In the I€wis model, the r:nderdeveloped econorDy consists of two sectors: a tra-ditional, overpopulated n:ral subsistence sector characterized by zero marginal labor productivity-a situ
Trang 1岡 Principles and Concepts
two prominent examples of r,vhat emerged 4s nainsf'eam Western theories of
development during the 1970s: the theoretical and empirical models of stuctr:ral change.
Structural-Ghange Models
Sfircftral-e,hange theory focuses on the mechanism by whicl underdeveloped economies transform their domestic economic stmctures from ahea'lry emphasis
on taditional subsistence agriculture to a more modern, more urbanized, ?Dd more industially diverse manufacturing and service economy It employs the tools of neoclassical price and resource allocation theory and modem economet-rics to describe fuow this transformation process takes place Tlvo well-hown rep-resentative exarnples of the sEmctural-change approach are the "two-sector sur-plus labor" theoretical model of W Arttnr Lewis a.nd the "patterns of develop-ment" empirical analysis of Hollis B Cheuery
The Lewis Theory of Deve:oplTlent FasfF」ИloJθ′
One of the best-hrown early theoretical models of development that focrrsed on
the stnrctural transformation of a primari$ subsistence economy was that
for-mulated by Nobel laureate W Artturr I€wis in the mid-1950s and later modified, foruralized, dDd extended by Ionn Fei and GusUv Ranis'The Lerilis two-sector model became the general theory of the development process in surplus-labor
Third World nations dr:ring most of the 1960s a:rd early 1970s It still has many adhereats today, especially among American development economists
In the I€wis model, the r:nderdeveloped econorDy consists of two sectors: a
tra-ditional, overpopulated n:ral subsistence sector characterized by zero marginal labor productivity-a situation that permits I€wiE to dassify this as surplus labor
in the sense that it can be withdrawn from the agriailtural sector without anyloss
of output-and a high-productivity modem r.uban industrial sector into which labor from the subsistence sector is gradually traasferred- The primary focus of the model is on both the process of labor tansfer and the gronrttr of output arrd employrrent in the modern sector Both labor transfer and modern-sector
emplqrmeat growth are brought about by ouput expansioa in that sector The speed with whidr this srpansion occurs is determined by the rate of indusuial
invesEent and capital accurnulation in the modem sector Such investment is made possible by the excess of modern-sector profits over wages on the assump-tion that capitalists reinvest all their profits Finally, the level of wages in the urban
industrial sector is assr:med to be coDstant and determined as a given premir:m over a fixed average subsistence level of wages in the uaditional agriculnral sec-tor (Icwis assumed that urban wages would have to be at ieast 30% higher thaa
average n-rral income to induce workers to migrate ftom their home areas.) At the constant r.ubanwage, the supply curve of rural labor to the modern sector is con-sidered to be perfectly elastic
■
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Trang 2Theories of Development A Comparative Analysis 35
We can illustate the Leuris model of modern-sector growth in a two-sector economy by using Figr:re 3.1 Consider first the eaditional agricultr:ral sector por-trayed in the h^ro right-side diagrams of Figure 3.1b The upper diagram shows how subsisteace food production varies with increases in labor inputs It is a typical agriculnual production functiou udrere the total output or product (7P) of. food is determined by changes in_the amount of the onlyvariable input, labor (IJ, given a fixed quantity of capital, Kr, a::d nnchanging traditiond tecbaoloTy, fe.h
the lower rigbt diagram, we have the average a.od mar$nat product of labor curves, ,APu atd IyDu, rrytrich are derived from the total product curye shoum
Figure 3.1 The Lewis Model of Modem-sector Growth in aTwo-Sec;tor
Surplus-Labor Economy
TM=r(二MKM,動
K閥>κ崚)Kn PA=′(エルぶbり
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QuanthyOfl」 bOr(Q二″ 〔」 bOuSttdS〕
L」 bor
(a) Modera (indusuial) sector
Quantityof labor (Qad (millions) (bl Traditional (agriolnual) sector
͡
implicit and explicit
độ d ố c
Trang 386 Principles and Concepts
͡
"Ihe qumiV Ofa"“ lm」labOr(Qり aV狙あle iSぬe mme
on both horttnt」 毬es md is●9"ssed h mmbns oF woよぃ,郎 レwヽ お
desdbmg munded"doped∝ onomy、ぬ
“
:e80%わ ∞%ofぬe popuLion uves
Lコ s mよes two assump●ons aboutぬe traこ ond secto■ Fist there is s画‐
レ
"ぬe Ou"■ ∞thatthe m』 red WageiS determmed byぬ e avemge andュ。t
朧t■ere¨ 4Ⅲ m籠 」workes PЮdudュg■ おod,wLiぬ 、並 劇 eq■a町
“
224′ι.1■ e
■ Mqメ ニd PЮ du● Ofむ eSe L WOrbrSお Z】 ● 8 ShOWn h tF bせ 。ndね
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ss of
z"(note血eh。地めnt」 7ら,webqρ ndLworke“ m tte upper i"td上Fan)・
■ e upper‐leiこ賀 薄m ofH諄‐ 3■a POr腱ぃ the tod produ∝ (PЮducion
hndbO cllrvesお rthe moderL d“.● 」
manuL“ 嘔ed g∞
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ぬ 。国 肛
