MiltonFriedman实证经济学的方法论Word文档下载推荐.docx

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mischievouserrors"

andurgestheimportanceof"

recognizinga

distinctpositivescienceofpoliticaleconomy."

1

Thispaperisconcernedprimarilywithcertainmethodological

problemsthatariseinconstructingthe"

distinctpositivescience"

Keynescalledfor-inparticular,theproblemhowtodecidewhether

asuggestedhypothesisortheoryshouldbetentativelyacceptedas

partofthe"

bodyofsystematizedknowledgeconcerningwhatis."

But

theconfusionKeyneslamentsisstillsorifeandsomuchofa

hindrancetotherecognitionthateconomicscanbe,andinpartis,a

positivesciencethatitseemswelltoprefacethemainbodyofthe

paperwithafewremarksabouttherelation,betweenpositiveand

normativeeconomics.

1.THERELATIONBETWEENPOSITIVEANDNORMATIVE

ECONOMICS

Confusionbetweenpositiveandnormativeeconomicsistosome

extentinevitable.Thesubjectmatterofeconomicsisregardedby

almosteveryoneasvitallyimportanttohimselfandwithintherange

ofhisownexperienceandcompetence;

itis

*Ihaveincorporatedbodilyinthisarticlewithoutspecialreference

mostofmybrief"

Comment"

inASurveyofContemporaryEconomics,

Vol.II（B.F.Haley,ed.）（Chicago:

RichardD.Irwin,Inc.,1952）,pp.

455-57.

IamindebtedtoDorothyS.Brady,ArthurF.Burns,andGeorgeJ.

Stiglerforhelpfulcommentsandcriticism.

1.（London:

Macmillan4Co.,1891）,pp.34-35and46.

3

4

thesourceofcontinuousandextensivecontroversyandtheoccasion

forfrequentlegislation.Self-proclaimed"

experts"

speakwithmany

voicesandcanhardlyallberegardedasdisinterested;

inanyevent,

onquestionsthatmattersomuch,"

expert"

opinioncouldhardlybe

acceptedsolelyonfaithevenifthe"

werenearlyunanimous

andclearlydisinterested.2

Theconclusionsofpositiveeconomics

seemtobe,andare,immediatelyrelevanttoimportantnormative

problems,toquestionsofwhatoughttobedoneandhowanygiven

goalcanbeattained.Laymenandexpertsalikeareinevitably

temptedtoshapepositiveconclusionstofitstronglyheldnormative

preconceptionsandtorejectpositiveconclusionsiftheirnormative,

implications-orwhataresaidtobetheirnormativeimplications-

areunpalatable.

Positiveeconomicsisinprincipleindependentofanyparticular

ethicalpositionornormativejudgments.AsKeynessays,itdealswith

whatis,"

notwith"

whatoughttobe."

Itstaskistoprovideasystem

ofgeneralizationsthatcanbeusedtomakecorrectpredictionsabout

theconsequencesofanychangeincircumstances.Itsperformanceis

tobejudgedbytheprecision,scope,andconformitywithexperience

ofthepredictionsityields.Inshort,positiveeconomicsis,orcanbe,

an"

objective"

science,inpreciselythesamesenseasanyofthe

physicalsciences.Ofcourse,thefactthateconomicsdealswiththe

interrelationsofhumanbeings,andthattheinvestigatorishimself

partofthesubjectmatterbeinginvestigatedinamoreintimatesense

thaninthephysicalsciences,raisesspecialdifficultiesinachieving

objectivityatthesametimethatitprovidesthesocialscientistwitha

classofdatanotavailabletothephysical

2.Socialscienceoreconomicsisbynomeanspeculiarinthisrespect-

witnesstheimportanceofpersonalbeliefsandof"

home"

remediesin

medicinewhereverobviouslyconvincingevidencefor"

opinionis

lacking.Thecurrentprestigeandacceptanceoftheviewsofphysical

scientistsintheirfieldsofspecialization-and,,alltoooften,inother

fieldsaswell-derives,notfromfaithalone,butfromtheevidenceof

theirworks,thesuccessoftheirpredictions,andthedramatic

achievementsfromapplying,theirresults.Wheneconomicsseemedto

providesuchevidenceofitsworth,inGreatBritaininthefirsthalfofthe

nineteenthcentury,theprestigeandacceptanceof"

scientificeconomics"

rivaledthecurrentprestigeofthephysicalsciences.

5

scientist.Butneithertheonenortheotheris,inmyview,afundamental

distinctionbetweenthetwogroupsofsciences.3

Normativeeconomicsandtheartofeconomics,ontheotherhand,

cannotbeindependentofpositiveeconomics.Anypolicyconclusion

necessarilyrestsonapredictionabouttheconsequencesofdoingone

thingratherthananother,apredictionthatmustbebased-implicitly

orexplicitly-onpositiveeconomics.Thereisnot,ofcourse,a

one-to-onerelationbetweenpolicyconclusionsandtheconclusions

ofpositiveeconomics;

iftherewere,therewouldbenoseparate

normativescience.Twoindividualsmayagreeontheconsequences

ofaparticularpieceoflegislation.Onemayregardthemasdesirable

onbalanceandsofavorthelegislation;

theother,asundesirableand

soopposethelegislation.

