Externalities, Environmental Policy, and Public Goods: Market Failure in Microeconomics

CHAPTER 5: Externalities, Environmental Policy, and Public Goods

Introduction

This chapter explores the concept of market failure in microeconomics, focusing on externalities, environmental policy, and public goods. Understanding these topics is essential for analyzing why markets sometimes fail to allocate resources efficiently and how government intervention can improve outcomes.

Market Performance and Market Failure

Measuring Market Performance

• Market performance refers to the degree to which markets efficiently facilitate arrangements for voluntary trade.

• Efficient markets allocate resources to their most valued uses, maximizing total welfare.

Defining Market Failure

• Market failure occurs when a market leads to choices that do not achieve an efficient use of resources.

• Market failures justify potential government intervention to improve outcomes.

Main Cases of Market Failure

• Externalities

• Public Goods

• Insufficient Competition (e.g., monopoly; covered in other chapters)

• Imperfect Information (covered in other courses)

Externalities

Definition and Types

• Externalities (also called spillovers) are effects of producing or consuming a good that impact others besides the direct buyers and sellers, and are not reflected in the good’s price.

• Negative externalities: Third parties are harmed (e.g., pollution from factories).

• Positive externalities: Third parties benefit (e.g., education, vaccination).

Negative Externalities

Negative externalities can be modeled as an additional cost associated with production or consumption. Common examples include air pollution, water pollution, and overuse of common resources.

• Without government intervention, markets tend to overproduce goods with negative externalities.

• This leads to a quantity greater than the socially optimal level.

Example: Factories emitting pollution impose costs on nearby residents, which are not included in the market price of the factory’s products.

Positive Externalities

Positive externalities can be modeled as an additional benefit associated with consumption or production. Examples include education and vaccination.

• Without government intervention, markets tend to underproduce goods with positive externalities.

• This leads to a quantity less than the socially optimal level.

Example: Vaccination not only protects the individual but also reduces disease transmission, benefiting others.

Graphical Representation

• For negative externalities, the social cost curve lies above the private cost curve.

• For positive externalities, the social benefit curve lies above the private benefit curve.

Formula:

$MSC = MPC + MEC$

Where:

• $MSC$ = Marginal Social Cost

• $MPC$ = Marginal Private Cost

• $MEC$ = Marginal External Cost

$MSB = MPB + MEB$

Where:

• $MSB$ = Marginal Social Benefit

• $MPB$ = Marginal Private Benefit

• $MEB$ = Marginal External Benefit

Government Intervention: Pigovian Taxes and Subsidies

Pigovian Taxes

• Pigovian tax is a tax imposed on activities that generate negative externalities, intended to reduce output to the socially optimal level.

• The tax should equal the marginal external cost.

Formula:

$Tax = MEC$

Example: Taxing plastic bags to reduce environmental damage.

Pigovian Subsidies

• Pigovian subsidy is a subsidy for activities that generate positive externalities, intended to increase output to the socially optimal level.

• The subsidy should equal the marginal external benefit.

Formula:

$Subsidy = MEB$

Example: Subsidizing vaccinations to increase immunization rates.

Coase Theorem

• The Coase Theorem states that if property rights are well-defined and transaction costs are low, parties can negotiate to correct externalities without government intervention.

• Whoever values the right most will end up with it, regardless of initial allocation.

Example: Airline seat reclining rights can be traded between passengers.

Public Goods

Definition and Characteristics

• Public goods are goods that are non-excludable and non-rivalrous.

• Non-excludable: It is not possible to prevent people from using the good.

• Non-rivalrous: One person’s use does not reduce availability for others.

Example: National defense, clean air, lighthouse services.

Types of Goods

Type of Good	Excludability	Rivalry	Example
Pure Private Goods	Excludable	Rivalrous	Food, clothing
Pure Public Goods	Non-excludable	Non-rivalrous	National defense, lighthouse
Common Pool Resources	Non-excludable	Rivalrous	Fisheries, groundwater
Club Goods	Excludable	Non-rivalrous (up to a point)	Private parks, subscription services

Free Rider Problem

• A free rider is a person who consumes a good without paying for it, relying on others to bear the cost.

• Public goods are especially vulnerable to the free rider problem, leading to under-provision in private markets.

Example: National defense benefits all citizens, even those who do not pay taxes.

Common Pool Resources

Definition and Issues

• Common pool resources are non-excludable but rivalrous, such as fisheries and aquifers.

• They are subject to overuse and depletion, a phenomenon known as the "tragedy of the commons."

Example: Over-extraction of water from the Ogallala Aquifer threatens long-term sustainability.

Practice Problems (with Answers)

• Practice Problem #1: If there is a positive externality and no government intervention, firms produce less than the socially optimal quantity.

• Practice Problem #2: Example of a negative externality is someone else getting a vaccination for the person who doesn’t. Answer: False (vaccination is a positive externality).

• Practice Problem #3: A good with high rivalry and high excludability is a club good. Answer: False (this describes a private good).

Summary Table: Types of Goods

Excludability	Rivalry	Type of Good	Example
High	High	Private Good	Food, clothing
Low	Low	Public Good	National defense, lighthouse
Low	High	Common Pool Resource	Fisheries, groundwater
High	Low	Club Good	Private parks, subscription services

Additional info: Academic context and examples have been expanded for clarity and completeness. All formulas are provided in LaTeX format as required.