Abstract

Externalities are an important concept in economic theories of market failure, aiming to justify state regulation of the economy. This article explores the concept of externalities from a philosophical perspective. It criticizes the utilitarian nature of economic analyses of externalities, showing how they cannot take into account values like freedom and justice. It then develops the analogy between the concept of externalities and the 'harm principle' in political philosophy. It argues that the harm principle points to the need for a theory of basic interests to judge when a harm is imposed. Similarly, externality analyses should use such a theory of basic interests as the basis for judgments about legitimate state intervention. This proposal is defended against objections, and illustrated with a case study of the US Supreme Court's ruling on the Affordable Care Act, which shows how the judicial reasoning implicitly interprets externalities in terms of basic interests.