Iventurethejudgment,however,thatcurrentlyintheWestern

world,andespeciallyintheUnitedStates,differencesabout

economicpolicyamongdisinterestedcitizensderivepredominantly

fromdifferentpredictionsabouttheeconomicconsequencesoftaking

action-differencesthatinprinciplecanbeeliminatedbythe

progressofpositiveeconomics-ratherthanfromfundamental

differencesinbasicvalues,differencesaboutwhichmencan

ultimatelyonlyfight.Anobviousandnotunimportantexampleis

minimum-wagelegislation.Underneaththewelterofarguments

offeredforandagainstsuchlegislationthereisanunderlying

consensusontheobjectiveofachievinga"

livingwage"

forall,touse

theambiguousphrasesocommoninsuchdiscussions.Thedifference

ofopinionislargelygroundedonanimplicitorexplicitdifferencein

predictionsabouttheefficacyofthisparticularmeansinfurthering

theagreed-onend.Proponentsbelieve（predict）thatlegalminimum

wagesdiminishpovertybyraisingthewagesofthosereceivingless

thantheminimumwageaswellasofsomereceivingmorethanthe

3.Theinteractionbetweentheobserverandtheprocessobservedthatis

soprominentafeatureofthesocialsciences,besidesitsmoreobvious

parallelinthephysicalsciences,hasamoresubtlecounterpartinthe

indeterminacyprinciplearisingoutoftheinteractionbetweentheprocess

ofmeasurementandthephenomenabeingmeasured.Andbothhavea

counterpartinpurelogicinGodel'

stheorem,assertingtheimpossibility

ofacomprehensiveself-containedlogic.Itisanopenquestionwhether

allthreecanberegardedasdifferentformulationsofanevenmore

generalprinciple.

6

minimumwagewithoutanycounterbalancingincreaseinthenumber

ofpeopleentirelyunemployedoremployedlessadvantageouslythan

theyotherwisewouldbe.Opponentsbelieve（predict）thatlegal

minimumwagesincreasepovertybyincreasingthenumberofpeople

whoareunemployedoremployedlessadvantageouslyandthatthis

morethanoffsetsanyfavorableeffectonthewagesofthosewho

remainemployed.Agreementabouttheeconomicconsequencesofthe

legislationmightnotproducecompleteagreementaboutits

desirability,fordifferencesmightstillremainaboutitspoliticalor

socialconsequences;

but,givenagreementonobjectives,itwould

certainlygoalongwaytowardproducingconsensus.

Closelyrelateddifferencesinpositiveanalysisunderliedivergent

viewsabouttheappropriateroleandplaceoftrade-unionsandthe

desirabilityofdirectpriceandwagecontrolsandoftariffs.Different

predictionsabouttheimportanceofso-called"

economiesofscale"

accountverylargelyfordivergentviewsaboutthedesirabilityor

necessityofdetailedgovernmentregulationofindustryandevenof

socialismratherthanprivateenterprise.Andthislistcouldbe

extendedindefinitely.4Ofcourse,myjudgmentthatthemajor

differencesabouteconomicpolicyintheWesternworldareofthis

kindisitselfa"

positive"

statementtobeacceptedorrejectedonthe

basisofempiricalevidence.

Ifthisjudgmentisvalid,itmeansthataconsensuson"

correct"

economicpolicydependsmuchlessontheprogressofnormative

economicsproperthan,ontheprogressofapositiveeconomics

yieldingconclusionsthatare,anddeservetobe,widelyaccepted.It

meansalsothatamajorreasonfor

4.Onerathermorecomplexexampleisstabilizationpolicy.

Superficially,divergentviewsonthisquestionseemtoreflectdifferences

inobjectives;

butIbelievethatthisimpressionismisleadingandthatat

bottomthedifferentviewsreflectprimarilydifferentjudgmentsaboutthe

sourceoffluctuationsineconomicactivityandtheeffectofalternative

countercyclicalaction.Foronemajorpositiveconsiderationthataccounts

formuchofthedivergencesee"

TheEffectsofaFull-EmploymentPolicy

onEconomicStability:

AFormalAnalysis,"

infra,pp.117-32.Fora

summaryofthepresentstateofprofessionalviewsonthisquestionsee

TheProblemofEconomicInstability,"

areportofasubcommitteeofthe

CommitteeonPublicIssuesoftheAmericanEconomicAssociation,

AmericanEconomicReview,XL（September,1950）,501-38.

7

distinguishingpositive.economicssharplyfromnormativeeconomics

ispreciselythecontributionthatcanther