Free-rider problem

A collective-action problem in which people benefit from a public good without contributing to its provision, weakening incentives to provide it.

Public good: A good that is non-excludable and non-rivalrous, so one person’s use does not prevent others’ use. Non-excludability lets people receive the benefit without paying toward provision.
Non-excludability: A property of a good that makes it difficult or impossible to prevent non-payers from using it. It is the feature that allows non-contributors to share in the benefit.
Climate change mitigation: Actions that reduce greenhouse-gas emissions or increase their removal from the atmosphere. Countries can benefit from global emissions cuts while leaving the costs to others.
Tragedy of the commons: The depletion of a shared, rival resource when individuals act in their own interest. Unlike classic free-riding, this problem centers on overuse of a resource rather than underprovision.
Compulsory taxation: Government collection of mandatory payments to finance public purposes. Mandatory contributions can fund goods that voluntary payments would undersupply.
Collective action: Coordinated effort by multiple people to achieve a shared outcome. Free-riding is one obstacle to achieving shared outcomes through voluntary effort.
Non-rivalry: A property of a good whose use by one person does not reduce the amount available to others. It helps distinguish public goods from shared resources that users deplete.
Tax evasion: The illegal concealment or misrepresentation of income or other tax liabilities to avoid paying taxes. Tax evaders benefit from public services while withholding contributions that fund them.
Prisoner's dilemma: A strategic game in which individually rational choices can leave all participants worse off than cooperation would. Its incentives can model why participants withhold contributions to a shared good.
Selective incentives: Private rewards or penalties tied to participation in a collective effort. They give individuals reasons to contribute beyond the shared benefit.

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