Coase Theorem
Under low transaction costs, externalities can be efficiently resolved by private bargaining.
The Coase Theorem, named by George Stigler from Ronald Coase's 1960 'Problem of Social Cost', holds that under zero transaction costs and well-defined property rights, private parties can bargain to an efficient allocation of resources regardless of how property rights are initially assigned, with the initial assignment affecting only the distribution of welfare. The theorem's actual analytical contribution lies less in the zero-transaction-cost result (which Coase himself viewed as a foil) than in the corollary that with positive transaction costs, the assignment of legal rights matters substantively for efficiency, putting law and institutions at the center of economic analysis. Coase's paper effectively founded the field of law and economics and earned him the 1991 Nobel Prize, with the framework underpinning much of modern environmental policy debate, particularly emissions-trading designs.
Core components
- Zero-transaction-cost benchmark
- Well-defined property rights
- Bargaining to efficient outcome
- Invariance of efficient allocation to initial rights assignment
- Distributional effect of initial assignment
- Positive-transaction-cost case where assignment matters substantively
Primary use case
Foundation of law and economics; environmental policy debates including emissions trading vs Pigouvian taxation; tort law analysis; property law; analysis of contractual rights and remedies.
Common criticisms
- Zero-transaction-cost assumption rarely holds in practice
- multi-party bargaining is plagued by holdout, free-rider, and asymmetric-information problems that block efficient outcomes
- Coase himself emphasized the positive-transaction-cost case but the theorem is often misread as endorsing laissez-faire
- doesn't address distributional concerns even when efficiency is reached
- income effects and wealth-dependent valuations weaken invariance.
Lineage
- Siblings
- Pigouvian Taxation, Tragedy of the Commons, Transaction Cost Economics