[经济学]中级微观经济学范里安课件ch 103页

ChapterThirty-ThreeExternalities\nExternalitiesAnexternalityisacostorabenefitimposeduponaconsumerorafirmbyactionstakenbyothers.Thecostorbenefitisthusgeneratedexternallytotheconsumerorthefirm.Anexternallyimposedbenefitisapositiveexternality.Anexternallyimposedcostisanegativeexternality.\nExamplesofNegativeExternalitiesAirpollution.Waterpollution.Loudpartiesnextdoor.Trafficcongestion.Second-handcigarettesmokesufferedbyanon-smoker.Increasedhealthinsurancepremiaduetoalcoholortobaccoconsumption.\nExamplesofPositiveExternalitiesAwell-maintainedpropertynextdoorthatraisesthemarketvalueofyourownproperty.Apleasantcologneorscentwornbythepersonseatednexttoyou.Improveddrivinghabitsthatreduceaccidentrisks.Ascientificadvance.\nExternalitiesandEfficiencyThecrucialfeatureofanexternalityisthatitimpactsathirdparty;thatis,somebodywhoisnotdirectlyaparticipantintheactivitywhichproducestheexternalcostorbenefit.\nExternalitiesandEfficiencyExternalitiescauseParetoinefficiency;typicallytoomuchscarceresourceisallocatedtoanactivitywhichcausesanegativeexternalitytoolittleresourceisallocatedtoanactivitywhichcausesapositiveexternality.\nExternalitiesandPropertyRightsAnexternalitywillbetakentobeapurelypubliccommodity.Acommodityispurelypublicifitisconsumedbyeveryone(nonexcludability),andeverybodyconsumestheentireamountofthecommodity(nonrivalryinconsumption).E.g.abroadcasttelevisionprogram.\nInefficiency&NegativeExternalitiesConsideranexampleoftwoagents,AandB,andtwocommodities,moneyandsmoke.BothsmokeandmoneyaregoodsforAgentA.MoneyisagoodandsmokeisabadforAgentB.Smokeisapurelypubliccommodity.\nInefficiency&NegativeExternalitiesAgentAisendowedwith$yA.AgentBisendowedwith$yB.Smokeintensityismeasuredonascalefrom0(nosmoke)to1(maximumconcentration).\nInefficiency&NegativeExternalitiesOA10SmokemAyAMoneyandsmokearebothgoodsforAgentA.\nInefficiency&NegativeExternalitiesOA10SmokemAyAMoneyandsmokearebothgoodsforAgentA.Better\nInefficiency&NegativeExternalitiesOB10SmokemByBMoneyisagoodandsmokeisabadforAgentB.Better\nInefficiency&NegativeExternalitiesOB10SmokemByBMoneyisagoodandsmokeisabadforAgentB.Better\nInefficiency&NegativeExternalitiesWhataretheefficientallocationsofsmokeandmoney?\nInefficiency&NegativeExternalitiesOA10SmokemAyAOB10SmokemByB\nInefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyB\nInefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyB\nInefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyB\nInefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocations\nInefficiency&NegativeExternalitiesSupposethereisnomechanismbywhichmoneycanbeexchangedforchangesinsmokelevel.WhatthenisAgentA’smostpreferredallocation?Isthisallocationefficient?\nInefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocations\nInefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocationsA’schoices\nInefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocationsA’smostpreferredchoiceisinefficient\nInefficiency&NegativeExternalitiesContinuetosupposethereisnomechanismbywhichmoneycanbeexchangedforchangesinsmokelevel.WhatisAgentB’smostpreferredallocation?Isthisallocationefficient?\nInefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocationsB’schoices\nInefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocationsB’smostpreferredchoice\nInefficiency&NegativeExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocationsB’smostpreferredchoiceisinefficient\nInefficiency&NegativeExternalitiesSoifneitherAnorBcantrademoneyforchangesinsmokeintensity,thentheoutcomeisinefficient.Eitherthereistoomuchsmoke(A’smostpreferredchoice)orthereistoolittlesmoke(B’schoice).