Public Goods & Market Failure
- Distinguish public goods from private goods using rivalry and excludability
- Explain the free-rider problem and why markets underprovide public goods
- Identify other sources of market failure, including imperfect information
Rivalry and excludability
Goods are classified by two properties. Rivalry means one person’s use reduces what is available to others; excludability means non-payers can be prevented from consuming. Private goods are both rival and excludable (a sandwich). A public good is non-rival and non-excludable (national defense, a lighthouse): one person’s benefit does not diminish another’s, and no one can be shut out. In between are common resources (rival but non-excludable, like ocean fisheries) and club goods (non-rival but excludable, like cable TV).
The free-rider problem
Because a public good is non-excludable, people can enjoy it without paying — they become free riders. If everyone waits for someone else to pay, too little of the good is provided, and a private market underprovides or fails to provide it entirely, even though its total social benefit exceeds its cost. This is why government typically supplies public goods, funding them through taxes so the free-rider problem does not prevent socially valuable provision. The free-rider problem is the core reason public goods are a classic market failure.
Other market failures
Markets can also fail from imperfect (asymmetric) information, where one party knows more than the other — a used-car seller knowing hidden defects, leading to adverse selection. Common resources suffer the tragedy of the commons: because they are non-excludable but rival, each user overuses them (overfishing, overgrazing), depleting the resource. Market power (monopoly) is another failure, producing too little at too high a price. In each case the unregulated market outcome is not allocatively efficient, opening a potential role for government.
A town is considering building a public fireworks display, which anyone in town can watch for free. Explain, using the properties of public goods, why a private firm is unlikely to provide it and why the town government might.
- 1.Determine the good’s properties: one person watching the fireworks does not reduce others’ ability to watch (non-rival), and no one in town can be prevented from seeing them (non-excludable).
- 2.Non-excludability means a private firm cannot force viewers to pay — everyone can free-ride and watch without buying a ticket.
- 3.With no way to collect revenue from most viewers, a private firm cannot cover its costs, so the market underprovides the display.
- 4.The town government can provide it and fund it through taxes, overcoming the free-rider problem.
A good is non-rival and non-excludable. Economists classify this as a:
Do not equate "public good" with "anything the government provides." The economic definition is strictly non-rival and non-excludable. Many government-provided goods (public schooling, toll roads) are actually rival or excludable and are not public goods in the technical sense.
The free-rider problem causes markets to underprovide public goods primarily because these goods are:
When a question describes a good, test it on both rivalry and excludability before classifying it. The free-rider problem stems from non-excludability; the tragedy of the commons stems from rivalry combined with non-excludability. Naming the right property earns the point.
Answer the 2 checkpoints as you read.
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