Externalities in Microeconomics

Externalities Overview

• Externalities: A type of market failure where a transaction between a buyer and seller affects a third party who is not directly involved in the transaction.
  • Negative Externality: When the effect on the bystander is adverse (e.g., pollution, noise).
  • Positive Externality: When the effect on the bystander is beneficial (e.g., education, vaccination).

Market Inefficiency

• Market Inefficiency: Occurs when buyers and sellers do not consider external effects, leading to an inefficient market equilibrium.
• Government Intervention: Government action can sometimes improve market outcomes by regulating behavior or through taxation.

Examples of Externalities

Negative Externalities:

1. Air or Water Pollution from factories.
2. Noise from parties or construction.
3. Second-hand smoke.
4. Traffic Accidents caused by reckless driving.

Positive Externalities:

1. Vaccination against contagious diseases.
2. Education leading to societal benefits.
3. Research and technological advancements.
4. Historical Building Restoration.

Social Costs

• Social Cost for negative externalities includes:
  • Private Cost: Cost borne directly by sellers.
  • External Cost: Cost imposed on society by the negative externality.
• The Social Cost Curve is above the supply curve, reflecting the additional burden on society.

Equilibrium and Social Optimum

• Socially Optimal Quantity: The level of production that considers both social costs and benefits.
  • For negative externalities, this quantity is less than the market equilibrium.
  • For positive externalities, this quantity is greater than the market equilibrium.

Internalizing Externalities

• Internalizing Externalities: Adjusting incentives so that individuals account for external effects on others.
  • Example: A $60/ton tax on producers will align social costs with private costs.
  • This adjusts market equilibrium to match the socially optimal quantity.

Public Policies Toward Externalities

Command-and-Control Policies:

• Direct regulations that require or prohibit certain behaviors, such as pollution limits.

Market-Based Policies:

1. Corrective Taxes (Pigovian taxes):
   • Taxing negative externalities to reflect social costs.
   • Example: A corrective tax should equal the external cost.
2. Tradable Pollution Permits:
   • A system where firms can buy and sell permits to pollute, encouraging reduction where it is cheapest.

Coase Theorem

• The Coase Theorem posits that if parties can negotiate without cost, they can internalize externalities efficiently regardless of the initial distribution of rights.
• Example: If Taio plays piano and Zehra is disturbed, they can negotiate a mutually agreeable solution.

Limitations of Private Solutions

• High Transaction Costs: Negotiations can be costly and time-consuming.
• Stubbornness: Parties may not agree easily, leading to bargaining breakdown.
• Coordination Problems: Difficulty in coordinating agreements among multiple stakeholders.

Summary of Externalities

• Negative externalities typically result in a market quantity greater than socially desirable, while positive externalities lead to a market quantity that is less than socially desirable.
• Government intervention may include regulating behavior, applying corrective taxes, or issuing permits to control the inefficiencies those externalities create.
• While theoretical private solutions exist, real-world application often encounters challenges such as high transaction costs and negotiation issues.