Nonexcludable

Nonexcludable is a term used in economics to describe a situation in which it is difficult or cost-prohibitive to prevent individuals from using a good or resource once it is provided. When a good is nonexcludable, providers cannot easily charge non-payers, so entry or consumption cannot be restricted effectively. Excludability is a separate concept from rivalry: a good can be nonexcludable and nonrival (a public good) or nonexcludable and rival (a common-pool resource).

The nonexcludable nature of a good often leads to the free-rider problem, where individuals have an incentive to rely on others to pay for the good. In market settings, this can result in underprovision or underfunding of such goods. To address this, governments or communities may organize provision through taxation, regulation, or collective action. In some cases, excludability can be introduced artificially (for example, with tolls or licenses), transforming the good into an excludable one and altering how it is financed and managed.

Common examples of nonexcludable goods include national defense, street lighting, public parks, and clean air in large regions. Natural entities like many fisheries or groundwater basins can also be nonexcludable and rival, classifying them as common-pool resources. Understanding nonexcludability helps explain why certain goods are typically provided or regulated by public authorities rather than left to private markets.