微观经济之外部效应培训讲义

ChapterThirty-ThreeExternalities外部效应StructureDefinitionConsumptionexternalityProductionexternalityThetragedyofcommonsExternalitiesAnexternalityisacostorabenefitimposeduponsomeonebyactionstakenbyothers.Thecostorbenefitisthusgeneratedexternallytothatsomebody.Anexternallyimposedbenefitisapositiveexternality.Anexternallyimposedcostisanegativeexternality.ExamplesofNegativeExternalitiesAirpollution.Waterpollution.Loudpartiesnextdoor.Trafficcongestion.Second-handcigarettesmoke.ExamplesofPositiveExternalitiesAwell-maintainedpropertynextdoorthatraisesthemarketvalueofyourproperty.Apleasantcologneorscentwornbythepersonseatednexttoyou.Improveddrivinghabitsthatreduceaccidentrisks.Education.ExternalitiesandEfficiencyCrucially,anexternalityimpactsathirdparty;i.e.somebodywhoisnotaparticipantintheactivitythatproducestheexternalcostorbenefit.ExternalitiesandEfficiencyExternalitiescauseParetoinefficiency;typically–toomuchscarceresourceisallocatedtoanactivitywhichcausesanegativeexternality–toolittleresourceisallocatedtoanactivitywhichcausesapositiveexternality.ExternalitiesandPropertyRightsAnexternalityisviewedasapurelypubliccommodity.Acommodityispurelypublicif–itisconsumedbyeveryone(nonexcludability),and–everybodyconsumestheentireamountofthecommodity(nonrivalryinconsumption).E.g.abroadcasttelevisionprogram.ConsumptionExternalityParetoefficientamountofsmokeInefficientequilibriumwithnegativeexternalityPropertyrightsandpricemechanismQuasi-linearutilityandtheCoasetheorem(科斯定理)Considertwoagents,AandB,andtwocommodities,moneyandsmoke.BothsmokeandmoneyaregoodsforAgentA.MoneyisagoodandsmokeisabadforAgentB.Smokeisapurelypubliccommodity.ConsumptionExternalityAgentAisendowedwith$yA.AgentBisendowedwith$yB.Smokeintensityismeasuredonascalefrom0(nosmoke)to1(maximumconcentration).ConsumptionExternalityOA10SmokemAyAMoneyandsmokearebothgoodsforAgentA.ConsumptionExternalityOA10SmokemAyAMoneyandsmokearebothgoodsforAgentA.ConsumptionExternalityOB10SmokemByBMoneyisagoodandsmokeisabadforAgentB.ConsumptionExternalityOB10SmokemByBMoneyisagoodandsmokeisabadforAgentB.ConsumptionExternalityParetoEfficientAllocationsWhataretheefficientallocationsofsmokeandmoney?OA10SmokemAyAOB10SmokemByBParetoEfficientAllocationsOA10SmokemAOB10SmokemByAyBParetoEfficientAllocationsOA10SmokemAOB10SmokemByAyBParetoEfficientAllocationsOA10SmokemAOB10SmokemByAyBParetoEfficientAllocationsOA10SmokemAOB10SmokemByAyBEfficientallocationsParetoEfficientAllocationsInefficiency&NegativeExternalitiesSupposethereisnomeansbywhichmoneycanbeexchangedforchangesinsmokelevel.WhatthenisAgentA’smostpreferredallocation?Isthisallocationefficient?Inefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocationsInefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocationsA’schoicesInefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocationsA’smostpreferredchoiceisinefficientInefficiency&NegativeExternalitiesContinuetosupposethereisnomeansbywhichmoneycanbeexchangedforchangesinsmokelevel.WhatisAgentB’smostpreferredallocation?Isthisallocationefficient?Inefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocationsB’schoicesInefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocationsB’smostpreferredchoiceInefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocationsB’smostpreferredchoiceisinefficientInefficiency&NegativeExternalitiesSoifAandBcannottrademoneyforchangesinsmokeintensity,thentheoutcomeisinefficient.Eitherthereistoomuchsmoke(A’smostpreferredchoice)orthereistoolittlesmoke(B’schoice).ExternalitiesandPropertyRightsRonaldCoase’sinsightisthatmostexternalityproblemsareduetoaninadequatespecificationofpropertyrightsand,consequently,anabsenceofmarketsinwhichtradecanbeusedtointernalizeexternalcostsorbenefits.ExternalitiesandPropertyRightsCausingaproducerofanexternalitytobearthefullexternalcostortoenjoythefullexternalbenefitiscalledinternalizingtheexternality(外部效应内部化).ExternalitiesandPropertyRightsNeitherAgentAnorAgentBownstheairintheirroom.Whathappensifthispropertyrightiscreatedandisassignedtooneofthem?ExternalitiesandPropertyRightsSupposeAgentBisassignedownershipoftheairintheroom.AgentBcannowsell“rightstosmoke”.Willtherebeanysmoking?Ifso,howmuchsmokingandwhatwillbethepriceforthisamountofsmoke?ExternalitiesandPropertyRightsLetp(sA)bethepricepaidbyAgentAtoAgentBinordertocreateasmokeintensityofsA.ExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyBExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyBExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyBp(sA)sAExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyBp(sA)Bothagentsgainandthereisapositiveamountofsmoking.sAExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyBp(sA)sAEstablishingamarketfortradingrightstosmokecausesanefficientallocationtobeachieved.ExternalitiesandPropertyRightsSupposeinsteadthatAgentAisassignedtheownershipoftheairintheroom.AgentBcannowpayAgentAtoreducethe