\nExternalitiesandPropertyRightsRonaldCoase’sinsightisthatmostexternalityproblemsareduetoaninadequatespecificationofpropertyrightsand,consequently,anabsenceofmarketsinwhichtradecanbeusedtointernalizeexternalcostsorbenefits.\nExternalitiesandPropertyRightsCausingaproducerofanexternalitytobearthefullexternalcostortoenjoythefullexternalbenefitiscalledinternalizingtheexternality.\nExternalitiesandPropertyRightsNeitherAgentAnorAgentBownstheairintheirroom.Whathappensifthispropertyrightiscreatedandisassignedtooneofthem?\nExternalitiesandPropertyRightsSupposethatAgentBisassignedownershipoftheairintheroom.AgentBcannowsell“rightstosmoke”.Willtherebeanysmoking?Ifso,howmuchsmokingwiththerebeandwhatwillbetheequilibriumpriceforthisamountofsmoke?\nExternalitiesandPropertyRightsLetp(sA)bethepricepaidbyAgentAtoAgentBinordertocreateasmokeintensityofsA.\nExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyB\nExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyB\nExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyBp(sA)sA\nExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyBp(sA)Bothagentsgainandthereisapositiveamountofsmoking.sA\nExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyBp(sA)sAEstablishingamarketfortradingrightstosmokecausesanefficientallocationtobeachieved.\nExternalitiesandPropertyRightsSupposeinsteadthatAgentAisassignedtheownershipoftheairintheroom.AgentBcannowpayAgentAtoreducethesmokeintensity.Howmuchsmokingwilltherebe?HowmuchmoneywillAgentBpaytoAgentA?\nExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyB\nExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyB\nExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyBsBp(sB)\nExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyBp(sB)Bothagentsgainandthereisareducedamountofsmoking.sB\nExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyBp(sB)Establishingamarketfortradingrightstoreducesmokecausesanefficientallocationtobeachieved.sB\nExternalitiesandPropertyRightsNoticethattheagentgiventhepropertyright(asset)isbetteroffthanathis/herownmostpreferredallocationintheabsenceofthepropertyright.Noticealsothattheamountofsmokingthatoccursinequilibriumtypicallydependsuponwhichagentisassignedthepropertyright.\nExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyBp(sB)p(sA)sA¹sBsBsA\nExternalitiesandPropertyRightsIsthereacaseinwhichthesameamountofsmokingoccursinequilibriumnomatterwhichoftheagentsisassignedownershipoftheairintheroom?\nExternalitiesandPropertyRightsOA10SmokemAOB10SmokemByAyBp(sB)p(sA)sA=sB\nExternalitiesandPropertyRightsOA10SmokeOB10SmokeyAyBp(sB)p(sA)sA=sBForbothagents,theMRSisconstantasmoneychanges,forgivensmokeintensity.\nExternalitiesandPropertyRightsOA10SmokeOB10SmokeyAyBp(sB)p(sA)sA=sBSo,forbothagents,preferencesmustbequasilinearinmoney;U(m,s)=m+f(s).\nCoase’sTheoremCoase’sTheoremis:Ifallagents’preferencesarequasilinearinmoney,thentheefficientleveloftheexternalitygeneratingcommodityisproducednomattertowhichagentitspropertyrightisassigned.\nProductionExternalitiesConsiderasteelmillwhichproducesjointlysteelandpollution.Thepollutionadverselyaffectsanearbyfishery.Bothfirmsareprice-takers.pSisthemarketpriceofsteel.pFisthemarketpriceoffish.\nProductionExternalitiescS(s,x)isthesteelfirm’scostofproducingsunitsofsteeljointlywithxunitsofpollution.Ifthesteelfirmdoesnotfaceanyoftheexternalcostsofitspollutionproductionthenitsprofitfunctionisandthefirm’sproblemisto\nProductionExternalitiesThefirst-orderprofit-maximizationconditionsare\nProductionExternalitiesThefirst-orderprofit-maximizationconditionsareand\nProductionExternalitiesstatesthatthesteelfirmshouldproducetheoutputlevelofsteelforwhichprice=marginalproductioncost.