上海财经大学中级微观经济学课程叶正茂课件

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1、第七章第七章 市场失灵市场失灵u市场失灵的四种情形市场失灵的四种情形:u垄断垄断u外部性（外部效应）外部性（外部效应）u公共物品公共物品u不对称信息不对称信息上海财经大学中级微观经济学课程(叶正茂)7.1 外部性外部性ExternalitiesuAn 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.uAn externally imposed be

2、nefit is a positive externality（正外部性）.uAn externally imposed cost is a negative externality（负外部性）.上海财经大学中级微观经济学课程(叶正茂)Examples of Negative ExternalitiesuAir pollution.uWater pollution.uLoud parties next door.uTraffic congestion.uSecond-hand cigarette smoke.uIncreased insurance premiums due to alcoho

3、l or tobacco consumption.上海财经大学中级微观经济学课程(叶正茂)Examples of Positive ExternalitiesuA well-maintained property next door that raises the market value of your property.uA pleasant cologne（科隆香水）or scent worn by the person seated next to you.uImproved driving habits that reduce accident risks.uA scientific

4、 advance.上海财经大学中级微观经济学课程(叶正茂)Externalities and EfficiencyuExternalities cause Pareto inefficiency;typicallytoo much scarce resource is allocated to an activity which causes a negative externalitytoo little resource is allocated to an activity which causes a positive externality.上海财经大学中级微观经济学课程(叶正茂)I

5、nefficiency&Negative ExternalitiesuConsider two agents,A and B,and two commodities,money and smoke.uBoth smoke and money are goods for Agent A.uMoney is a good and smoke is a bad for Agent B.uSmoke is a purely public commodity.上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negative ExternalitiesuAgent A is endowe

6、d with$yA.uAgent B is endowed with$yB.uSmoke intensity is measured on a scale from 0(no smoke)to 1(maximum concentration).上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negative ExternalitiesOA10SmokemAyAMoney and smoke areboth goods for Agent A.上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negative ExternalitiesOA10SmokemAyA

7、Money and smoke areboth goods for Agent A.Better上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negative ExternalitiesOB10SmokemByBMoney is a good and smokeis a bad for Agent B.Better上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negative ExternalitiesOB10SmokemByBMoney is a good and smokeis a bad for Agent B.Better上海财经大学中级微观经济

8、学课程(叶正茂)Inefficiency&Negative ExternalitiesuWhat are the efficient allocations of smoke and money?上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negative ExternalitiesOA10SmokemAOB10SmokemByAyB上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negative ExternalitiesOA10SmokemAOB10SmokemByAyB上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negativ

9、e ExternalitiesOA10SmokemAOB10SmokemByAyB上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negative ExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocations上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negative ExternalitiesuSuppose there is no means by which money can be exchanged for changes in smoke level.uWhat then is Age

10、nt As most preferred allocation?uIs this allocation efficient?上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negative ExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocations上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negative ExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocationsAs choices上海财经大学中级微观经济学课程(叶正茂)Ineffi

11、ciency&Negative ExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocations As mostpreferred choiceis inefficient上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negative ExternalitiesuContinue to suppose there is no means by which money can be exchanged for changes in smoke level.uWhat is Agent Bs most preferred a

12、llocation?uIs this allocation efficient?上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negative ExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocationsBs choices上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negative ExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocations Bs mostpreferred choice上海财经大学中级微观经济学课程(叶正茂)Inef

13、ficiency&Negative ExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocations Bs mostpreferred choiceis inefficient上海财经大学中级微观经济学课程(叶正茂)Inefficiency&Negative ExternalitiesuSo if A and B cannot trade money for changes in smoke intensity,then the outcome is inefficient.uEither there is too much smoke(A

14、s most preferred choice)or there is too little smoke(Bs choice).上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsuRonald Coases insight is that most externality problems are due to an inadequate specification of property rights and,consequently,an absence of markets in which trade can be used to

