---
title: "Duverger's Law — Definition & Meaning | Model Diplomat"
description: "Duverger's Law states that single-member-district plurality systems create two-party competition, a key concept for political scientists and exam candidates."
url: "https://modeldiplomat.com/learn/glossary/duverger-s-law"
---

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Model Diplomat Research Team · Last reviewed June 22, 2026

TL;DR

- Duverger's Law holds that single-member-district plurality electoral systems tend to produce and sustain two-party competition, while proportional representation favours multipartism.
- What is the difference between the mechanical and psychological effects in Duverger's Law?
- Why is India considered a counterexample to Duverger's Law?
- What did Duverger say about proportional representation?
- How did Riker and Cox refine Duverger's Law?

[Civil Service & Diplomatic Exams](https://modeldiplomat.com/learn/civil-services/glossary)Updated June 22, 2026

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Example

In the 1992 US presidential election, Ross Perot won 18.9% of the popular vote but zero Electoral College votes, illustrating the mechanical effect of single-member plurality that Duverger's Law predicts.

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