国际贸易（ppt课件）：第二章：比较优势理论

2006年版
Chapter 2 Part 1
INTERNATIONAL TRADE THEORY
2006年版
Chapter 2 Basic Analytical Tools
1,General Equilibrium Analysis一般均衡法
1) GEA means analyzing two or more than two related
markets at the same time(eg.Export Market and Import
Market,Goods Market and Factor Market)
2) We usually use the PPF and CIC as the basic tools in the
general equilibrium analysis of international trade,
2,Partial Equilibrium Analysis局部均衡法
1) PEA means only analyzing single market in one time
2) We usually use the Demand Curve and the Supply Curve
as the basic tools in the partial equilibrium analysis,
2006年版
Chapter 2 General Equilibrium Analysis
1,Supply Side,Production Possibility Frontier (PPF)
生产可能性曲线
– 国际贸易实际上是国际市场上的供给（出口）与需求（进口）问
题。为了研究一国能够出口什么，需要进口什么，我们必须先研
究一国的生产能力。在经济学中，为了表现整个国家的能生产什
么，我们常常使用一种称为, 生产可能性曲线, 的图形。
2,Demand Side:Community Indifference Curves
(CIC)社会无差异曲线
– 虽然在一个国家或经济社会里，每个人都有自己的消费偏好，很
难找到一组能反映每一个消费者满足程度的无差异曲线，但我们
仍然能用一幅反映平均消费效用的或反映大多数人消费偏好的无
差异曲线图来分析，我们称之为, 社会无差异曲线, 。社会无差
异曲线反映一国的平均消费偏好。
2006年版
Chapter 2
Production Possibility Frontier
1,Conception,
? PPF:Points describing alternative combinations of
output levels（生产组合） for two different
products to be produced by given resources（既定
的资源条件）
? 生产可能性曲线 （ Production Possibility Frontier,简称
PPF）表明一个国家在充分和有效地使用其所有资
源时能生产的各种商品数量的组合。
QR
Qw
PPF
A
B
C
D
E
The shape of PPF
is decided by the
opportunity of cost
of goods。
2006年版
Chapter 2
Opportunity Cost and PPF
1,Opportunity Cost(机会成本 )
? The cost of an activity in terms of sacrificed
next best alternative uses of the assets involved,
Can also be formulated as,amount of product
2 we must give up to produce a unit of
product 1”,
– （生产一单位商品 1所必须放弃的生产商品 2的
数量）
2006年版
Chapter 2
Opportunity Cost and PPF
1,假设有大米（ Rice）和小麦（ Wheat）两种商品。
那么，大米的, 机会成本, 就是为了多生产一单
位大米而必须放弃小麦的数量（ QW/QR）。
2,从几何概念讲，这也是 PPF的斜率。
PPF
QR
Qw
B
C
QR
Qw
2006年版
Chapter 2
Q
C
Constant Costs
Q
C
Decreasing Costs
Q
C
Increasing Costs
QC
Qw
PPF
QC
Qw
PPF
Qw
QC
PPF
机会成本可以是不变的、递增的或递减的。相应地，生产可
能性曲线也就出现了直线的、外凸的或里凹的不同形状,
2006年版
Chapter 2
Community Indifference Curve
（社会无差异曲线）
Higher
Satisfaction
the points describing same level of satisfaction
(or utility) by given resource,
2006年版
Chapter 2
GE under Autarky
(PPF with constant opportunity costs)
PPF
QR
QW
QR1
QW1
2006年版
Chapter 2
Partial Equilibrium Analysis
1,在局部均衡分析中，我们只分析 某个具体
的商品市场或要素市场 的情况，如中国的
大米市场或中国的小麦市场，而不是同时
分析这两个市场。
2,Partial Equilibrium under autarky
3,Partial Equilibrium under open economy
2006年版
Chapter 2
Partial Equilibrium under autarky
QR
PR/PW
0
S
D
2
3
1
short
surplus
2006年版
Chapter 2
Commodity markets in an Open
Economy
3
X
2
M
Q
R
PR D S
US
Q
R
PR
World Market
Q
R
PR
D S
China
3
2
2006年版
Chapter 2
1,在本书的“国际贸易理论”中，我们主要
运用一般均衡的分析方法来分析贸易利得，
表现为 贸易前后社会无差异曲线水平的变
化 ；
2,在本书的,国际贸易政策”中，我们将运
用局部均衡的方法来分析贸易利得，表现
为 消费者剩余、生产者剩余和净福利的增
减。
2006年版
Chapter 2
Comparative Advantage Model
CHAPTER 2
2006年版
Chapter 2
Limitation of the Smith’s Model
Home Foreign
Labor 100 100
Goods Cloth 100 80
Wheat 50 100
Produc-
tivity Cloth Wheat
In this case,Foreign has the absolute advantage in
both goods (it is very common for a developed
country to have absolute advantages in most
sectors),According to the Smith theory,there will
be no trade.(Really?)