15、 internalize external costs or benefits.上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsuNeither Agent A nor Agent B owns the air in their room.uWhat happens if this property right is created and is assigned to one of them?上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsuSuppose Agent B is

16、 assigned ownership of the air in the room.uAgent B can now sell“rights to smoke”.uWill there be any smoking?uIf so,how much smoking and what will be the price for this amount of smoke?上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsuLet p(sA)be the price paid by Agent A to Agent B in order to

17、create a smoke intensity of sA.上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyB上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyB上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyBp(sA)sA上海财经大学中级微观经济学课程(叶正茂)Exter

18、nalities and Property RightsOA10SmokemAOB10SmokemByAyBp(sA)Both agentsgain andthere is apositiveamount ofsmoking.sA上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyBp(sA)sAEstablishinga market fortrading rightsto smoke causes an efficientallocation tobe achieved.上海财经大学中级

19、微观经济学课程(叶正茂)Externalities and Property RightsuSuppose instead that Agent A is assigned the ownership of the air in the room.uAgent B can now pay Agent A to reduce the smoke intensity.uHow much smoking will there be?uHow much money will Agent B pay to Agent A?上海财经大学中级微观经济学课程(叶正茂)Externalities and Pro

20、perty RightsOA10SmokemAOB10SmokemByAyB上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyB上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyBsBp(sB)上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyBp(sB)Both agentsga

21、in andthere is areducedamount ofsmoking.sB上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyBp(sB)Establishinga market fortrading rightsto reducesmoke causes an efficientallocation tobe achieved.sB上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsuNotice that theagent

22、given the property right(asset)is better off than at her own most preferred allocation in the absence of the property right.amount of smoking that occurs in equilibrium depends upon which agent is assigned the property right.上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemB

23、yAyBp(sB)p(sA)sA sBsBsA上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsuIs there a case in which the same amount of smoking occurs in equilibrium no matter which agent is assigned ownership of the air in the room?上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyBp(s

24、B)p(sA)sA=sB上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokeOB10SmokeyAyBp(sB)p(sA)sA=sBFor both agents,the MRS is constant asmoney changes,for given smoke intensity.上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokeOB10SmokeyAyBp(sB)p(sA)sA=sBSo,for both agents,preferences

25、 must bequasilinear in money;U(m,s)=m+f(s).上海财经大学中级微观经济学课程(叶正茂)Coases TheoremuCoases Theorem is:If all agents preferences are quasilinear in money,then the same efficient level of the externality generating commodity is produced no matter which agent is assigned the property right.上海财经大学中级微观经济学课程(叶正

26、茂)Production ExternalitiesuA steel mill produces jointly steel and pollution.uThe pollution adversely affects a nearby fishery.uBoth firms are price-takers.upS is the market price of steel.upF is the market price of fish.上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesucS(s,x)is the steel firms cost of

27、producing s units of steel jointly with x units of pollution.uIf the steel firm does not face any of the external costs of its pollution production then its profit function is and the firms problem is to上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesThe first-order profit-maximizationconditions are上海财经

28、大学中级微观经济学课程(叶正茂)Production ExternalitiesThe first-order profit-maximizationconditions areand上海财经大学中级微观经济学课程(叶正茂)Production Externalitiesstates that the steel firmshould produce the output level of steelfor which price=marginal production cost.上海财经大学中级微观经济学课程(叶正茂)Production Externalitiesstates that t

29、he steel firmshould produce the output level of steelfor which price=marginal production cost.is the rate at which the firmsinternal production cost goes down as thepollution level rises上海财经大学中级微观经济学课程(叶正茂)Production Externalitiesstates that the steel firmshould produce the output level of steelfor

30、which price=marginal production cost.is the rate at which the firmsinternal production cost goes down as thepollution level rises,sois the marginal cost to the firm of pollution reduction（减少）减少）.上海财经大学中级微观经济学课程(叶正茂)Production Externalitiesis the marginal cost to thefirm of pollution reduction.What i

