What are public goods?

• Public goods are goods/services that are non-rivalrous and non-excludable.

• Non-rivalrous = one person’s consumption does not reduce the amount available to others.

• Non-excludable = people cannot easily be prevented from benefiting, even if they do not pay.

• Classic examples: street lighting, national defence, flood control, lighthouses.

• Because of these two characteristics, the price mechanism works poorly, so markets may fail to provide the socially desirable quantity.

• Exam phrase: public goods create market failure because the market leads to underprovision and therefore allocative inefficiency.

Why public goods cause market failure

• Private firms are usually motivated by profit.

• With a public good, many consumers can enjoy the benefit without paying.

• This means firms cannot collect enough revenue, so they have little incentive to produce the good at all, or they produce too little.

• Therefore, the market outcome is underprovision of the public good.

• This creates allocative inefficiency because society’s welfare would be higher if more of the public good were provided.

• Exam link: the marginal social benefit of a public good is often greater than the benefit captured by a private producer, so the market quantity is below the socially optimal quantity.

The free rider problem

• The free rider problem occurs when people can receive the benefits of a good without paying for it.

• Since consumers expect others to pay, they have an incentive to free ride.

• If many people act this way, the good may be not provided at all or provided in insufficient quantity.

• The free rider problem is the core reason why private markets fail with public goods.

• Exam chain: non-excludability → free rider problem → underpayment → underprovision → allocative inefficiency.

• Strong real-world examples: people benefiting from streetlights or national defence whether or not they contribute directly.

Government intervention in response to public goods

• The syllabus requires two responses: direct provision and contracting out to the private sector.

• Direct provision = the government finances and provides the good itself, usually using tax revenue.

• This overcomes the free rider problem because funding is compulsory through taxation, not voluntary.

• Examples: street lighting, national defence, public flood barriers.

• Contracting out = the government pays a private firm to provide the public good on its behalf.

• This can combine public financing with private sector production expertise.

• In both cases, the aim is to increase provision toward the socially desirable level.

Evaluation of government intervention

• Advantage of direct provision: ensures the good is provided even when it is unprofitable for private firms.

• Advantage of contracting out: may improve efficiency, specialisation, and cost control if private firms are more productive.

• Possible limitation of direct provision: risk of government failure, bureaucracy, or inefficiency.

• Possible limitation of contracting out: private contractors may cut quality, pursue profit, or require strong monitoring.

• The most effective policy depends on the nature of the good, costs, monitoring, and government capacity.

• In evaluation, always refer to stakeholders: taxpayers, consumers/citizens, private firms, and the government.

Exam-useful chains and phrases

• Public good = non-rivalrous + non-excludable.

• Because the good is non-excludable, consumers can free ride.

• Because consumers can free ride, firms cannot charge all beneficiaries.

• Therefore, the market underprovides the good.

• This results in market failure and allocative inefficiency.

• Government intervention can correct this through direct provision or contracting out.

• Good concluding sentence: government financing can move output closer to the socially optimal level.

Common exam mistakes to avoid

• Do not confuse public goods with merit goods. Merit goods are underconsumed due to imperfect information/undervalued private benefit; public goods are underprovided mainly because of non-excludability and the free rider problem.

• Do not say all goods provided by government are public goods. Some government-provided goods are not truly non-rivalrous and non-excludable.

• Do not forget that both characteristics are needed for a pure public good.

• Do not assume contracting out means no government role: the government may still finance, regulate, and monitor provision.

• Do not draw externality diagrams unless the question clearly asks for broader market failure theory; for 2.9, the syllabus specifies no required diagram or calculation.