社会成本问题-科斯-The-Problem-of-Social-Cost--Ronald-Coase

TheProblemofSocialCostRONALDCOASERonaldCoaseisProfessorEmeritusatUniversityofChicagoLawSchoolandaNobelLaureateinEconomics.ThisarticleisfromTheJournalofLawandEconomics(October1960).Severalpassagesdevotedtoextendeddiscussionsoflegaldecisionshavebeenomitted.I.THEPROBLEMTOBEEXAMINEDThispaperisconcernedwiththoseactionsofbusiness¯rmswhichhaveharm-fule®ectsonothers.Thestandardexampleisthatofafactorythesmokefromwhichhasharmfule®ectsonthoseoccupyingneighbouringproperties.Theeconomicanalysisofsuchasituationhasusuallyproceededintermsofadivergencebetweentheprivateandsocialproductofthefactory,inwhicheconomistshavelargelyfollowedthetreatmentofPigouinTheEconomiesofWelfare.Theconclusiontowhichthiskindofanalysisseemstohaveledmosteconomistsisthatitwouldbedesirabletomaketheownerofthefactoryli-ableforthedamagecausedtothoseinjuredbythesmoke,oralternatively,toplaceataxonthefactoryownervaryingwiththeamountofsmokeproducedandequivalentinmoneytermstothedamageitwouldcause,or¯nally,toexcludethefactoryfromresidentialdistricts(andpresumablyfromotherareasinwhichtheemissionofsmokewouldhaveharmfule®ectsonothers).Itismycontentionthatthesuggestedcoursesofactionareinappropriate,inthattheyleadtoresultswhicharenotnecessarily,orevenusually,desirable.II.THERECIPROCALNATUREOFTHEPROBLEMThetraditionalapproachhastendedtoobscurethenatureofthechoicethathastobemade.ThequestioniscommonlythoughtofasoneinwhichAin°ictsharmonBandwhathastobedecidedis:howshouldwerestrainA?Butthisiswrong.Wearedealingwithaproblemofareciprocalnature.Toavoidtheharmto,Bwouldin°ictharmonA.Therealquestionthathastobedecidedis:shouldAbeallowedtoharmBorshouldBbeallowedtoharmA?Theproblemistoavoidthemoreseriousharm.Iinstancedinmypreviousarticlethecaseofaconfectionerthenoiseandvibrationsfromwhosemachinerydisturbedadoctorinhiswork.Toavoidharmingthedoctorwouldin°ictharmontheconfectioner.Theproblemposedbythiscasewasessentiallywhetheritwasworthwhile,asaresultofrestrictingthemethodsofproductionwhichcouldbeusedbytheconfectioner,tosecuremoredoctoringatthecostofareducedsupplyofconfectioneryproducts.Anotherexampleisa®ordedbytheproblemofstrayingcattlewhichdestroycropsonneighbouringland.Ifitisinevitablethatsomecattlewillstray,allincreaseinthesupplyofmeatcanonly1COASE:TheProblemofSocialCostbeobtainedattheexpenseofadecreaseinthesupplyofcrops.Thenatureofthechoiceisclear:meatorcrops.Whatanswershouldbegivenis,ofcourse,notclearunlessweknowthevalueofwhatisobtainedaswellasthevalueofwhatissacri¯cedtoobtainit.Togiveanotherexample,ProfessorGeorgeJ.Stiglerinstancesthecontaminationofastream.Ifweassumethattheharmfule®ectofthepollutionisthatitkillsthe¯sh,thequestiontobedecidedis:isthevalueofthe¯shlostgreaterorlessthanthevalueoftheproductwhichthecontaminationofthestreammakespossible.Itgoesalmostwithoutsayingthatthisproblemhastobelookedatintotalandatthemargin.III.THEPRICINGSYSTEMWITHLIABILITYFORDAMAGEIproposetostartmyanalysisbyexaminingacaseinwhichmosteconomistswouldpresumablyagreethattheproblemwouldbesolvedinacompeletelysatisfactorymanner:whenthedamagingbusinesshastopayforalldamagecausedandthepricingsystemworkssmoothly(strictlythismeansthattheoperationofapricingsystemiswithoutcost).Agoodexampleoftheproblemunderdiscussionisa®ordedbythecaseofstrayingcattlewhichdestroycropsgrowingonneighbouringland.Letussup-posethatafarmerandcattle-raiserareoperatingonneighbouringproperties.Letusfurthersupposethat,withoutanyfencingbetweentheproperties,anincreaseinthesizeofthecattle-raiser'sherdincreasesthetotaldamagetothefarmer'scrops.Whathappenstothemarginaldamageasthesizeoftheherdincreasesisanothermatter.Thisdependsonwhetherthecattletendtofollowoneanotherortoroamsidebyside,onwhethertheytendtobemoreorlessrestlessasthesizeoftheherdincreasesandonothersimilarfactors.Formyimmediatepurpose,itisimmaterialwhatassumptionismadeaboutmarginaldamageasthesizeoftheherdincreases.Tosimplifytheargument,Iproposetouseanarithmeticalexample.Ishallassumethattheannualcostoffencingthefarmer'spropertyis$9andthepriceofthecropis$1perton.Also,Iassumethattherelationbetweenthenumberofcattleintheherdandtheannualcroplossisasfollows:NUMBERANNUALCROPLOSSPERINHERDCROPLOSSADDITIONALSTEER(STEERS)(TONS)(TONS)1112323634104Giventhatthecattle-raiserisliableforthedamagecaused,theadditionalannualcostimposedonthecattle-raiserifheincreasedhisherdfrom,say,2to3steersis$3andindecidingonthesizeoftheherd,hewilltakethisinto2COASE:TheProblemofSocialCostaccountalongwithhisothercosts.Thatis,hewillnotincreasethesizeoftheherdunlessthevalueoftheadditionalmeatproduced(assumingthatthecattle-raiserslaughtersthecattle)isgreaterthantheadditionalcoststhatthiswillentail,includingthevalueoftheadditionalcropsdestroyed.Ofcourse,if,bytheemploymentofdogs,herdsmen,aeroplanes,mobileradioandothermeans,theamountofdamagecanbereduced,thesemeanswillbeadoptedwhentheircostislessthanthevalueofthecropwhichtheypreventbeinglost.Giventhattheannualcostoffencingis$9,thecattle-raiserwhowishedtohaveaherdwith4steersormorewouldpayforfencingtobeerectedandmaintained,assumingthatothermeansofattainingthesameendwouldnotdosomor