MankiwEconomicsChap10中山大学吴柏林教授〔曼昆·经济学原理〕绝密资料.ppt

Command-and-Control Policies Usually take the form of regulations: Forbid certain behaviors. Require certain behaviors. Examples: Requirements that all students be immunized. Stipulations on pollution emission levels set by the Environmental Protection Agency (EPA). Market-Based Policies Government uses taxes and subsidies to align private incentives with social efficiency. Pigovian taxes are taxes enacted to correct the effects of a negative externality. Examples of Regulation versus Pigovian tax If the EPA decides it wants to reduce the amount of pollution coming from a specific plant. The EPA could… tell the firm to reduce its pollution by a specific amount (i.e. regulation). levy a tax of a given amount for each unit of pollution the firm emits (i.e. Pigovian tax). Market-Based Policies Tradable pollution permits allow the voluntary transfer of the right to pollute from one firm to another. A market for these permits will eventually develop. A firm that can reduce pollution at a low cost may prefer to sell its permit to a firm that can reduce pollution only at a high cost. The Equivalence of Pigovian Taxes and Pollution Permits... Quantity of Pollution 0 Price of Pollution P Q Demand for pollution rights Pigovian tax (a) Pigovian Tax 2. ...which, together with the demand curve, determines the quantity of pollution. 1. A Pigovian tax sets the price of pollution... Quantity of Pollution 0 Q Demand for pollution rights Supply of pollution permits (b) Pollution Permits Price of Pollution P 2. ...which, together with the demand curve, determines the price of pollution. 1. Pollution permits set the quantity of pollution... Summary When a transaction between a buyer and a seller directly affects a third party, the effect is called an externality. Negative externalities cause the socially optimal quantity in a market to be less than the equilibrium quantity. Positive externalities cause the socially optimal quantity in a market to be greater than the equilibrium qu