31、s the marginal benefit to the steelfirm from reducing pollution?上海财经大学中级微观经济学课程(叶正茂)Production Externalitiesis the marginal cost to thefirm of pollution reduction.What is the marginal benefit to the steelfirm from reducing pollution?Zero,since the firm does not face itsexternal cost.Hence the steel

32、firm chooses the pollutionlevel for which上海财经大学中级微观经济学课程(叶正茂)Production Externalitiesand the first-order profit-maximizationconditions areandE.g.suppose cS(s,x)=s2+(x-4)2 andpS=12.Then上海财经大学中级微观经济学课程(叶正茂)Production Externalitiesdetermines the profit-max.output level of steel;s*=6.上海财经大学中级微观经济学课程(叶正茂

33、)Production Externalitiesdetermines the profit-max.output level of steel;s*=6.is the marginal cost to the firmfrom pollution reduction.Since it getsno benefit from this it sets x*=4.上海财经大学中级微观经济学课程(叶正茂)Production Externalitiesdetermines the profit-max.output level of steel;s*=6.is the marginal cost

34、to the firmfrom pollution reduction.Since it getsno benefit from this it sets x*=4.The steel firms maximum profit level isthus上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesuThe cost to the fishery of catching f units of fish when the steel mill emits x units of pollution is cF(f,x).Given f,cF(f,x)incr

35、eases with x;i.e.the steel firm inflicts a negative externality on the fishery.上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesuThe cost to the fishery of catching f units of fish when the steel mill emits x units of pollution is cF(f,x).Given f,cF(f,x)increases with x;i.e.the steel firm inflicts a nega

36、tive externality on the fishery.uThe fisherys profit function isso the fisherys problem is to上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesThe first-order profit-maximizationcondition is上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesThe first-order profit-maximizationcondition is上海财经大学中级微观经济学课程(叶正茂)Produ

37、ction ExternalitiesThe first-order profit-maximizationcondition isHigher pollution raises the fisherysmarginal production cost and lowers bothits output level and its profit.This is theexternal cost of the pollution.上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesE.g.suppose cF(f;x)=f2+xf and pF=10.The

38、external cost inflicted on the fisheryby the steel firm is xf.Since the fisheryhas no control over x it must take the steelfirms choice of x as a given.The fisherysprofit function is thus上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesGiven x,the first-order profit-maximizationcondition is上海财经大学中级微观经济学课

39、程(叶正茂)Production ExternalitiesGiven x,the first-order profit-maximizationcondition isSo,given a pollution level x inflicted uponit,the fisherys profit-maximizing outputlevel is上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesGiven x,the first-order profit-maximizationcondition isSo,given a pollution leve

40、l x inflicted uponit,the fisherys profit-maximizing outputlevel isNotice that the fishery produces less,andearns less profit,as the steel firmspollution level increases.上海财经大学中级微观经济学课程(叶正茂)Production Externalities The steel firm,ignoring its external cost inflicted upon the fishery,chooses x*=4,so t

41、he fisherysprofit-maximizing output level given thesteel firms choice of pollution level isf*=3,giving the fishery a maximumprofit level ofNotice that the external cost is$12.上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesuAre these choices by the two firms efficient?uWhen the steel firm ignores the ex

42、ternal costs of its choices,the sum of the two firms profits is$36+$9=$45.uIs$45 the largest possible total profit that can be achieved?上海财经大学中级微观经济学课程(叶正茂)Merger and InternalizationuSuppose the two firms merge to become one.What is the highest profit this new firm can achieve?上海财经大学中级微观经济学课程(叶正茂)Me

43、rger and InternalizationuSuppose the two firms merge to become one.What is the highest profit this new firm can achieve?uWhat choices of s,f and x maximize the new firms profit?上海财经大学中级微观经济学课程(叶正茂)Merger and InternalizationThe first-order profit-maximizationconditions areThe solution is上海财经大学中级微观经济学