150
1
0.5
1.5
1
2006年版
Chapter 2
Comparative Advantage Theory
1,David Ricardo
2,Comparative Advantage
3,Ricardo’s Model
4,Discussion 1,Misconceptions about
Comparative Advantage
2006年版
Chapter 2
David Ricardo(1772-1823)
1,He was born in London and
was the third of 17 children,
2,had little formal education
and went to work for his
father at the age of 14,
successfully,
3,at the age of 27,turned his
attention to economic,
4,One of the greatest political
economists,
2006年版
Chapter 2
,Principles of
Political Economy,
and Taxation”
2006年版
Chapter 2
自由贸易政策的初次尝试
1,从亚当 ·斯密以后的短时期间，英国人口
的实际增长使谷物需求超过了供给，使
一蒲式耳小麦的价格涨了三倍。于是有
胆量的商人进口国外的小麦和燕麦。
2,海外来的廉价谷物泛滥市场是地主们所
难以忍受的。他们控制议会通过了,谷
物法”,对谷物的进口规定了一个有伸
缩性的税收制度，国外价格越低，则征
税越高。
3,谷物价格飞涨！一蒲式耳小麦的售价等
于一个工人的每周全部工资的两倍。
2006年版
Chapter 2
李嘉图认为,
谷物价格上升会使地主地租收入上升，农业
工人收入上升，同时生活费用上升，工厂工人工
资上升，资本家的利润下降，导致资本积累减少。
所以 李嘉图认为必须废除, 谷物法, 实行自
由贸易。出口工业制成品，进口国外价格低廉的
生活必需品，提高国内生活必需品的供给,使
工资水平下降，利润水平提高，积累增加，社会
财富增加。
1846年，英国议会通过废除, 谷物法, 的法令 。
2006年版
Chapter 2
22$ 25$
25$ 30$
2006年版
Chapter 2
Family Income
5*25=125 5*30=150
5*22=110 5*25=125 510
0*25=0 10*30=300
10*22=220 0*25=0
520
10*25=250 0*30=0
0*22=0 10*25=250 500
2006年版
Chapter 2
Best Cooperation in Family
1,So,the best division of labor in one family is
that women doing housework and men
going out for work,
2.,两利相权取其重，两弊相权取其轻。”
3,Women have comparative advantage in
housework,and men have comparative
advantage in out-house-work,
2006年版
Chapter 2
Ricardo’s Model
?Basic Assumptions
PPF Opportunity Cost Relative Price
Difference in relative price
International Trade under
comparative advantage
Gain from Trade
2006年版
Chapter 2
Basic Assumptions
1,One input(单一要素 ),Labor(L)
2,Two outputs,Wine (Qw) and Cheese(Qc)
3,Two countries,Home and Foreign(*)
4,Costs are constant and there are no economies of
scale,
5,Factors of production are perfectly mobile（生产
要素完全流动）,
6,Other assumptions,
1) Goods are identical（产品同质）,
2) Perfect knowledge（信息完全）,
3) No transport costs（没有运输成本）,
4) No tariffs or other trade barriers（没有贸易壁垒）,
2006年版
Chapter 2
QC
QW
Home’s PPF,aLCQC+ aLwQw≤ L
?当本国完全生产奶酪时,QC=L/aLC
?当本国完全生产葡萄酒时,QW=L/aLW
L/aLW ·
L/aLC ·
Slop of PPF(斜率 ),aLC / aLW
?生产一单位奶酪的机会成本是,
QW /QC= aLC /aLW =
2006年版
Chapter 2
Foreign’s PPF,a*LCQ*C+ a*LwQ*w≤ L*
Q*C
Q*W
L*/a*LW ·
L*/a*LC ·
Slop of PPF*(斜率 ),a*LC / a*LW
?当外国完全生产奶酪时,Q*C=L*/a*LC
?当外国完全生产葡萄酒时,Q*W=L*/a*LW
?外国生产一单位奶酪的机会成本是,
Q*W /Q*C= a*LC /a*LW =
