Market Failure and the Role of Government
What this domain tests
Market failure and government covers externalities, public goods, common resources, asymmetric information, antitrust and regulation, redistribution, and government failure. Questions ask you to identify the efficient quantity, choose the correct policy, and predict deadweight loss.
Externalities and the Coase theorem
- A negative externality makes marginal social cost exceed marginal private cost; the free market overproduces. A Pigouvian tax equal to marginal external cost at the social optimum, or tradable permits, can restore efficiency.
- A positive externality makes marginal social benefit exceed marginal private benefit; the market underproduces. Subsidies or public provision can increase output.
- The Coase theorem says private bargaining can internalize an externality when property rights are clear and transaction costs are low, regardless of who holds the rights.
Public goods, common resources, and information
- A public good is nonrival and nonexcludable; free riders cause underprovision, so government often provides it.
- A common resource is rival but nonexcludable; overuse creates the tragedy of the commons. Remedies include quotas, regulation, and assigning property rights.
- Asymmetric information produces adverse selection before a transaction and moral hazard after it. Warranties, signaling, screening, and regulation are responses.
Government tools and government failure
- Antitrust policy addresses market power; regulation addresses natural monopoly and externalities; taxes and subsidies alter incentives; transfers redistribute income.
- Government failure includes rent seeking, regulatory capture, and inefficient public provision.
Worked example
Demand is P = 100 − Q, marginal private cost is P = 20 + Q, and each unit imposes a $10 external cost. The free market sets 100 − Q = 20 + Q, giving Q = 40 and P = 60. Social marginal cost is P = 30 + Q, so the efficient quantity solves 100 − Q = 30 + Q, giving Q = 35 and P = 65. The market overproduces by 5 units. A Pigouvian tax of $10 per unit shifts private cost to 30 + Q and achieves Q = 35. Deadweight loss at the free-market quantity is ½ × $10 × 5 = $25.
Traps that cost marks
- Confusing public goods with common resources; only public goods are nonrival.
- Applying a subsidy to a negative externality instead of a tax.
- Assuming Coase bargaining works even with high transaction costs or unclear rights.
- Forgetting that a tax corrects quantity but the remaining output still generates some external cost.
- Treating all market power as illegal rather than evaluating consumer harm.