44、课程(叶正茂)Merger and InternalizationAnd the merged firms maximum profitlevel isThis exceeds$45,the sum of the non-merged firms.上海财经大学中级微观经济学课程(叶正茂)Merger and InternalizationuMerger has improved efficiency.uOn its own,the steel firm produced x*=4 units of pollution.uWithin the merged firm,pollution prod

45、uction is only xm=2 units.uSo merger has caused both an improvement in efficiency and less pollution production.Why?上海财经大学中级微观经济学课程(叶正茂)Merger and InternalizationThe steel firms profit function is so the marginal cost of producing x unitsof pollution isWhen it does not have to face theexternal costs

46、 of its pollution,the steelfirm increases pollution until this marginalcost is zero;hence x*=4.上海财经大学中级微观经济学课程(叶正茂)Merger and InternalizationIn the merged firm the profit function isThe marginal cost of pollution is thus上海财经大学中级微观经济学课程(叶正茂)Merger and InternalizationIn the merged firm the profit func

47、tion isThe marginal cost of pollution is上海财经大学中级微观经济学课程(叶正茂)Merger and InternalizationIn the merged firm the profit function isThe marginal cost of pollution isThe merged firms marginal pollution costis larger because it faces the full cost ofits own pollution through increased costsof production in

48、 the fishery,so lesspollution is produced by the merged firm.上海财经大学中级微观经济学课程(叶正茂)Merger and InternalizationuMerger therefore internalizes an externality and induces economic efficiency.uHow else might internalization be caused so that efficiency can be achieved?u方法二是收税，见书上方法二是收税，见书上500页。页。u方法三是界定产权。

49、方法三是界定产权。上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesuCoase argues that the externality exists because neither the steel firm nor the fishery owns the water being polluted.uSuppose the property right to the water is created and assigned to one of the firms.Does this induce efficiency?上海财经大

50、学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesuSuppose the fishery owns the water.uThen it can sell pollution rights,in a competitive market,at$px each.uThe fisherys profit function becomes上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesuSuppose the fishery owns the water.uThen it can sell

51、pollution rights,in a competitive market,at$px each.uThe fisherys profit function becomesuGiven pf and px,how many fish and how many rights does the fishery wish to produce?(Notice that x is now a choice variable for the fishery.)上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesThe profit-maxim

52、um conditions are上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesThe profit-maximum conditions areand these give(fish supply)(pollutionright supply)上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesuThe steel firm must buy one right for every unit of pollution it emits so its profit functi

53、on becomesuGiven pf and px,how much steel does the steel firm want to produce and how many rights does it wish to buy?上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesThe profit-maximum conditions are上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesThe profit-maximum conditions areand thes

54、e give(steel supply)(pollutionright demand)上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesIn a competitive market for pollution rightsthe price px must adjust to clear the marketso,at equilibrium,上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesIn a competitive market for pollution right

55、sthe price px must adjust to clear the marketso,at equilibrium,The market-clearing price for pollutionrights is thus上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesIn a competitive market for pollution rightsthe price px must adjust to clear the marketso,at equilibrium,The market-clearing pric

56、e for pollutionrights is thusand the equilibrium quantity of rightstraded is上海财经大学中级微观经济学课程(叶正茂)Coase and Production Externalities上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesSo if ps=12 and pf=10 thenThis is the efficient outcome.上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesuQ:Wou

57、ld it matter if the property right to the water had instead been assigned to the steel firm?uA:Coases Theorem states that the same efficient allocation is achieved whichever of the firms was assigned the property right.(And the asset owner gets richer.)上海财经大学中级微观经济学课程(叶正茂)u如果产权明确界定，外部性就不会带来如果产权明确界定，

58、外部性就不会带来什么问题。什么问题。u但如果产权界定不明确的话，就会带来但如果产权界定不明确的话，就会带来无效率。无效率。u最著名的例子就是最著名的例子就是“公地的悲剧公地的悲剧”。上海财经大学中级微观经济学课程(叶正茂)The Tragedy of the CommonsuConsider a grazing area owned“in common”by all members of a village.uVillagers graze cows on the common.uWhen c cows are grazed,total milk production is f(c),wher