2006年版
Chapter 2
opportunity cost & relative price
? In the autarky,both countries have to produce
both goods for themselves,
? Lets consider the wage of labor in both sector,
WC=PCMPLC; WW= PW MPLW
→ WC=PC/ aLC ; WW= PW /aLW
There must be WC = WW,because labor are perfectly
mobile
So,PC/ aLC = PW /aLW
→ PC/PW = aLC/ aLW
2006年版
Chapter 2
PC/PW = aLC/ aLW
? In a competitive economy,only when the
relative price of goods （ PC/PW） equal to
the opportunity cost of goods （ aLC/ aLw）,
will the labors produce both goods,
? 在一个自由竞争的封闭社会，只有当两种
商品的相对价格等于它们的机会成本时，
劳动者才会同时生产这两种商品。
2006年版
Chapter 2
Relative Price Difference
(相对价格差 )
?本国奶酪的相对价格 PC/PW ＝ aLC/ aLw
?外国奶酪的相对价格 P*C/P*W ＝ a*LC/ a*Lw
?If there is relative price difference between the Home
and the Foreign,international trade may happen,
?如果本国奶酪的相对价格 ＜ 外国奶酪的相对价格
aLC/ aLw ＜ a*LC/ a*Lw
?Home will has the comparative advantage in Cheese
2006年版
Chapter 2
aLC/ aLw ＜ a*LC/ a*Lw
QC
QW
L/aLW ·
L/aLC ·
Slop, aLC / aLW
Home
Q*C
Q*W
L*/a*LW ·
L*/a*LC ·
Slop, a*LC / a*LW
Foreign
?从图形上直观地看，当本国 PPF斜率小于外国 PPF斜率（较平坦）
时，本国在奶酪上有比较优势
2006年版
Chapter 2
2004我国农产品贸易首现贸逆差
?据海关统计
分析，我国
农产品进口
增幅大大超
过出口增幅，
农产品贸易
由 2003年同
期顺差 19.4亿
美元转变为
逆差 55亿美
元。
2006年版
Chapter 2
? 从海关统计数据
来看，高额逆差
的产生主要缘自
三大农产品进口
数量的增加：一
是谷物类，二是
作为工业原料的
棉花和糖，三是
近年来出口快速
增长的畜禽产品。
2006年版
Chapter 2
1,According to Ricardo’s Rule,each country
should specialize in and export the product in
which it has a comparative advantage
(各个国家应专业生产并出口那些他们具有比
较优势的产品）
2,In this case,Home should be specialized in
production of cheese and Foreign should
produce wine,
International Trade under the
comparative advantage
2006年版
Chapter 2
Determining the Relative Price after Trade
奶酪的世界相对
价格,(PC/PW)w
奶酪的相对产
量,QC/QC+W
aLC/aLW
a*LC/a*LW
1.Supply Side(Relative Supply),
1),(PC/PW)w ＜ aLC/aLW,no countries
want to produce cheese
2),(PC/PW)w ＝ aLC/aLW,Home
indifference to both goods
·
3),aLC/aLW ＜ (PC/PW)w ＜ a*LC/a*LW,
Home specialized in cheese,and Foreign
specialized in wine
4),(PC/PW)w = aLC/aLW,Foreign indifference to both goods
5),(PC/PW)w ＞ a*LC/a*LW,both
countries specialized in cheese
RS
RD
RD’
2006年版
Chapter 2
Specializations & Trade
(专业化生产与国际贸易 )
? The normal result of trade is that the
relative price of a traded goods ended up
somewhere in between its pretrade levels in
the two countries,
? aLC/ aLw ＜ (PC/PW)w＜ a*LC/ a*Lw
2006年版
Chapter 2
Will the trade mutual beneficial?