\nProductionExternalitiesstatesthatthesteelfirmshouldproducetheoutputlevelofsteelforwhichprice=marginalproductioncost.istherateatwhichthefirm’sinternalproductioncostgoesdownasthepollutionlevelrises\nProductionExternalitiesstatesthatthesteelfirmshouldproducetheoutputlevelofsteelforwhichprice=marginalproductioncost.istherateatwhichthefirm’sinternalproductioncostgoesdownasthepollutionlevelrises,soisthemarginalcosttothefirmofpollutionreduction.\nProductionExternalitiesisthemarginalcosttothefirmofpollutionreduction.Whatisthemarginalbenefittothesteelfirmfromreducingpollution?\nProductionExternalitiesisthemarginalcosttothefirmofpollutionreduction.Whatisthemarginalbenefittothesteelfirmfromreducingpollution?Zero,sincethefirmdoesnotfaceitsexternalcost.Hencethesteelfirmchoosesthepollutionlevelforwhich\nProductionExternalitiesandthefirst-orderprofit-maximizationconditionsareandE.g.,supposecS(s,x)=s2+(x-4)2andpS=12.Then\nProductionExternalitiesdeterminestheprofit-max.outputlevelofsteel;s*=6.\nProductionExternalitiesdeterminestheprofit-max.outputlevelofsteel;s*=6.isthemarginalcosttothefirmfrompollutionreduction.Sinceitgetsnobenefitfromthisitsetsx*=4.\nProductionExternalitiesdeterminestheprofit-max.outputlevelofsteel;s*=6.isthemarginalcosttothefirmfrompollutionreduction.Sinceitgetsnobenefitfromthisitsetsx*=4.Thesteelfirm’smaximumprofitlevelisthus\nProductionExternalitiesThecosttothefisheryofcatchingfunitsoffishwhenthesteelmillemitsxunitsofpollutioniscF(f,x).Givenf,cF(f,x)increaseswithx;i.e.thesteelfirminflictsanegativeexternalityonthefishery.\nProductionExternalitiesThecosttothefisheryofcatchingfunitsoffishwhenthesteelmillemitsxunitsofpollutioniscF(f,x).Givenf,cF(f,x)increaseswithx;i.e.thesteelfirminflictsanegativeexternalityonthefishery.Thefishery’sprofitfunctionissothefishery’sproblemisto\nProductionExternalitiesThefirst-orderprofit-maximizationconditionis\nProductionExternalitiesThefirst-orderprofit-maximizationconditionis\nProductionExternalitiesThefirst-orderprofit-maximizationconditionisHigherpollutionraisesthefishery’smarginalproductioncostandlowersbothitsoutputlevelanditsprofit.Thisistheexternalcostofthepollution.\nProductionExternalitiesE.g.,supposecF(f;x)=f2+xfandpF=10.Theexternalcostinflictedonthefisherybythesteelfirmisxf.Sincethefisheryhasnocontroloverxitmusttakethesteelfirm’schoiceofxasagiven.Thefishery’sprofitfunctionisthus\nProductionExternalitiesGivenx,thefirst-orderprofit-maximizationconditionis\nProductionExternalitiesGivenx,thefirst-orderprofit-maximizationconditionisSo,givenapollutionlevelxinflicteduponit,thefishery’sprofit-maximizingoutputlevelis\nProductionExternalitiesGivenx,thefirst-orderprofit-maximizationconditionisSo,givenapollutionlevelxinflicteduponit,thefishery’sprofit-maximizingoutputlevelisNoticethatthefisheryproducesless,andearnslessprofit,asthesteelfirm’spollutionlevelincreases.\nProductionExternalitiesThesteelfirm,ignoringitsexternalcostinflicteduponthefishery,choosesx*=4,sothefishery’sprofit-maximizingoutputlevelgiventhesteelfirm’schoiceofpollutionlevelisf*=3,givingthefisheryamaximumprofitlevelofNoticethattheexternalcostis$12.\nProductionExternalitiesArethesechoicesbythetwofirmsefficient?Whenthesteelfirmignorestheexternalcostsofitschoices,thesumofthetwofirm’sprofitsis$36+$9=$45.Is$45thelargestpossibletotalprofitthatcanbeachieved?\nMergerandInternalizationSupposethetwofirmsmergetobecomeone.Whatisthehighestprofitthisnewfirmcanachieve?\nMergerandInternalizationSupposethetwofirmsmergetobecomeone.Whatisthehighestprofitthisnewfirmcanachieve?Whatchoicesofs,fandxmaximizethenewfirm’sprofit?