《国际经济学》课程教学课件（讲稿）第3章 国际贸易标准理论 The Standard Theory of International Trade

Chapter 3:The Standard Theory of International Trade （国际贸易的标准理论) Key terms of this charpter Increasing opportunity cost Incomplete specialization Community indifference curve ■Autarky Equilibrium-relative commodity price in isolation Equilibrium-relative commodity price with trade ■Gains from exchange Gains from specialization

1 Chapter 3：The Standard Theory of International Trade （国际贸易的标准理论） Key terms of this charpter: Increasing opportunity cost Incomplete specialization Community indifference curve Autarky Equilibrium-relative commodity price in isolation Equilibrium-relative commodity price with trade Gains from exchange Gains from specialization

3.2 The Production Frontier with Increasing Costs Increasing opportunity Costs: the nation must give up more and more of one commodity to release just enough resources to produce each additional unit of another commodity. Property: negative slope concave from the origin 2

2 3.2 The Production Frontier with Increasing Costs Increasing opportunity Costs : the nation must give up more and more of one commodity to release just enough resources to produce each additional unit of another commodity. Property: ƒ negative slope ƒ concave from the origin

3.2A Illustration of Increasing Costs Y Nation 2 B Nation 1 140 △Y 120 100 80 60 △Y 40 △X 汤 01030507090110130 0 Production frontier of nation 1 and nation 2 with increasing costs Absolute slope of the production frontier at the point of production- Marginal Rate of Transformation(边际转换率) 3

3 Production frontier of nation 1 and nation 2 with increasing costs 3.2A Illustration of Increasing Costs -△ Y 0 10 30 50 70 90 110 130 Y Nation 1 X △ X A B 140 120 100 80 60 40 20 0 - △ X Y Nation 2 △ Y X A’ B’ ™Absolute slope of the production frontier at the point of production—— Marginal Rate of Transformation （边际转换率）

3.2C Reasons for Increasing Opportunity Costs and Different Production Frontier Reasons for Increasing Opportunity Costs: a)Resources or factors are not homogenous b)Resources or factors are not used in the same fixed proportion in the production of all commodities Reasons for Different Production Frontier: a)two nations have different factor endowments b)two nations use different technologies in production

4 3.2C Reasons for Increasing Opportunity Costs and Different Production Frontier ™Reasons for Increasing Opportunity Costs: a) Resources or factors are not homogenous b) Resources or factors are not used in the same fixed proportion in the production of all commodities ™Reasons for Different Production Frontier: a) two nations have different factor endowments b) two nations use different technologies in production

3.3 Community Indifference Curve Community Indifference Curve: the various combinations of two commodities that yield equal satisfaction to the community or nation. Property: ■negative slope convex from the origin ■not cross higher curve refers to higher level of satisfaction 5

5 3.3 Community Indifference Curve Community Indifference Curve: the various combinations of two commodities that yield equal satisfaction to the community or nation. Property: ƒ negative slope ƒ convex from the origin ƒ not cross ƒ higher curve refers to higher level of satisfaction

3.3A Illustration of Community Indifference Curve Textbook:Figure 3.2 (Page 63) Absolute slope of the Community Indifference Curve at the point of consumption Marginal Rate of Substitution(MRS) (边际替代率) 6

6 Textbook: Figure 3.2 （Page 63 ） 3.3A Illustration of Community Indifference Curve ™Absolute slope of the Community Indifference Curve at the point of consumption—— Marginal Rate of Substitution(MRS) （边际替代率）

3.4 Equilibrium in isolation In the absence of trade,a nation is in equilibrium at the point where a Community Indifference curve is tangent to the nation's Production frontier

7 3.4 Equilibrium in isolation ™ In the absence of trade, a nation is in equilibrium at the point where a Community Indifference curve is tangent to the nation’s Production frontier

3.4A Illustration of Equilibrium in isolation B国 140 120 A国 100 80 1% 80H 60 40 40 20 01030507090110130X 0 140 20406080858 孤立均衡时，A国的生产可能性曲线与无差异曲线相切于A点， 即国内均衡点，福利最大化。同样B国的均衡点为A'。 8

8 3.4A Illustration of Equilibrium in isolation 孤立均衡时， A国的生产可能性曲线与无差异曲线相切于 A点， 即国内均衡点，福利最大化。同样 B国的均衡点为A’

3.4B Equilibrium-Relative Commodity Price and Comparative Advantage The common tangent slope of the two curves at the tangency point gives the equilibrium-relative commodity price in isolation.(一国生产可能性曲线和无差 异曲线的公切线的斜率就是孤立均衡的相对商品价格。) Figure 3.3: A国X的孤立均衡相对价格PA=Px/P=1/4, B国X的孤立均衡相对价格PA=Px/P=4, PA<PA,所以A国在商品X上有比较优势。 同理，B国在商品Y上有比较优势。 9

9 3.4B Equilibrium-Relative Commodity Price and Comparative Advantage The common tangent slope of the two curves at the tangency point gives the equilibrium-relative commodity price in isolation. （一国生产可能性曲线和无差 异曲线的公切线的斜率就是孤立均衡的相对商品价格。） Figure 3.3： A 国 X的孤立均衡相对价格 P A= P X / P Y=1/4， B 国 X的孤立均衡相对价格 PA’= P X / P Y=4， P A< PA’,所以 A国在商品 X上有比较优势。 同理， B国在商品 Y上有比较优势

3.5 The Basis for and the Gains from Trade with Increasing Costs The difference in relative commodity prices between two nations reflects their comparative advantage and forms the basis for mutually beneficial trade. lower relative commodity price higher relative commodity price comparative advantage comparative disadvantage 10

10 3.5 The Basis for and the Gains from Trade with Increasing Costs ™ The difference in relative commodity prices between two nations reflects their comparative advantage and forms the basis for mutually beneficial trade. lower relative commodity price comparative advantage higher relative commodity price comparative disadvantage