Externalities

Concept: Externalities – Social Benefits and Social Costs

Externalities occur when a market transaction imposes a cost or benefit on third parties who are not directly involved in the transaction. These effects can be either negative or positive, leading to market outcomes that are not socially optimal.

• Negative Externality: Imposes an external cost on bystanders (e.g., pollution from a factory).

• Private Cost: The cost borne by the producer of the good.

• External Cost: The cost imposed on others who are not part of the transaction.

• Social Cost: The full cost of a transaction, including both private and external costs.

• Marginal Social Cost (MSC): The additional cost to society from producing one more unit, including both private and external costs.

• Positive Externality: Creates an external benefit for bystanders (e.g., vaccinations, education).

• Private Benefit: The benefit received by the consumer of the good.

• External Benefit: The benefit received by others who are not part of the transaction.

• Social Benefit: The full benefit of a transaction, including both private and external benefits.

• Marginal Social Benefit (MSB): The additional benefit to society from consuming one more unit, including both private and external benefits.

Market Failure: Externalities cause market failures because supply and demand curves do not fully reflect all costs and benefits. This leads to:

• Overproduction in the case of negative externalities

• Underproduction in the case of positive externalities

• Deadweight Loss: The loss of economic efficiency when the equilibrium outcome is not socially optimal.

Externalities often exist when property rights are difficult to enforce or not clearly defined.

Examples of Externalities

• Negative Externality Example: Paper production causing pollution (external cost to society).

• Positive Externality Example: Vaccinations providing herd immunity (external benefit to others).

Practice Questions

• Which of the following is an example of a positive externality? Answer: Jim’s freshly cut hedges make the neighborhood more beautiful.

• If the production of a good causes a negative externality, then the social-cost curve will lie above the supply curve, and the socially optimal quantity is less than the equilibrium quantity.

• Which of the following is true about externalities? Answer: Both positive and negative externalities are not efficient.

Public Solutions to Externalities

Internalizing the Externality

To correct for externalities, governments can intervene to ensure that the full social cost or benefit is reflected in market transactions. This process is called internalizing the externality.

• Command-and-Control Policies: The government requires or forbids certain behaviors (e.g., mandatory education, banning dumping of chemicals).

• Market-Based Policies: The government uses corrective taxes, subsidies, or quantity limits to address externalities.

Pigovian Taxes and Subsidies

• Pigovian Tax: A tax imposed on activities that generate negative externalities, equal to the external cost.

• Pigovian Subsidy: A subsidy given for activities that generate positive externalities, equal to the external benefit.

These policies align private incentives with social efficiency.

Tradeable Pollution Permits

The government can issue a limited number of pollution permits, allowing firms to buy and sell the right to pollute. This creates a market for pollution rights and ensures pollution is limited to the socially optimal quantity.

Practice Questions

• Based on the diagram, an unregulated market would produce: 400 units.

• The figure contains: A positive externality.

• A per-unit subsidy of $20 would result in the production of the socially optimal quantity.

Private Solutions to Externalities

The Coase Theorem

The Coase theorem states that if property rights are clearly defined and transaction costs are low, private parties can negotiate to solve the problem of externalities efficiently, regardless of who holds the property rights.

• Requirements: Clearly defined property rights and low transaction costs (time, money, coordination, resources).

• Example: A barking dog disturbs a neighbor. If property rights are clear, the parties can negotiate a mutually beneficial solution (e.g., the owner pays the neighbor, or vice versa).

• Key Point: The assignment of property rights does not affect efficiency, only the distribution of wealth.

Practice Questions

• A key element of the Coase theorem is: The ability to negotiate at a minimal cost.

• Which of the following is not a way of dealing with externalities? Increasing competition.

• If the assumptions of the Coase theorem are satisfied, then: The assignment of property rights does not matter for efficiency.

• It is possible to remedy a positive externality by: Introducing a subsidy.

• The socially optimal level of pollution: Is above zero.

Additional info: The notes above expand on the brief points in the original material, providing definitions, examples, and context for each concept. The included images are only those that directly reinforce the explanation of externalities, Pigovian taxes/subsidies, and pollution permits.