\nMergerandInternalizationThefirst-orderprofit-maximizationconditionsareThesolutionis\nMergerandInternalizationAndthemergedfirm’smaximumprofitlevelisThisexceeds$45,thesumofthenon-mergedfirms.\nMergerandInternalizationMergerhasimprovedefficiency.Onitsown,thesteelfirmproducedx*=4unitsofpollution.Withinthemergedfirm,pollutionproductionisonlyxm=2units.Somergerhascausedbothanimprovementinefficiencyandlesspollutionproduction.Why?\nMergerandInternalizationThesteelfirm’sprofitfunctionissothemarginalcostofproducingxunitsofpollutionisand,sinceitdoesnothavetofacetheexternalcostsofitspollution,thesteelfirmincreasespollutionuntilthismarginalcostiszero;hencex*=4.\nMergerandInternalizationInthemergedfirmtheprofitfunctionisThemarginalcostofpollutionisthus\nMergerandInternalizationInthemergedfirmtheprofitfunctionisThemarginalcostofpollutionis\nMergerandInternalizationInthemergedfirmtheprofitfunctionisThemarginalcostofpollutionisThemergedfirm’smarginalpollutioncostislargerbecauseitfacesthefullcostofitsownpollutionthroughincreasedcostsofproductioninthefishery,solesspollutionisproducedbythemergedfirm.\nMergerandInternalizationButwhyisthemergedfirm’spollutionlevelofxm=2efficient?\nMergerandInternalizationButwhyisthemergedfirm’spollutionlevelofxm=2efficient?Theexternalcostinflictedonthefisheryisxf,sothemarginalexternalpollutioncostis\nMergerandInternalizationButwhyisthemergedfirm’spollutionlevelofxm=2efficient?Theexternalcostinflictedonthefisheryisxf,sothemarginalexternalpollutioncostisThesteelfirm’scostofreducingpollutionis\nMergerandInternalizationButwhyisthemergedfirm’spollutionlevelofxm=2efficient?Theexternalcostinflictedonthefisheryisxf,sothemarginalexternalpollutioncostisThesteelfirm’scostofreducingpollutionisEfficiencyrequires\nMergerandInternalizationMergerthereforeinternalizesanexternalityandinduceseconomicefficiency.Howelsemightinternalizationbecausedsothatefficiencycanbeachieved?\nTheTragedyoftheCommonsConsideragrazingareaowned“incommon”byallmembersofavillage.Villagersgrazecowsonthecommon.Whenccowsaregrazed,totalmilkproductionisf(c),wheref’>0andf”<0.Howshouldthevillagersgrazetheircowssoastomaximizetheiroverallincome?\nTheTragedyoftheCommonscMilkf(c)\nTheTragedyoftheCommonsNormalizethepriceofaunitofmilkto$1andlettherelativecostofgrazingacowbe$pc.Thentheprofitfunctionfortheentirevillageisandthevillage’sproblemisto\nTheTragedyoftheCommonsTheincome-maximizingnumberofcowstograze,c*,satisfiesi.e.themarginalincomegainfromthelastcowgrazedmustequalthemarginalcostofgrazingit.\nTheTragedyoftheCommonscMilkf(c)pccslope=f’(c*)c*slope=pc\nTheTragedyoftheCommonscMilkf(c)pccslope=f’(c*)c*slope=pcMaximalincomef(c*)\nTheTragedyoftheCommonsForc=c*,theaveragegainpercowgrazedisbecausef’>0andf”<0.\nTheTragedyoftheCommonscMilkf(c)pccslope=f’(c*)c*f(c*)\nTheTragedyoftheCommonsForc=c*,theaveragegainpercowgrazedisbecausef’>0andf”<0.Sotheeconomicprofitfromintroducingonemorecowispositive.Sincenobodyownsthecommon,entryisnotrestricted.\nTheTragedyoftheCommonsEntrycontinuesuntiltheeconomicprofitofgrazinganothercowiszero;thatis,until\nTheTragedyoftheCommonscMilkf(c)pccslope=f’(c*)c*f(c*)\nTheTragedyoftheCommonscMilkf(c)pccslope=f’(c*)c*f(c*)Thecommonsareover-grazed,tragically.\nTheTragedyoftheCommonsThereasonforthetragedyisthatwhenavillagerintroducesonemorecow,thatvillager’sincomeincreases(byf(c)/c-pc)buteveryothervillager’sincomefalls.Thevillagerwhointroducestheextracowtakesnoaccountofthenegativeexternalityinflictedupontherestofthevillage.\nTheTragedyoftheCommonsModern-day“tragediesofthecommons”includeover-fishingthehighseasover-loggingforestsonpubliclandsover-intensiveuseofpublicparks;e.g.Yellowstone.urbantrafficcongestion.