What is a minimal winning coalition in simple terms?

A coalition made up only of the parties needed to pass a majority, so that losing any one party would break the majority.

Are real coalition governments always minimal winning?

No. Many are, but minority governments and oversized coalitions are common, and factors such as policy distance and institutions also matter.

Minimal Winning Coalition

🏛️ Politics & Public Administration By CampusDown Wiki Editorial Team Last updated October 27, 2026 Views 1

A minimal winning coalition is one that commands a majority but would lose it if any single member left. In 1962 William Riker proposed the size principle: rational actors form coalitions only as large as needed to win so as to share the spoils among as few as possible. It is a foundational theory of coalition government formation in parliamentary systems.

Contents

1. The size principle
2. Policy-based theories
3. Evidence and limits
4. FAQ
5. References

The size principle

Gamson (1961) argued that participants expect payoffs in proportion to the resources they contribute, so coalitions with the minimum resources needed to win will form. Riker (1962) formalized this with game theory: in zero-sum situations rational actors avoid sharing gains with unnecessary members and so form minimal winning coalitions. In parliamentary systems the prediction is that cabinets include only the parties needed to pass the majority threshold.

Policy-based theories

Axelrod (1970) argued that parties care about policy as well as office and therefore form minimal connected winning coalitions of ideologically adjacent parties. De Swaan (1973) tested the theory that coalitions minimize internal policy distance using nine European parliaments. Office-seeking and policy-seeking models thus form two strands of coalition theory.

Evidence and limits

Laver and Schofield (1990) showed that many European coalitions are minimal winning but that minority governments and surplus coalitions are also common. Laver (1998) reviewed government formation models, and Martin and Stevenson (2001) tested several theories in one model, finding that minimal winning status, ideological distance and the largest party's inclusion all matter. Veto players and institutional rules also shape coalition formation.

FAQ

What is a minimal winning coalition in simple terms?: A coalition made up only of the parties needed to pass a majority, so that losing any one party would break the majority.
Are real coalition governments always minimal winning?: No. Many are, but minority governments and oversized coalitions are common, and factors such as policy distance and institutions also matter.

Sources reviewed: 2026-10-26

References

Gamson, W. A. (1961). A theory of coalition formation. American Sociological Review, 26(3), 373–382. Early coalition theory.
Riker, W. H. (1962). The theory of political coalitions. Yale University Press. The size principle.
Axelrod, R. (1970). Conflict of interest: A theory of divergent goals with applications to politics. Markham. Minimal connected winning coalitions.
Laver, M., & Schofield, N. (1990). Multiparty government: The politics of coalition in Europe. Oxford University Press. Coalition politics in Europe.
Laver, M. (1998). Models of government formation. Annual Review of Political Science, 1, 1–25. Review of government formation models.
Martin, L. W., & Stevenson, R. T. (2001). Government formation in parliamentary democracies. American Journal of Political Science, 45(1), 33–50. Joint test of formation theories.
de Swaan, A. (1973). Coalition theories and cabinet formations: A study of formal theories of coalition formation applied to nine European parliaments after 1918. Elsevier. Policy-distance theories.

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This article was last updated on October 27, 2026. It is based on widely recognized original works and textbooks; when citing it in a paper, please check the original sources listed in the references.