Principles and design
The proportionality of PR depends on district magnitude, the number of members elected per district, the allocation formula and the legal threshold. Taagepera and Shugart (1989) systematized how larger magnitudes make it easier for small parties to win seats. Lijphart (1994) compared 27 democracies and showed that outcomes vary greatly with design even within PR. This contrasts with Duverger's law, which links single-member plurality to two-party systems.
Measurement and effects
Laakso and Taagepera (1979) proposed the effective number of parties, and Gallagher (1991) proposed an index of disproportionality between vote and seat shares. By these measures PR countries generally have more effective parties and lower disproportionality. Blais and Carty (1990) reported somewhat higher turnout under PR. Lijphart saw such institutions as a core element of consensus democracy.
Origins and assessments
Boix (1999) argued that as workers' parties grew in the early twentieth century, established right-wing parties adopted PR fearing collapse under majoritarian rules. This connects to party formation in cleavage theory. PR is praised for representativeness but criticized because more parties can mean long coalition negotiations and blurred accountability.
FAQ
- What is proportional representation in simple terms?
- A system that gives parties seats in proportion to their votes. A party with 30% of the vote gets roughly 30% of the seats.
- Why is PR linked to multiparty systems?
- Small parties can win seats in line with their votes, so voters do not feel their votes are wasted and more parties survive.
Sources reviewed: 2026-10-26
References
- Rae, D. W. (1967). The political consequences of electoral laws. Yale University Press. The first quantitative comparison of electoral laws.
- Taagepera, R., & Shugart, M. S. (1989). Seats and votes: The effects and determinants of electoral systems. Yale University Press. District magnitude and seat allocation.
- Lijphart, A. (1994). Electoral systems and party systems: A study of twenty-seven democracies, 1945–1990. Oxford University Press. Comparing 27 democracies.
- Laakso, M., & Taagepera, R. (1979). "Effective" number of parties: A measure with application to West Europe. Comparative Political Studies, 12(1), 3–27. The effective number of parties.
- Gallagher, M. (1991). Proportionality, disproportionality and electoral systems. Electoral Studies, 10(1), 33–51. The Gallagher disproportionality index.
- Boix, C. (1999). Setting the rules of the game: The choice of electoral systems in advanced democracies. American Political Science Review, 93(3), 609–624. Why countries adopted PR.
- Blais, A., & Carty, R. K. (1990). Does proportional representation foster voter turnout? European Journal of Political Research, 18(2), 167–181. PR and turnout.