Public goods
Definition
Public good: a good that is both non-excludable and non-rival, so no one can be prevented from consuming it and one person's use does not reduce the amount available to others.
Free-rider: someone who enjoys a good without paying for it, relying on the payments of others.
- A public good has two defining characteristics that a free market cannot cope with.
- It is non-excludable, so once it is provided no one can be prevented from benefiting, meaning a firm cannot withhold it from those who refuse to pay.
- It is non-rival, so one person's use does not reduce the quantity available to others, meaning the marginal cost of serving an extra user is zero.
Key Idea
- Non-excludability removes the ability to charge, so profit-seeking firms have no incentive to supply.
- Non-rivalry means charging any positive price wrongly excludes users who could be served at no extra cost, so a price is inefficient anyway.
The free-rider problem
- A private firm will supply a good only if it can charge a price that covers its costs.
- Because a public good is non-excludable, each consumer can enjoy it without paying, so willingness to pay is never revealed.
- Each consumer is therefore tempted to free-ride, letting others foot the bill while still enjoying the good.
- When everyone reasons this way, too few pay voluntarily, so revenue collapses below the cost of provision.
- The result is a missing market, a complete failure to provide a good society values, which is a source of market failure.
Example
- A coastal town is deciding whether to build a £5m sea wall for flood defence.
- Once built the wall protects every resident, so no household can be excluded from the benefit.
- Each household reasons it will be protected whether or not it contributes, so it waits for others to pay.
- Voluntary contributions therefore fall far short of the £5m and no firm can cover its outlay.
- The market provides no wall at all, so the government builds it and funds it through taxation.
Government provision
- The government corrects the failure by providing the public good directly, either producing it itself or paying a private contractor to build it.
- It pays for provision out of compulsory taxation rather than relying on voluntary payment.
- Because taxation is compulsory, no one can free-ride, so the revenue needed to supply the good is secured and the good is actually provided.
- This is why goods such as national defence, street lighting and flood defences are financed by the state.
Note
- With no market price to guide it, the government must estimate the socially optimal quantity through cost-benefit analysis, which risks over- or under-provision.
- Goods that are only partly non-excludable or non-rival, such as a road that can be tolled, are quasi-public goods.
Public versus merit goods
- A good is a public good because of its characteristics, not because the state happens to supply it.
- Goods such as healthcare and education are merit goods, which are excludable and rival and so can be sold in a market.
- They are provided by the state to raise consumption towards the socially optimal level, not because the market fails to provide them at all.
Does state provision actually improve welfare?
- The case holds strongly for pure public goods, because compulsory taxation removes free-riding and secures a good, such as national defence or flood defence, that the market would supply in zero quantity, so some provision is clearly better than the missing-market outcome.
- However, with no market price to reveal willingness to pay, the government may over- or under-provide, and the decision can be shaped by political priorities or lobbying rather than true social value, so intervention risks government failure.
- Provision is also funded by taxation that carries an opportunity cost and can blunt incentives, and cost-benefit estimates of the optimum are imprecise, so the correction may be imperfect and administratively costly.
- On balance, direct state provision is justified for genuinely non-excludable, non-rival goods because imperfect provision beats none, but the size of the net welfare gain depends on how accurately the optimum is judged, how efficiently the state delivers, and whether the good is truly a public good rather than a chargeable quasi-public good better handled by pricing.
Exam technique
- Prove a good is a public good by showing it is both non-excludable and non-rival, not merely that the government supplies it.
- Then trace the chain from free-riding to a missing market before recommending direct state provision.
Common Mistake
- Do not label every government service a public good, because the test is non-excludability and non-rivalry.
- Merit goods can be sold in a market, whereas pure public goods cannot.
Self review
- What are the two defining characteristics of a public good?
- What is the free-rider problem?
- Why does the free market fail to provide public goods at all?
- How does funding through taxation overcome the free-rider problem?
- Why is a merit good not a pure public good?
