ChExternality课件.pptVIP

Chapter Thirty-Two Externalities Externalities An externality is a cost or a benefit imposed upon someone by actions taken by others. The cost or benefit is thus generated externally to that somebody. An externally imposed benefit is a positive externality. An externally imposed cost is a negative externality. Examples of Negative Externalities Air pollution. Water pollution. Loud parties next door. Traffic congestion. Second-hand cigarette smoke. Increased insurance premiums due to alcohol or tobacco consumption. Examples of Positive Externalities A well-maintained property next door that raises the market value of your property. A pleasant cologne or scent worn by the person seated next to you. Improved driving habits that reduce accident risks. A scientific advance. Externalities and Efficiency Crucially, an externality impacts a third party; i.e. somebody who is not a participant in the activity that produces the external cost or benefit. Externalities and Efficiency Externalities cause Pareto inefficiency; typically too much scarce resource is allocated to an activity which causes a negative externality too little resource is allocated to an activity which causes a positive externality. Externalities and Property Rights An externality will viewed as a purely public commodity. A commodity is purely public if it is consumed by everyone (nonexcludability), and everybody consumes the entire amount of the commodity (nonrivalry in consumption). E.g. a broadcast television program. Inefficiency Negative Externalities Consider two agents, A and B, and two commodities, money and smoke. Both smoke and money are goods for Agent A. Money is a good and smoke is a bad for Agent B. Smoke is a purely public commodity. Inefficiency Negative Externalities Agent A is endowed with $yA. Agent B is endowed with $yB. Smoke intensity is measured on a scale from 0 (no smoke) to 1 (maximum concentration). Inefficiency Negative Externalities Inefficiency Negative Externalities Inef