A Level Economics 9708: Public Goods, Non-Excludability and the Free-Rider Problem

Port Elwyn is a small fishing village on an exposed coastline. Local business owners are discussing whether to fund a new sea wall that would protect the village's harbour and homes from storm-surge flooding. No private firm has come forward to build the sea wall and sell protection to individual residents.

(a) Explain, using this example, what is meant by non-excludability and non-rivalry in consumption, the two characteristics that define a public good. [3]

(b) Explain why these two characteristics are likely to create a free-rider problem if Port Elwyn's sea wall were left to be funded voluntarily by local residents and business owners. [3]

(c) Explain why this free-rider problem means the free market is likely to fail to provide the sea wall at all, even though local residents value the flood protection it would offer. [3]

Part (a): Non-excludability and non-rivalry

Non-excludability means that, once the sea wall is built, it is impossible or prohibitively costly to stop any particular resident of Port Elwyn from benefiting from the flood protection it provides. Even a resident who contributed nothing towards its cost still gets the same protection as everyone else.

Non-rivalry means that one resident’s household being protected from a storm surge does not reduce the amount of protection available to any other household. Unlike a private good, where one person’s consumption uses up the good so less is available for others, the sea wall can protect an additional resident at no extra cost and without reducing anyone else’s protection.

Part (b): Why these characteristics create a free-rider problem

Because non-payers cannot be excluded from the sea wall’s protection, each resident can reason that if enough other people pay for the wall to be built, they will receive its full protection whether or not they personally contribute. This gives every individual resident a private incentive to avoid paying and instead “free-ride” on the contributions of others.

If most or all residents think this way, very little money is voluntarily raised, not because residents do not value flood protection, but because each one is individually better off letting somebody else pay for it.

Part (c): Why the free market is likely to fail to provide the sea wall

A private firm considering building the sea wall would normally need to charge individual residents to cover its construction costs. But because it cannot exclude anyone from the protection once built, it cannot guarantee that enough residents will actually pay. The free-rider problem described in part (b) means voluntary revenue is likely to fall well short of the amount needed.

Facing this uncertainty, a profit-seeking firm has no reliable way to recover its costs, so it is unlikely to build the sea wall at all, even if the total value of the flood protection to all of Port Elwyn’s residents combined comfortably exceeds the cost of building it. This complete absence of provision (rather than simply “too little” being provided, as with a normal externality) is why public goods such as this are usually funded directly by government, for example out of general taxation, rather than left to the free market.

Final answers

(a) Non-excludability: non-payers cannot be prevented from benefiting; non-rivalry: one resident’s protection does not reduce protection available to others
(b) Non-payers still benefit, so each resident has an incentive to let others pay. The free-rider problem
(c) A private firm cannot guarantee enough residents will pay voluntarily, so it has no incentive to build the wall. The market is likely to fail to provide it at all, justifying government funding