rivalrous

Rivalrous describes a characteristic of goods and resources in which one person's use reduces the amount available for others. In economics, a good is rivalrous if consumption by one individual diminishes the quantity that remains for others. Rivalrousness is usually discussed alongside excludability to classify goods into four categories: private goods (rivalrous and excludable), common-pool resources (rivalrous and non-excludable), club goods (non-rivalrous and excludable) and public goods (non-rivalrous and non-excludable).

Examples help illustrate the concept: food or clothing are rivalrous and excludable; fish stocks in an open-access fishery are rivalrous and non-excludable; paid clubs or streaming services are typically excludable and non-rivalrous; public goods like national defense or basic scientific knowledge are non-rivalrous and non-excludable. The degree of rivalry can vary with congestion and technology; some goods are non-rivalrous at low levels of use but become rivalrous as usage increases.

Rivalrousness has implications for allocation and pricing. Prices and property rights can help ration scarce resources and prevent depletion, particularly for common-pool resources where overuse is a problem. In policy, recognizing rivalry informs welfare analysis, cost-benefit assessment, and regulatory design for resource management.