Coase Theorem

The proposition and its starting point

In "The Federal Communications Commission" (1959) and "The Problem of Social Cost" (1960), Ronald Coase overturned the prevailing view of externalities. The Pigouvian tradition (1920) on market failure held that the party causing harm, such as a polluter, should be taxed or held liable. Coase pointed out that externalities are reciprocal: if a rancher's cattle damage a neighboring farmer's crops, restricting the cattle harms the rancher and allowing them harms the farmer. He argued that with zero transaction costs and clear property rights, whether the farmer is given a right to protection or the rancher a right to graze, the two will bargain to the outcome that maximizes total value. The allocation of rights affects the distribution of wealth, not the efficiency of resource allocation. George Stigler (1966) named this the "Coase theorem."

The real message: transaction costs

Coase himself stressed that a world of zero transaction costs is a starting point, not reality. Because finding partners, gathering information, and writing and enforcing contracts are costly, who holds rights and which institutions exist shape outcomes. This links to "The Nature of the Firm" (1937), which explained why firms exist in terms of transaction costs, and laid foundations for transaction cost economics and the new institutional economics. Calabresi and Melamed (1972) extended it into a law-and-economics framework distinguishing "property rules" such as injunctions from "liability rules" such as damages. Steven Cheung (1973) showed that beekeepers and orchard owners actually sign pollination contracts, undercutting the textbook use of bees as a public-goods-style market failure.

Tests and limits

In experiments by Hoffman and Spitzer (1982), small-group bargaining usually reached efficient agreements. Kahneman, Knetsch and Thaler (1990), however, showed that the endowment effect, valuing what one owns more highly, means initial allocations can affect trading outcomes. Farrell (1987) noted that under information asymmetry, when parties do not know each other's costs and values, bargaining may break down or be inefficient, and game theory shows that with many parties, as with air pollution, free riding makes bargaining itself difficult. Ellickson (1991) found that ranchers' neighbors in California settle disputes through social norms rather than law, complementing the theorem's assumptions from another angle. Reviewing sixty years of debate, Medema (2020) concluded the theorem is most valuable as a starting point for institutional analysis rather than as a conclusion.

FAQ

Does the Coase theorem mean government regulation is unnecessary?

No. In a world of high transaction costs, rights allocation and legal institutions shape outcomes, so the lesson is closer to comparing which institutions reduce transaction costs and raise total value.

Why is it called a theorem?

Coase did not present it as a mathematical theorem; George Stigler (1966) summarized his argument as a single proposition in a textbook and gave it the name, which then spread.

Sources reviewed: 2026-10-26

References

1. Coase, R. H. (1937). The nature of the firm. Economica, 4(16), 386–405.
2. Coase, R. H. (1959). The Federal Communications Commission. Journal of Law and Economics, 2, 1–40.
3. Coase, R. H. (1960). The problem of social cost. Journal of Law and Economics, 3, 1–44.
4. Pigou, A. C. (1920). The Economics of Welfare. London: Macmillan.
5. Stigler, G. J. (1966). The Theory of Price (3rd ed.). New York: Macmillan.
6. Calabresi, G., & Melamed, A. D. (1972). Property rules, liability rules, and inalienability: One view of the cathedral. Harvard Law Review, 85(6), 1089–1128.
7. Cheung, S. N. S. (1973). The fable of the bees: An economic investigation. Journal of Law and Economics, 16(1), 11–33.
8. Hoffman, E., & Spitzer, M. L. (1982). The Coase theorem: Some experimental tests. Journal of Law and Economics, 25(1), 73–98.
9. Farrell, J. (1987). Information and the Coase theorem. Journal of Economic Perspectives, 1(2), 113–129.
10. Kahneman, D., Knetsch, J. L., & Thaler, R. H. (1990). Experimental tests of the endowment effect and the Coase theorem. Journal of Political Economy, 98(6), 1325–1348.
11. Ellickson, R. C. (1991). Order without Law: How Neighbors Settle Disputes. Cambridge, MA: Harvard University Press.
12. Medema, S. G. (2020). The Coase theorem at sixty. Journal of Economic Literature, 58(4), 1045–1128.