59、e f0 and f”0 and f”0 and f”$100,so supplying the good is Pareto-improving.上海财经大学中级微观经济学课程(叶正茂)Free-RidingBuyDontBuyBuyDontBuyPlayer APlayer B上海财经大学中级微观经济学课程(叶正茂)Free-RidingBuyDontBuyBuyDontBuyPlayer APlayer B(Dont Buy,Dont Buy)is the unique NE.上海财经大学中级微观经济学课程(叶正茂)Free-RidingBuyDontBuyBuyDontBuyPlaye

60、r APlayer BBut(Dont Buy,Dont Buy)is inefficient.上海财经大学中级微观经济学课程(叶正茂)怎样确定公共产品的消费水平Variable Public Good QuantitiesuE.g.how many broadcast TV programs,or how much land to include into a national park.u不同水平的公共产品uc(G)is the production cost of G units of public good.uTwo individuals,A and B.uPrivate consu

61、mptions are xA,xB.上海财经大学中级微观经济学课程(叶正茂)Variable Public Good QuantitiesuBudget allocations must satisfy上海财经大学中级微观经济学课程(叶正茂)Variable Public Good QuantitiesuBudget allocations must satisfyuMRSA&MRSB are A&Bs marg.rates of substitution between the private and public goods.uPareto efficiency condition for

62、 public good supply is 见见530-531页的说明以及图页的说明以及图35.1。上海财经大学中级微观经济学课程(叶正茂)Variable Public Good QuantitiesuHence,necessarily,efficient public good production requiresuSuppose there are n consumers;i=1,n.Then efficient public good production requires 数学证明见数学证明见543页附录页附录上海财经大学中级微观经济学课程(叶正茂)Efficient Publi

63、c Good Supply-the Quasilinear Preferences CaseuTwo consumers,A and B.u 上海财经大学中级微观经济学课程(叶正茂)Efficient Public Good Supply-the Quasilinear Preferences Caseu拟线性偏好的效用表达式：拟线性偏好的效用表达式：u Ui(xi,G)=xi+vi(G)一切公共物品的帕累托有效率一切公共物品的帕累托有效率水平必须满足：水平必须满足：这就是说，私人物品的边际效用总是等于这就是说，私人物品的边际效用总是等于1u所以所以MRSi=vi(G)/G 见书上见书上532

64、页页上海财经大学中级微观经济学课程(叶正茂)Efficient Public Good Supply-the Quasilinear Preferences Caseu v1(G)/G+v2(G)/G=MC(G)u该方程式决定了该方程式决定了G,而与而与x1和和x2根本无根本无关，因此存在一个唯一的公共物品有关，因此存在一个唯一的公共物品有效供给数量。效供给数量。u同时表明：同时表明：Efficient public good supply requires A&B to state truthfully their marginal valuations.上海财经大学中级微观经济学课程(叶正

65、茂)Free-Riding RevisiteduWhen is free-riding individually rational?uIndividuals can contribute only positively to public good supply;nobody can lower the supply level.uIndividual utility-maximization may require a lower public good level.uFree-riding is rational in such cases.u一个人认为另一个人所购买的公共物品正好购一个人

66、认为另一个人所购买的公共物品正好购用，我们可以用下面的图形说明。用，我们可以用下面的图形说明。上海财经大学中级微观经济学课程(叶正茂)Free-Riding RevisiteduGiven A contributes gA units of public good,Bs problem issubject to上海财经大学中级微观经济学课程(叶正茂)Free-Riding RevisitedGxBgABs budget constraint;slope=-1上海财经大学中级微观经济学课程(叶正茂)Free-Riding RevisitedGxBgABs budget constraint;slope=-1is not allowed上海财经大学中级微观经济学课程(叶正茂)Free-Riding RevisitedGxBgABs budget constraint;slope=-1is not allowed上海财经大学中级微观经济学课程(叶正茂)Free-Riding RevisitedGxBgABs budget constraint;slope=-1is not allowed上海