? The mutual gain can be demonstrated in
two ways(两种方法可以证明 ),
1)think of trade as an indirect method of production,
Now,there is 1 hour labor,
Home can produce 1/aLw wine,or
Home can produce 1/ aLC cheese and export it for wine,
(1/ aLC ) × ( PC/PW)w
＞ (1/ aLC ) × PC/PW= (1/ aLC ) × aLC/ aLw
= 1/ aLw
That shows that Home can,produce” wine more
efficiently by making cheese and trading it,
2006年版
Chapter 2
Will the trade mutual beneficial?
2)to examine how trade affects each country’s
possibilities for consumption,
QC
QW
L/aLW ·
L/aLC ·
Pretrade,aLC / aLW
Home
贸易后的专业化生产点
贸易后相对价格线
?贸易扩大了各国消费选择的
范围，因此提高了各国居民
的福利水平。
2006年版
Chapter 2 Example
1,Which country has the comparative advantage in
cloth? And which country has the comparative
advantage in wheat?
2,Please show the effects of trade according to the
comparative advantage theory,
Home Foreign
Labor 100 100
Goods Cloth 100 80
Wheat 50 100
150
2006年版
Chapter 2
First Step:PPF→ Relative Price
Home Foreign
Q
c
QW
0
50 100
50
PPF
PC/PW=0.5
PPF
P*C/P*W=0.67
Q
R
QW
0
50 100
50
100
150
2006年版
Chapter 2
Second Step,
Comparative Advantage → Trade Pattern
? Because 0.5 = PC/PW＜ P*C/P*W=0.67
Home has advantage in cloth;
Foreign has advantage in wheat,
? So,Home should specialize in and export
cloth,and Foreign should specialize in and
export wheat,
? PC/PW＜ (PC/PW)w ＜ P*C/P*W
2006年版
Chapter 2
Third Step:gain from trade
1)think of trade as an indirect method of
production,
? In autarky,Home can use 100 labor
produce 50 wheat;
? Now,home specialize in producing 100
cloth;
? Assume (PC/PW)W=0.6,100 cloth can be
exchange to 60 wheat,which more than
producing by itself,
2006年版
Chapter 2
Third Step:gain from trade
2)to examine how trade affects each country’s
possibilities for consumption,
PC/PW=0.5
Home
Q
c
QW
0
50 100
50
60
(PC/PW)w=0.6
?社会无差异曲线的右移代表
社会满足程度（福利的提高）
2006年版
Chapter 2
Discussion 1,
Misconceptions about CA
1,Productivity and Competitiveness(劳动
生产率和竞争力）
2,The Pauper Labor Argument（贫民劳
动论）
3,Exploitation（剥削）
2006年版
Chapter 2
Evaluation
Alfred Marshall,1842-1924
“That doctrine,.,established by
Ricardo,.,I do not know that
any person has shaken it in
the least,in fact,I do not
myself believe that it has ever
been seriously attacked by
anyone who has taken the
trouble to understand it”