經(jīng)濟學人:信息不對稱之檸檬市場理論與效應(上)Economics

brief:

six

big

ideas.經(jīng)濟概要：六大經(jīng)濟思想。Information

asymmetry:

Secrets

and

agents信息不對稱：秘密和代理George

Akerlof's

1970

paper,“The

Market

forLemons”,

is

a

foundation

stone

of

informationeconomics,

the

first

in

our

series

on

seminaleconomic

ideas.六大經(jīng)濟思想之一，喬治·阿克洛夫1970年的論文——《檸檬市場》，它是信息經(jīng)濟學的一塊基石。In

2007

the

state

of

Washington

introduced

a

new

rule

aimed

at

making

the

labour

marketfairer:

firms

were

banned

from

checking

job

applicants'

credit

scores.2007年，華盛頓州引入了一項旨在讓勞動力市場更公平的新法律：企業(yè)被禁止核查求職者的信用得分。Campaigners

celebrated

the

new

law

as

a

step

towards

equality—an

applicant

with

a

lowcredit

score

is

much

more

likely

to

be

poor,

black

or

young.發(fā)起這項運動的人歡呼慶祝，認為這是通向平等的一步——信用得分低的求職者極有可能是窮人、黑人或者年輕人。Since

then,

ten

other

states

have

followed

suit.自那以后，又有十個州如法炮制。But

when

Robert

Clifford

and

Daniel

Shoag,

two

economists,

recently

studied

the

bans,

theyfound

that

the

laws

left

blacks

and

the

young

with

fewer

jobs,

not

more.但是，日前，當兩位經(jīng)濟學家——羅伯特·克利福德和丹尼爾·紹格——研究了這些禁令時，他們發(fā)現(xiàn)，這些法律帶給黑人和年輕人的工作更少了，而不是更多。Before

1970,

economists

would

not

have

found

much

in

their

discipline

to

help

them

mull

thispuzzle.放在1970年之前，經(jīng)濟學家是不會在這門學科中找到太多的東西來幫助他們仔細思考這個迷的。Indeed,

they

did

not

think

very

hard

about

the

role

of

information

at

all.實際上，他們當時根本就沒有很努力地去思考信息的作用。In

the

labour

market,

for

example,

the

textbooks

mostly

assumed

that

employers

know

theproductivity

of

their

workers—or

potential

workers—and,

thanks

to

competition,

pay

themfor

exactly

the

value

of

what

they

produce.例如，那時的教科書大都假設，在勞動力市場中，雇主知道他們的工人——或者潛在的工人——的生產(chǎn)率，而且，由于競爭，是按照工人所生產(chǎn)的東西的價值給他們開工資的。You

might

think

that

research

upending

that

conclusion

would

immediately

be

celebrated

asan

important

breakthrough.人們可能認為，顛覆這一論斷的研究立即會被譽為一項重大突破。Yet

when,

in

the

late

1960s,

George

Akerlof

wrote

“The

Market

for

Lemons”,

which

did

just

that,and

later

won

its

author

a

Nobel

prize,

the

paper

was

rejected

by

three

leading

journals.然而，當喬治·阿克洛夫于上世紀60年代末期寫出恰恰實現(xiàn)了這種突破并為作者贏得了諾貝爾獎的《檸檬市場》時，這篇論文曾遭到三家主要期刊拒絕。At

the

time,

Mr

Akerlof

was

an

assistant

professor

at

the

University

of

California,

Berkeley;

hehad

only

completed

his

PhD,

at

MIT,

in

1966.那時，阿克洛夫是加州大學伯克利分校的一名助教；僅于1966年在麻省理工完成了博士學位。Perhaps

as

a

result,

the

American

Economic

Review

thought

his

paper's

insights

trivial.也許是因為這個原因，《美國經(jīng)濟評論》認為他的論文的觀點微不足道。The

Review

of

Economic

Studies

agreed.《經(jīng)濟研究評論》同意了這個看法。The

Journal

of

Political

Economy

had

almost

the

opposite

concern:

