Pigouvian externalities
Pigouvian Externalities Conceptual Overview
Overview
- Pigouvian means "related to Person/Arthur Cecil Pigou."
- Pigouvian externalities describe costs or benefits created by one party but experienced by third parties.
- Classic example: pollution imposes health and environmental costs on people not involved in the original transaction.
Context
- Markets allocate resources through private costs and private benefits.
- When third-party effects are not priced in, market outcomes can become socially inefficient.
- Pigou's contribution was to frame this gap between private and social outcomes in a way policy can address.
Key Principles
- Negative externality: private activity imposes outside costs (for example, emissions).
- Positive externality: private activity creates outside benefits (for example, vaccination spillovers).
- Social cost/benefit can differ from private cost/benefit.
Mechanism
- A Pigouvian tax raises the private cost of a harmful activity to better reflect its social cost.
- A Pigouvian subsidy can encourage activities with positive spillover benefits.
- The policy goal is to align private incentives with social welfare.
Examples
- Carbon taxes on emissions.
- Congestion charges in crowded city centers.
- Subsidies for preventive health measures that reduce broader public costs.
Misconceptions
- Pigouvian policy is not only about taxes; subsidies can also be Pigouvian.
- It is not about punishment; it is about pricing external costs or benefits more accurately.
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