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Ofuba WOrke3,L・ h the LW｀ m“ el the modern‐ 馴誠 Or“Pit」
"K・."aェぃut ofthe remM堅 由コent
Fi諄■3.la O sLi up7なd iOm 7PHκ五)to 7PHヽυ to野'懸κL).The p"c“s
lわOrpЮdud mⅣ
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de壼
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d iOmthe'PrCu"S Of■ E upperdar=ユ Underthe
aSSumPiOn Of pe“
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…
笙」堅望!笙 LEニユ曇型:=型:聖望国2■:」 :型里】エニ
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堕:二望:聖茎l理
=】墨」壼山圭pュ. He“ヽhow Le WSte=:worL
wh ■elowα dialダ肛
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:ofFig肛
"3.la:nd3.lb"p“senヽ■ea"ngel"el of"d mbsぉ tl"hlomehLematonalmョ 1"d。￨ 缶 LH田鵬laぉ
ぬe"お鵬ぬered war mぬ e modem“Pl●li“ se燎 o=.Atthis Ⅷュge the supply of
md hbOrお
“
Sum“
"詭 mb d Orp酎￨“
"daStiq"Shm■ "ぬ
"n口Wピめ ∝kborsupply cuⅣe nrd a"nge mcOme L"mOdem‐e予路 ■ hO■ erWOrdS,L辮∞ ∝OremplorS Cm ｀ むmmeSthat aШЫ bawage
"aS mally
SIPIs mrd w。 ェb"“ ぬeγ‐ ユt｀出山out tな ofおhg wagぃ.Note again hat
色e qumuり of lめor hぬ em」 sedoL Fi●re 3.lb,ヽ 駆P"SSed h ■o“
¨
“
ぬosuds〕 Givm a Ledsupply of“Pid」Ql ぬo Lita s●ge ofmodem‐sec‐
tOrgrmt,■e demad CurVeおrlabOr｀determhed"labOム d∝Lhg m喝 コ‐
dittran.Because prOat_ma コ 」ng E10dern‐ se∝Or empl。丼rs ae assumed t。
"lab。“
rS" e pohtWherethei maづ ユ」Ph"iC」 prOdudヽ eqdtOthe“」
wage Ca,色e po■■F of hter"cion bem∝ nぬ e hbor dem¨d imd supply
∞Ⅳes),tOta mO“m_s∝tOr emplりmentνttlbe eqdtOL.Ъ u modeni_sedor
Ou●ut,Pm,woud be tten"the area boШ ded"POhヽ OD:LFhettue Of
ぬぉo日 Ouり pdd to wOrke薦 ぬe bm Ofwages wOud be eq‐ u」,herefoF,
͡
Trang 4Theories of Development A Comparative Anatysis 87
to the area of the rectaagle OWMFLL.The balance of the output shown bythe area
Wr4F would be the total profits that accrue to the capitalists Because Lewis
assumes that aII of these profits are reinvested, the total capital stock in the
mod-ern sector will rise from Ky1 to KM.This larger capital stock causes the total prod-uct curve of the modem sector to rise to TPL{KM!), rivhich in tum induces a rise in
the marginal product demand curve for labor This outward strift in the labor
demand curve is shor,rrn by line Dz(Kw) in the bottom half of Figure 3.1a- A new equilibrium modern-sector employment level will be established at point Gwith
^[, workers now employed Total ouput rises to TPpor oDrGl while total wages and profits increase to OWMGkandWnDrG, respectivety Once again, these
larg-er (WnaDrQ profits are reinvested, increasing the total capital stock to K,o, shifting
the total product and labor demand curves to TP^lKofi aad to D3Kd,
respective-ly, and raising the level of modern-sector smplolmlent to.t€
This process of modern-sector self-sustaining grorvth and emplo-5pent expar-sion is assrr:ned to continue r:ntil all surplus nrral labor is absorbed in the new industial sector Thereafter, additional workers can be withdrawn from the
agri-cultural sector only at a higher cost of lost food production because the declining labor-to-land ratio rtreans that the marginal product of rural labor is no longer zero Thus the labor supply fluve becomes positively sloped as modern-sector wages and smplolanent continue to gow The stnrctural transformation of the
economy will have taken place, with the bdance of economic activity shifting from traditional nual agriculture to modern urba:r industry
Crtficisms of the Lewis Model
Although the Lewis two-sector development model is simple and roughly reflects
*re historical experience of economic growth in theWest, three of its key assump-tions do not fit the instiflrtional and economic realities of most contemporary
developing cor-rntries.
First, the model implicitly assumes that the rate of labor Ea-nsfer and
employ-rnent creation in the modem sector is proportional to the rate of modern-sector
capital accr:mr:Iation The faster the rate of capital accnmulation, the higher the growth rate of the modem sector and the faster the rate of new job creation But what if capitalist profits are reinvested in rrrore sophisticated laborsaving capital equipment rather than just duplicating the existing capital as is implicitly assumed in the t€wis model? [We ale, of course, here accepting the debatabte assumption that capitalist profits are in fact reinvested in the local economy and
not sent abroad as aform of "capital flight" to be addedto the deposits ofWestem barrks!) Figure 3.2 reproduces the lower, modem-sector diagram of Figr:re 3.1a, onlythis time the labor demand curyes do not shift uaiformly outward but in fact cross Demaad curye Dz(Ku) has a greater negative slope than Dz(Kaa) to reflect the fact that additions to the capital stock embody laborsaving technical progress-that is, X?V/, technology requires much less labor per r.rnit of output tharr tful, technolory does.
We see that even though total output has grown substantiaily (i.e., OD=EL,, is significantly greater than ODTEL,), total wages (OWMELL) and employnent (Ir) remain uachanged AIl of the e)(m outPut accrues to capitelists in the fonn of