說明國際貿(mào)易trade theory

1、Gains from Trade in Neoclassical TheoryCopyright 2010 by The McGraw-Hill Companies, Inc. All rights reserved.McGraw-Hill/IrwinChapter 6Learning ObjectivesDescribe economic equilibrium in a country that has no trade.Discover the welfare enhancing impact of opening a country to trade.Demonstrate that

2、either supply differences or demand differences between countries are sufficient to generate a basis for trade.Distinguish the implications of key assumptions in the neoclassical trade model.6.1 Problems With Classical TheoryLabor theory of value is unrealistic.Assumption of constant opportunity cos

3、ts is too restrictive.Demand is largely ignored.6.2 Autarky EquilibriumIn the absence of trade producers will seek to maximize profits.consumers will seek to maximize utility.Production Equilibrium In AutarkyProducers will choose to produce where the relative cost of producing one more unit of X is

4、just equal to the relative price at which the producer can sell a unit of X.That is, equilibrium occurs where MCX/MCY = PX/PY.Producer Equilibrium in AutarkyYXEAutarky Price LinePPFAt point E, MCX/MCY = PX/PY.Consumer Equilibrium in AutarkyGiven relative prices (PX/PY) and e, consumers will choose a

5、 combination of X and Y that puts them on the highest possible community indifference curve.Consumer equilibrium occurs where (MUX/MUY) = (PX/PY).Consumer EquilibriumYXCI1CI2CI3CI4Budget constraintEAutarky EquilibriumIn equilibrium, supply and demand jointly determine PX/PY, and therefore how much X

6、 and Y is produced (and consumed).Autarky EquilibriumYXEX1Y1Community indifferencecurvePPFPrice line6.3 The Introduction of International TradeTrade will cause relative prices to change.Producers will respond to this by altering relative production of goods X and Y.Consumers will respond to this by

7、altering relative consumption of goods X and Y.Production in TradeLets suppose that Country A has a comparative advantage in good X.What will happen to the relative price of good X as Country A moves to trade?It will rise (otherwise, Country A would not wish to produce more of good X in order to exp

8、ort it).Production in TradeYXEX1Y1EX2Y2Intl Price LineAutarky Price LineSteeper intl price linemeans PX/PY has increased.Trade EquilibriumYXEX2Y2CX3Y3FCountry A exports X3X2 (the distance FE), and imports Y3Y2 (the distance FC).exportsimportsMovement From Autarky to TradeMovement to trade causes rel

9、ative price of good X to rise.Higher relative price means more X will be produced, less Y .Higher relative price of X lowers consumption of X, raises consumption of Y.Extra X is exported, shortfall in Y is met by imports.The incentive to trade6.3.1 Production and Consumption Gains from TradeThere ar

10、e two distinct sources of trade gainsConsumption gain: even if producers dont change production levels, welfare is enhanced.Production gain: specialization in the comparative advantage product leads to higher welfare.Consumption GainsYXECEven if producers dont change production levels in response to

11、 a change to (Px/Py)2, the new consumer equilibrium at C is on a higher indifference curve.E(Px/Py)2CProduction GainsYXECEventually producers adjust production levels to E. This permits additional gains to C.E(Px/Py)2CConsumption gains and production gainsCountries A and B TogetherLets continue to s

12、uppose that A has a comparative advantage in good X.Therefore, B must have a comparative advantage in good Y.It must also be true that (PX/PY)A (PX/PY)B.Exports, Imports in A and BCountry ACountry BYYXXX1Y1X4Y4EeX2Y2X5Y5eECcX3Y3Imp.Exp.X6Y6Exp.Imp.6-22Illustration of the Basis for and the Gains from

13、 Trade with Increasing Costs1301105070903010XBAENation 1604020Y800IPA=1/4CIC2CPB=1PB= Pw=1PA2=4Nation 212010060804020X0604020Y80100120140PB2=1A2B2E2CIC3IC2Specialization will continue until relative commodity prices in the two nations es equal at the level at which trade is in equilibrium.Illustrati

14、on of the Basis for and the Gains from Trade with Increasing CostsThe Gains from Exchange and from SpecializationTA7050110300X806020YPW=1PB=PW=1BIIIIECDTwo components: The gains from exchange (AT); The gains from specialization (TE).6.4 Minimum Conditions for TradeTrade will be mutually advantageous

15、 as long as the two countries APRs differ.This can occur because of:differences on the supply side, ordifferences on demand side, orBoth.6.4.1 Identical Demand ConditionsSuppose that the citizens of Country A have the exact same tastes and preferences as the citizens of Country B.Then their communit

16、y indifference curves would be identical.Autarky prices will still differ between the countries as long as the countries differ on their supply sides.Identical Demand ConditionsYXCI1Y2(PX/PY)T(PX/PY)TfFX3Y3X5Y5CI2C, cX26-28Identical Demand ConditionsEven if demand conditions are the same, difference

17、s in supply conditions would cause differences in APRs across countries, and so:Trade could still be mutually advantageous.Implicitly, this is what is going on in the Classical model.6.4.2 Identical Supply ConditionsWhat if two countries have identical technologies and resource endowments?Then their

18、 PPFs would be identical.The Classical model would predict no trade, but what does the Neoclassical model show?Identical Supply ConditionsYXPPF for both countries6-31Identical Supply ConditionsYX(PX/PY)A(CI1)A(CI1)B(PX/PY)BEeY1Y4X1X46-32Identical Supply ConditionsYXEeY1Y4X1X4E, e(PX/PY)TX3Y36-33Identical Supply ConditionsYXEeY1Y4X1X4E, eX3Y3CcX5Y5X2Y2