Externalities, Environmental Policy, and Public Goods – Microeconomics Chapter 5 Study Notes

Externalities, Environmental Policy, and Public Goods

5.1 Externalities and Economic Efficiency

Externalities are unintended side-effects of economic activities that affect third parties not directly involved in the transaction. They can be either positive or negative and have significant implications for economic efficiency.

• Externality: A benefit or cost that affects someone who is not directly involved in the production or consumption of a good or service.

• Private cost: The cost borne by the producer of a good or service.

• Social cost: The total cost of producing a good or service, including both private and external costs.

• Negative externality: Raises social cost above private cost (e.g., pollution).

• Positive externality: Raises social benefit above private benefit (e.g., education).

Example: Pollution from electricity production increases social costs beyond what producers pay, leading to overproduction and deadweight loss.

Graphical Analysis: The market equilibrium occurs where private cost equals demand, but the efficient outcome is where social cost equals demand.

• $S_1$: Marginal private cost

• $S_2$: Marginal social cost

• $Q_{efficient}$: Quantity where marginal social cost equals marginal benefit

• $Q_{market}$: Market equilibrium quantity (too high with negative externality)

Deadweight loss results when the market produces too much (negative externality) or too little (positive externality) compared to the efficient quantity.

5.2 Private Solutions to Externalities: The Coase Theorem

The Coase Theorem suggests that private bargaining can resolve externalities and achieve economic efficiency, provided property rights are well-defined and transaction costs are low.

• Property rights: The rights individuals or businesses have to the exclusive use of their property, including the right to buy or sell it.

• Coase Theorem: If property rights are assigned and transaction costs are low, private parties can negotiate to correct externalities regardless of who holds the rights.

• Transactions costs: Costs in time and resources to negotiate and enforce agreements.

Example: A farmer and a paper mill sharing a stream can negotiate pollution reduction if property rights are clear.

Key Point: The assignment of property rights does not affect the efficient outcome, only the distribution of costs and benefits.

5.3 Government Policies to Deal with Externalities

Government intervention is often necessary when private solutions are impractical due to high transaction costs or diffuse benefits/costs. Policies include taxes, subsidies, and regulations.

• Pigovian tax: A tax imposed to correct a negative externality, set equal to the external cost.

• Pigovian subsidy: A subsidy to encourage activities with positive externalities.

• Command-and-control: Direct regulation, such as limits on emissions or required technology.

• Cap-and-trade: Tradable emissions allowances to achieve pollution reduction at lowest cost.

Example: A tax on pollution shifts the supply curve up, reducing quantity to the efficient level. A subsidy for education shifts the demand curve up, increasing quantity to the efficient level.

Equations:

• Efficient pollution reduction: $MB_{reduction} = MC_{reduction}$

• Pigovian tax: $Tax = External ext{ }Cost$

5.4 Four Categories of Goods

Goods can be classified based on rivalry and excludability, which affects how efficiently markets provide them.

• Rivalry: One person's consumption prevents another's.

• Excludability: Non-payers can be prevented from consuming.

Type	Rival?	Excludable?	Examples
Private Goods	Yes	Yes	Big Macs, running shoes
Common Resources	Yes	No	Tuna in the ocean, public pastureland
Quasi-Public Goods	No	Yes	Cable TV
Public Goods	No	No	National defense, public parks

Efficient Provision: Markets efficiently provide private goods, but public goods and common resources are subject to free-rider problems and overuse (tragedy of the commons).

Tragedy of the Commons: Overconsumption of common resources due to lack of property rights. Solutions include community norms or legal restrictions (taxes, quotas, permits).

Summary Table: Effects of Externalities and Policy Responses

Externality Type	Market Outcome	Efficient Policy
Negative (e.g., pollution)	Overproduction, deadweight loss	Pigovian tax, cap-and-trade, regulation
Positive (e.g., education)	Underproduction, deadweight loss	Pigovian subsidy

Key Formulas

• Efficient output: $MB = MC$

• Deadweight loss: Area between social and private cost/benefit curves for non-optimal quantity

Additional info:

• Market-based policies are generally preferred by economists for their efficiency and incentive alignment.

• Command-and-control policies may be necessary when market-based approaches are impractical.

• Global problems like climate change require coordinated international policy responses.