曼昆《经济学原理》英文版完整讲义丛externalities课件

曼昆经济学原理英文版完整讲义丛externalitiesCopyright2004 South-WesternCopyright 2004 South-WesternCopyright 2004 South-WesternEXTERNALITIES AND MARKET INEFFICIENCY An externality refers to the uncompensated impact of one persons actions on the well-being of a bystander.Externalities cause markets to be inefficient,and thus fail to maximize total surplus.Copyright 2004 South-WesternEXTERNALITIES AND MARKET INEFFICIENCYAn externality arises.when a person engages in an activity that influences the well-being of a bystander and yet neither pays nor receives any compensation for that effect.Copyright 2004 South-WesternEXTERNALITIES AND MARKET INEFFICIENCYWhen the impact on the bystander is adverse,the externality is called a negative externality.When the impact on the bystander is beneficial,the externality is called a positive externality.Copyright 2004 South-WesternEXTERNALITIES AND MARKET INEFFICIENCY Negative ExternalitiesAutomobile exhaustCigarette smokingBarking dogs(loud pets)Loud stereos in an apartment buildingCopyright 2004 South-WesternEXTERNALITIES AND MARKET INEFFICIENCY Positive ExternalitiesImmunizationsRestored historic buildingsResearch into new technologiesFigure 1 The Market for AluminumCopyright 2004 South-WesternQuantity ofAluminum0Price ofAluminumEquilibriumDemand(private value)Supply(private cost)QMARKETCopyright 2004 South-WesternEXTERNALITIES AND MARKET INEFFICIENCYNegative externalities lead markets to produce a larger quantity than is socially desirable.Positive externalities lead markets to produce a larger quantity than is socially desirable.Copyright 2004 South-WesternWelfare Economics:A RecapThe Market for Aluminum The quantity produced and consumed in the market equilibrium is efficient in the sense that it maximizes the sum of producer and consumer surplus.If the aluminum factories emit pollution(a negative externality),then the cost to society of producing aluminum is larger than the cost to aluminum producers.Copyright 2004 South-WesternWelfare Economics:A RecapThe Market for Aluminum For each unit of aluminum produced,the social cost includes the private costs of the producers plus the cost to those bystanders adversely affected by the pollution.Figure 2 Pollution and the Social OptimumCopyright 2004 South-WesternEquilibriumQuantity ofAluminum0Price ofAluminumDemand(private value)Supply(private cost)SocialcostQOPTIMUMOptimumCost ofpollutionQMARKETCopyright 2004 South-WesternNegative Externalities The intersection of the demand curve and the social-cost curve determines the optimal output level.The socially optimal output level is less than the market equilibrium quantity.Copyright 2004 South-WesternNegative ExternalitiesInternalizing an externality involves altering incentives so that people take account of the external effects of their actions.Copyright 2004 South-WesternNegative Externalities Achieving the Socially Optimal OutputThe government can internalize an externality by imposing a tax on the producer to reduce the equilibrium quantity to the socially desirable quantity.Copyright 2004 South-WesternPositive ExternalitiesWhen an externality benefits the bystanders,a positive externality exists.The social value of the good exceeds the private value.Copyright 2004 South-WesternPositive ExternalitiesA technology spillover is a type of positive externality that exists when a firms innovation or design not only benefits the firm,but enters societys pool of technological knowledge and benefits society as a whole.Figure 3 Education and the Social OptimumCopyright 2004 South-WesternQuantity ofEducation0Price ofEducationDemand(private value)SocialvalueSupply(private cost)QMARKETQOPTIMUMCopyright 2004 South-WesternPositive ExternalitiesThe intersection of the supply curve and the social-value curve determines the optimal output level.The optimal output level is more than the equilibrium quantity.The market produces a smaller quantity than is socially desirable.The social value of the good exceeds the private value of the good.Copyright 2004 South-WesternPositive Externalities Internalizing Externalities:SubsidiesUsed as the primary method for attempting to internalize positive externalities.Industrial PolicyGovernment intervention in the economy that aims to promote technology-enhancing industriesPatent laws are a form of technology policy that give the individual(or firm)with patent protection a property right over its invention.The patent is then said to internalize the externality.Copyright 2004 South-WesternPRIVATE SOLUTIONS TO EXTERNALITIESGovernment action is not always needed to solve the problem of externalities.Copyright 2004 South-WesternPRIVATE SOLUTIONS TO EXTERNALITIESMoral codes and social sanctionsCharitable organizationsIntegrating different types of businessesContracting between partiesCopyright 2004 South-WesternThe Coase TheoremThe Coase Theorem is a proposition that if private parties can bargain without cost over the allocation of resources,they can solve the problem of externalities on their own.Transactions CostsTransaction costs are the costs that parties incur in the process of agreeing to and following through on a bargain.Copyright 2004 South-WesternWhy Private Solutions Do Not Always WorkSometimes the private solution approach fails because transaction costs can be so high that private agreement is not possible.Copyright 2004 South-WesternPUBLIC POLICY TOWARD EXTERNALITIESWhen externalities are significant and private solutions are not found,government may attempt to solve the problem mand-and-control policies.market-based policies.Copyright 2004 South-WesternPUBLIC POLICY TOWARD EXTERNALITIESCommand-and-Control PoliciesUsually 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).Copyright 2004 South-WesternPUBLIC POLICY TOWARD EXTERNALITIES Market-Based PoliciesGovernment uses taxes and subsidies to align private incentives with social efficiency.Pigovian taxes are taxes enacted to correct the effects of a negative externality.Copyright 2004 South-WesternPUBLIC POLICY TOWARD EXTERNALITIESExamples of Regulation versus Pigovian Tax If the EPA decides it wants to reduce the amount of pollution coming from a specific plant.The EPA couldtell 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).Copyright 2004 South-WesternPUBLIC POLICY TOWARD EXTERNALITIES Market-Based PoliciesTradable 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.Figure 4 The Equivalence of Pigovian Taxes and Pollution PermitsCopyright 2004 South-WesternQuantity ofPollution0Price ofPollutionDemand forpollution rightsPPigoviantax(a)Pigovian Tax2.which,togetherwith the demand curve,determines the quantityof pollution.1.A Pigoviantax sets theprice ofpollution.QFigure 4 The Equivalence of Pigovian Taxes and Pollution PermitsCopyright 2004 South-WesternQuantity ofPollution0Demand forpollution rightsQSupply ofpollution permits(b)Pollution PermitsPrice ofPollution2.which,togetherwith the demand curve,determines the priceof pollution.1.Pollutionpermits setthe quantityof pollution.PCopyright 2004 South-WesternSummaryWhen 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 quantity.Copyright 2004 South-WesternSummaryThose affected by externalities can sometimes solve the problem privately.The Coase theorem states that if people can bargain without a cost,then they can always reach an agreement in which resources are allocated efficiently.Copyright 2004 South-WesternSummaryWhen private parties cannot adequately deal with externalities,then the government steps in.The government can either regulate behavior or internalize the externality by using Pigovian taxes or by issuing pollution permits.