

Electoral systems and methods

Common mathematical methods include the D'Hondt method associated with reforms in Belgium and Spain, the Sainte-Laguë method used in Sweden and New Zealand, and the Hare quota connected to the single transferable vote in Ireland and Malta. List systems may be closed lists as in Portugal and South Korea or open lists as in Brazil and Finland, while mixed-member proportional systems combine single-member districts like those in United Kingdom or Canada with compensatory seats as in Germany and Scotland. Thresholds and district magnitude choices echo debates in commissions such as those convened in France, Italy, Greece, and Denmark.

Implementation and variations by country

National implementations vary: Germany uses mixed-member proportional design with overhang and leveling seats, Netherlands employs a single national constituency with open lists, Israel applies a single nationwide list with a statutory threshold, and Switzerland features cantonal list adaptations. Emerging democracies such as Tunisia, Nepal, Kenya, and South Africa have adopted proportional elements during transitions, while countries like Japan and Italy have shifted between majoritarian and proportional features across reforms involving actors like Shinzo Abe, Silvio Berlusconi, Matteo Renzi, and Yoshihide Suga.

Political effects and criticisms

Scholars and practitioners including Arend Lijphart, Maurice Duverger, Giovanni Sartori, Juan Linz, Robert Dahl, and Samuel Huntington analyze effects such as party fragmentation observable in Israel, coalition governance typical in Belgium and Netherlands, and minority representation improvements noted in New Zealand and South Africa. Critics point to instability in cases like Italy and alleged accountability diffusion cited by commentators referencing Tony Blair, Margaret Thatcher, Barack Obama, Vladimir Putin, and Recep Tayyip Erdoğan. Discussions involve interest groups and movements such as Green Party (Europe), UK Independence Party, Five Star Movement, Sinn Féin, and Ennahda.

Historical development

Early advocates include Thomas Hare and reformers in the 19th century such as John Stuart Mill and associations in United Kingdom and France; adoption accelerated with democratization waves after World War I, World War II, and decolonization movements in India, Africa, and Latin America. Postwar institutional design in Germany and constitutional debates in Italy and Japan shaped modern proportional formulas, while European integration processes through institutions like the Council of Europe and European Union influenced electoral harmonization discussions involving actors such as Konrad Adenauer, Charles de Gaulle, Winston Churchill, and Franklin D. Roosevelt.

Mathematical properties and formulas

Quota and divisor methods underpin proportional allocation: Hare quota, Droop quota, and Hagenbach-Bischoff quota relate to seat allocation examples studied in mathematical works by Thomas Piketty, Kenneth Arrow, Amartya Sen, John Nash, and Donald Saari. Divisor methods include D'Hondt (Jefferson) favoring larger lists as analyzed in comparisons by Sainte-Laguë, while Sainte-Laguë (Webster) produces different rounding properties relevant to apportionment cases like those adjudicated in United States v. Booker-style debates and commissions involving Alexander Hamilton, James Madison, and Edmund Burke. Metrics such as Gallagher index, Loosemore–Hanby index, and effective number of parties (Laakso–Taagepera index) quantify disproportionality and have been applied in studies by Arend Lijphart, Rein Taagepera, Peter Mair, and Pippa Norris.

Category:Electoral systems