it

could

not

stomach

thepaper's

implications.《政治經(jīng)濟學雜志》有著幾乎完全相反的擔憂：它可能消化不了這篇論文深遠意義。Mr

Akerlof,

now

an

emeritus

professor

at

Berkeley

and

married

to

Janet

Yellen,

the

chairman

ofthe

Federal

Reserve,

recalls

the

editor's

complaint:“If

this

is

correct,

economics

would

bedifferent.”如今已是伯克利分校名譽教授并同美聯(lián)儲主席珍妮特·耶倫成婚的阿克洛夫還記著那位編輯的不滿：“如果這是正確的，經(jīng)濟學會截然不同?！盜n

a

way,

the

editors

were

all

right.從某種程度上來說，這些編輯當時都是對的。Mr

Akerlof's

idea,

eventually

published

in

the

Quarterly

Journal

of

Economics

in

1970,

was

atonce

simple

and

revolutionary.最終于1970年在《經(jīng)濟學季刊》上發(fā)表了的阿克洛夫的思想即是簡單的，也是革命性的。Suppose

buyers

in

the

used-car

market

value

good

cars—“peaches”—at

$1,000,

and

sellers

atslightly

less.假設，二手車市場中的買方給好車——“桃子”——估價1000美元，賣方要稍微少一點。斯彭斯指出，頂層的工人或許會以收集榮譽——如大學學位——的行為為信號，向企業(yè)展示自己的才華。Crucially,

this

only

works

if

the

signal

is

credible:

if

low-productivity

workers

found

it

easy

toget

a

degree,

then

they

could

masquerade

as

clever

types.關鍵是，這只有在信號是可信的時候才管用：如果低生產(chǎn)力的工人發(fā)現(xiàn)得到學位很容易，他們就可能把自己裝扮成聰明之人。This

idea

turns

conventional

wisdom

on

its

head.這一思想徹底顛覆了傳統(tǒng)的智慧。Education

is

usually

thought

to

benefit

society

by

making

workers

more

productive.一般認為，教育之有益于社會，是因為它讓工人變得更高效。If

it

is

merely

a

signal

of

talent,

the

returns

to

investment

in

education

flow

to

the

students,who

earn

a

higher

wage

at

the

expense

of

the

less

able,

and

perhaps

to

universities,

but

not

tosociety

at

large.如果它僅僅是才華的一個象征，教育投資的所得就會流向?qū)W生，使他們以才華較少之人為代價獲得更高的工資；或者也可能是各個大學，但不是整個社會。One

disciple

of

the

idea,

Bryan

Caplan

of

George

Mason

University,

is

currently

penning

a

bookentitled

“The

Case

Against

Education”.這個思想的一位信徒——喬治梅森大學的布萊恩·卡普蘭目前正在撰寫一本名為《反對教育之種種》的書。(Mr

Spence

himself

regrets

that

others

took

his

theory

as

a

literal

description

of

the

world.)(斯彭斯本人后悔的是，被人把他的理論當成是對這個世界的一種文字描述。)Signalling

helps

explain

what

happened

when

Washington

and

those

other

states

stopped

firmsfrom

obtaining

job-applicants'

credit

scores.信號行為有助于解釋華盛頓等州在阻止企業(yè)獲得求職者信用得分時所發(fā)生了的事情。Credit

history

is

a

credible

signal:

it

is

hard

to

fake,

and,

presumably,

those

with

good

creditscores

are

more

likely

to

make

good

employees

than

those

who

default

on

their

debts.信用歷史是一個可信的信號：它難以造假，而且，可以假定，信用得分良好的人比債務違約的人更有可能成為好雇員。Messrs

Clifford

and

Shoag

found

that

when

firms

could

no

longer

access

credit

scores,

theyput

more

weight

on

other

signals,

like

education

and

experience.克利福德先生和紹格先生發(fā)現(xiàn)，當企業(yè)不再能得到信用得分時，會把重點放在其他信號上面，如教育和資歷。Because

these

are

rarer

among

disadvantaged

groups,

it

became

harder,

not

easier,

for

themto

convince

employers

of

their

worth.因為這些信號在弱勢劣群體中較為少見，因而，對他們而言，讓雇主相信自己的價值就變得更難，而不是更容易。1.nolonger不再例句:Afteraboutthreemonths,Iwas

nolongeraddictedtonicotine.