2.9. Market failure
- Syllabus
- 0455–2027–2028
- Topic
- 2.9
- Level
- —
Learning objectives
2.9.1Definition of market failure• Definition of market failure2.9.2Definitions of terms associated with market failure:• public goods, merit goods, demerit goods, private benefits, external benefits, social benefits, private costs, external costs, social costs, monopoly2.9.3Causes of market failure• causes relating to public goods, merit goods, demerit goods, external costs and external benefits, abuse of monopoly power2.9.4Consequences of market failure• implications of misallocation of resources in relation to:• the over-consumption of demerit goods and goods with external costs• the under-consumption of merit goods and goods with external benefits• the non-provision of public goods• restricted supply causing higher prices under a monopoly Note: demand and supply diagrams relating to market failure are not required.
Recognise market failure
Market failure occurs when the price mechanism does not allocate scarce resources efficiently, so a different allocation could improve social welfare.
| Market outcome | What the failure looks like |
|---|---|
| too much production or consumption | resources are over-allocated to an activity whose full social cost is not reflected in private decisions |
| too little production or consumption | resources are under-allocated because some benefits are ignored or consumers lack information |
| no provision | a socially useful good is not supplied because sellers cannot reliably charge users |
| restricted output and higher price | market power weakens competition and moves output away from the socially efficient level |
A market may reach an equilibrium and still fail: equilibrium means planned demand equals planned supply, while efficiency asks whether resources maximise social welfare. A temporary shortage or surplus alone is not proof of market failure.
Use the language of market failure
Market-failure analysis separates the effects experienced by buyers and sellers from spillover effects on third parties, then combines them to measure the effect on society.
| Term | Precise meaning |
|---|---|
| public good | a good that is non-rival and non-excludable |
| merit good | a good that is more beneficial than consumers realise and is therefore under-consumed |
| demerit good | a good that is more harmful than consumers realise and is therefore over-consumed |
| private benefit | benefit received by the consumer or producer directly involved |
| external benefit | spillover benefit received by a third party |
| social benefit | the total of private benefit and external benefit |
| private cost | cost borne by the consumer or producer directly involved |
| external cost | harmful spillover imposed on a third party |
| social cost | the total of private cost and external cost |
| monopoly | a market dominated by one seller with little or no competition |
Social benefit=Private benefit+External benefit
Social cost=Private cost+External cost
A merit good is not automatically a public good: education can be beneficial yet excludable and rival in capacity. Private versus external describes who experiences an effect, not whether money is paid.
Explain the causes of market failure
Market failure arises when information, prices, payment incentives or competition do not make private decision-makers face the full social costs and benefits of their choices.
| Cause | Missing signal or incentive | Allocation result |
|---|---|---|
| public goods | non-excludability creates a free-rider problem, so providers cannot reliably charge users | non-provision by the market |
| merit goods and imperfect information | consumers underestimate the full benefit | under-consumption and under-production |
| demerit goods and imperfect information | consumers underestimate harm | over-consumption and over-production |
| external costs | decision-makers do not bear all costs, so private cost is below social cost | too many resources enter the activity |
| external benefits | decision-makers are not rewarded for all benefits, so private benefit is below social benefit | too few resources enter the activity |
| abuse of monopoly power | weak competition allows a dominant firm to restrict output and raise price | output is lower and price higher than under effective competition |
Build an explanation as a chain: identify what is ignored or missing, show how that changes the private incentive, then state whether output or consumption becomes too high, too low or absent.
Do not treat every unpopular product or high price as market failure. The explanation must identify a specific information, externality, public-good or market-power mechanism.
Trace the consequences of market failure
The consequence of market failure is misallocation: resources are not directed to the combination of goods and services that produces the greatest social welfare.
| Failure | Consequence | Example chain |
|---|---|---|
| demerit goods or external-cost activities | over-consumption or over-production; too many resources used and third parties harmed | smoking is chosen using private costs and benefits while health effects on others are ignored |
| merit goods or external-benefit activities | under-consumption or under-production; too few resources used and beneficial spillovers are missed | education benefits the learner and wider society, but some wider benefit is absent from the private decision |
| public goods | non-provision, leaving collective needs unmet | non-payers cannot be excluded from national defence, so a private supplier cannot collect enough revenue |
| monopoly power | restricted supply, higher prices and less choice or affordability | weak competitive pressure lets the dominant firm reduce output and charge more |
A strong answer names the affected third party or missing provision and completes the direction of change: which good receives too many or too few resources, and why social welfare falls.
Demand-and-supply diagrams relating to market failure are not required for this Topic. Factor immobility and government remedies belong outside these exact four objectives.