2福利经济学基础

第二讲财政学的福利经济学基础（规范分析工具）政府的经济活动多种多样，评价种种不同的政府行为的合理性需要有一个一般性框架。财政学领域的大多数专家使用的评价分析框架是福利经济学。本讲介绍福利经济学的基本内容，用以区分哪些情况市场运作自发带来理想结果，哪些情况市场无法产生理想结果。第二讲财政学的福利经济学基础一、福利经济学（WelfareEconomics）1PureEconomyExchange2ProductionEconomy二、福利经济学第一基本定理三、公平与福利经济学第二基本定理四、市场失败五、福利经济学的局限一、福利经济学•福利经济学:Thebranchofeconomictheoryconcernedwiththesocialdesirabilityofalternativeeconomicstate.1.简单经济交换（没有生产）•埃奇沃斯盒形图EdgeworthBox•帕累托效率Paretoefficientallocation:Nopersoncanbebetteroffwithoutmakinganotherpersonworseoff.•帕累托改进Paretoimprovement:areallocationofresourcesthatmakesonepersonbetteroffwithoutmakinganyoneelseworseoff.•契约曲线Contractcurve:thelocusofalltheParetoefficientpoints.•Paretoefficiencyrequiresthatthemarginalrateofsubstitutionbeequalforallconsumers)()(MRSEvedamafAafMRSEdgeworthBox:Adeviceusedtodepictthedistributionofgoodsinatwogood-twopersonworld.无差异曲线IndifferencecurvesinanEdgeworthBoxMakingAdambetteroffwithoutEvebecomingworseoffMakingEvebetteroffwithoutAdambecomingworseoffMakingbothAdamandEvebetteroffStartingfromadifferentinitialpointEdgeworthBoxAdamEve00’srApplesperyearFigleavesperyearAgEggp1pEp2Ap2p2p3p4kContractcurve:ThelocusofalltheParetoefficientpoints.(契约曲线)EdgeworthBoxAdamEve00’srApplesperyearFigleavesperyearAgEggp1pEp2Ap2p2p3p4ThecontractcurveParetoEfficiencyinConsumption消费效率条件MRSaf=MRSaf•在纯交换经济下，帕累托效率的实现条件为社会所有成员的边际替代率相等AdamEve2生产经济ProductionEconomy（有生产，有交换）•生产可能性曲线Theproductionpossibilitiescurve•边际转换率Themarginalrateoftransformation•产品组合效率条件EfficiencyconditionswithvariableproductionfaMCMCxzwyMRTafEveafAdamafafMRSMRSMRT生产可能性曲线Productionpossibilitiescurve:Agraphthatshowsthemaximumquantityofoneoutputthatcanbeproduced,giventheamountoftheotheroutput.斜率=MRS消费者为了多消费一个苹果，愿意放弃几片无花果叶消费者无差异曲线苹果无花果叶60100生产可能性曲线斜率=MRT为了多生产一个苹果需要放弃几片无花果叶产品组合效率要求MRS=MRTCEfficiencyConditionswithvariableproduction边际转换率MarginalRateofTransformation•MRTaf=Marginalrateoftransformationofapplesforfigleaves•MRTaf=MCa/MCf帕累托效率条件MRTaf=MRSaf=MRSafMCa/MCf=MRSaf=MRSafAdamEveAdamEve二、福利经济学第一基本定理TheFirstFundamentalTheoremofWelfareEconomicsAslongasproducersandconsumersactasperfectcompetitors,thatis,takepricesasgiven,thenundercertainconditions,aParetoefficientallocationofresourcesemerges.•只要生产者和消费者扮演完全竞争者的角色，即接受给定的价格,竞争的经济会“自动”实现帕累托有效的资源配置。率条件的实现竞争可以保证帕累托效追求利润最大化EveafAdamaffaaffafaEveafAdamafMRSMRSPPMRTPPMCMCMRSMRSfaEveaffaAdamafPPMRSPPMRS追求效用最大化三、FairnessandthesecondfundamentaltheoremofwelfareeconomicsIfproperlyfunctioningcompetitivemarketsallocateresourcesefficiently,whatroledoesthegovernmenthavetoplayintheeconomy?效率不是决定某种资源配置好坏的惟一标准。即使经济实现了帕累托效率，为了效用分配更加公平，政府仍有必要干预经济。EfficiencyversusEquityEdgeworthBoxAdamEve00’srApplesperyearFigleavesperyearqp5p3效用可能性曲线:Itshowsthemaximumamountofoneperson’sutilitygiventheotherindividual’sutilitylevel.Eve’sutilityAdam’sutilityUUp3qp5社会无差异曲线SocialIndifferenceCurveEve’sutilityAdam’sutilityW=F(UAdam,UEve)IncreasingsocialwelfareMaximizingSocialWelfareEve’sutilityAdam’sutilityiiiiii福利经济学第二基本定理：在完全竞争的市场条件下，政府所要做的事情是改变个人之间禀赋的初始分配状态，其余的一切都可以由市场来解决。每一种具有帕累托效率的资源配置都可以通过市场机制实现。四、市场失败MarketFailure•市场势力MarketPower–垄断monopoly•市场不存在NonexistenceofMarkets–信息不对称asymmetricinformation–外部性externality–公共商品publicgoodOverview•TheFirstWelfareTheoremofstatesthataproperlyworkingcompetitiveeconomygeneratesaParetoefficientallocationofresourceswithoutanygovernmentintervention.However,itisnotobviousthatanefficientallocationofresourcesispersesociallydesirable;somearguethatfairnessmustalsobeconsidered.Moreover,competitionmaynotholdandnotallmarketsmayexistinreal-worldeconomies.Hence,themarket-determinedallocationofresourcesisunlikelytobeefficient.Thereare,thenopportunitiesforgovernmenttointerveneandenhanceeconomicefficiency.Overview•Thefactthatthemarket-generatedallocationofresourcesisimperfectdoesnotnecessarilymeanthegovernmentiscapableofdoingbetter.•Moreover,governments,likepeople,canmakemistakes.五、福利经济学的局限•Individualisticoutlook:WelfareEconomicsisbasedonanindividualisticsocialphilosophy.•Meritgoods:Acommoditythatoughttobeprovidedevenifpeopledonotdemandit•Resultsorientation:WelfareEconomicsconcernsonlytheresults,itdoesnotpaymuchattentiontotheprocessesusedtoachieveresults.•Coherentframeworkforanalyzingpolicy–Willithavedesirabledistributionalconsequences?–Willitenhanceefficiency?–Canitbedoneatareasonablecost?Homework•Discussionquestions