Chapter 03Why Everybody Trades: Comparative AdvantageOverviewThis chapter extends the analysis of international trade to consider trade in a multiple-product economy. An economy composed of two products is useful to bring out insights about international trade. This general equilibrium approach explicitly shows the effects of resource reallocations between industries. The chapter culminates in showing the importance of comparative advantage for understanding why countries trade.The story begins with Adam Smith and absolute advantage. (A box on mercantilism summarizes the view that Smith opposed and shows how mercantilist thinking continues today.) The analysis focuses on the productivity of labor (output per hour) in producing each of two products (wheat and cloth) in two countries (the United States and the rest of the world). Smith examined the case of absolute advantage, in which labor productivity in producing one product is higher in one country and labor productivity in producing the other product is higher in the other country. With no trade each country must produce both products to meet national demands. The discussion of the Smith case focuses on the increase in global production efficiency achieved by shifting production in each country toward the product in which it has the higher labor productivity. National demands can be met by international trade—apparently excess supplies can be exported and apparently excess demands can be met by imports. The increase in total world production is the evidence of gains from international trade.Smith's approach does not indicate what would happen if the same country has absolute advantage in both products. Ricardo took up this case and demonstrated the principle of comparative advantage—a country will export products that it can produce at low opportunity cost and import products that it would otherwise produce at high opportunity cost. The Ricardian example is developed in more detail. The ratio of resource costs (or labor hour input-output coefficients, the inverse of labor productivities) indicates the opportunity costs or relative prices of the products in each country with no trade. The difference in prices with no trade sets up the opportunity for arbitrage, with each good being exported from the initially low-price country and imported by the initially high-price country. The shift to a free trade equilibrium results in an equilibrium international price. Without information on demand, we cannot say exactly what this price will be, but we do know that it is in the range bordered by the two no-trade price ratios.The chapter uses the Ricardian example to introduce a key analytical device—the production possibility curve, which shows all combinations of outputs of different goods that an economy can produce with full employment of resources and maximum productivity. The resource costs of producing each product in the country and the total amount of labor hours available in the country are used to graph the country's production possibility curve, a straight line whose slope equals the (negative of the) extra (or marginal) cost of additional cloth. The straight line indicates that the marginal or opportunity cost of each good in each country is constant, following Ricardo's assumptions. The slope of this line also indicates the relative price of cloth (the good on the x-axis) with no trade.If free trade results in an equilibrium international price ratio that is strictly between the two no-trade price ratios (because both countries are "large countries"), then each country specializes completely in producing only the good in which it has the comparative advantage. Each trades at the equilibrium international price ratio (along a trade line or price line) to reach its consumption point. Both countries gain from trade. Each is able to consume more of both goods than it consumed with no trade.TipsThis chapter begins the full sweep of the development of thinking about comparative advantage as an explanation of the pattern of trade, starting with absolute advantage, and continuing with comparative advantage according to Ricardo. Most instructors will want to emphasize the continuity of thinking by tying this chapter closely to Chapter 4, which presents Heckscher and Ohlin's insight that comparative advantage can be based on differences in factor proportions and factor endowments. We have divided the discussion of comparative advantage into these two chapters (3 and 4), because students (especially students who find this conceptual material challenging to master) are likely to appreciate that the reading comes in more manageable sizes. This chapter has the first of a series of boxes that “Focus on Labor.” Issues of wages and work conditions are prominent in criticisms of globalization. These boxes should be of major interest to many students, as they take up these issues. The box in this chapter examines the link between (real) wages and productivity. It argues that wages in developing countries are low because labor productivity is low. This is not caused by international trade or foreign exploitation—wages will be low with or without trade. The key to raising wages and living standards is raising productivity, perhaps through education, better health, and better government policies toward labor markets. Problem 9 at the end of the chapter focuses on the calculation of real wages in a Ricardian example.Suggested answers to questions and problems(in the textbook)2. Agree. Imports permit the country to consume more (or do more capital investment usingimported capital goods). Anything that is exported is not available for domesticconsumption (or capital investment). Although this loss is bad, exports are like anecessary evil because exports are how the country pays for the imports that it wants.4. If the countries trade with each other at the relative price of 1 W/C, then shifting only halfway to complete specialization in production would be worse for each country thanshifting to complete specialization. If the United States shifted only half way, then itsnew “trade line” would be parallel to the trade l ine shown in Figure 3.1, and it would start from the point on the ppc that is half way between S0 and S1. While this new trade line would allow the United States to consume at a point that had more consumption than atthe initial S0, the United States could do even better by shifting production all the way to points S1 and consuming along the trade line shown in Figure 3.1. Consuming at a point like C would have even more consumption than consumin g at a point on the new “half-way” trade line. Essentially the same reasoning can be used for the rest of the world, fora new trade line that is parallel to the rest of the world’s trade line shown in Figure 3.1,but that begins at a point on the rest of the world’s ppc that is half way between S0 and S1.6. Using the information on the number of labor hours to make a unit of each product ineach country, you can determine the relative price of cloth in each country with no trade.With no trade, the relative price of cloth is 2 W/C (= 4/2) in the United States, and it is0.4 W/C (= 1/2.5) in the rest of the world. With free trade the equilibrium world priceof cloth must be in the range bounded by these two no-trade prices. So, yes, it ispossible that the free-trade equilibrium relative price of cloth is 1.5 W/C (1.5 is greaterthan 0.4, and less than 2).8. a. M oonited Republic has an absolute advantage in wine—it takes fewer labor hours toproduce a bottle (10<15). Moonited Republic also has an absolute advantage in producing cheese—it takes fewer labor hours to produce a kilo (4<10).b. Moonited Republic has a comparative advantage in cheese. The opportunity cost ofproducing a kilogram of cheese is 0.4 (= 4/10) bottles of wine in Moonited Republic,while the opportunity of a kilo of cheese in Vintland is 0.67 (= 10/15) bottles. Vintlandhas a comparative advantage in wine. The opportunity cost of a bottle of wine is 1.5 kilos of cheese in Vintland, while it is 2.5 kilos in Moonited Republic.c. 1.5312WineVintland N VCheese Wine 20.835N M Cheese Moonited Republicd. When trade is opened, Moonited Republic exports cheese and Vintland exports wine.If the equilibrium free trade price ratio is 1/2 bottle per kilo, Moonited Republic willspecialize completely in producing cheese, and Vintland will specialize completely inproducing wine.e. With free trade Moonited Republic produces 5 (=20/4) million kilos of cheese. If itexports 2 million kilos, then it consumes 3 million kilos. It consumes the 1 million bottles of wine that it imports. With free trade Vintland produces 2 (=30/15) million bottles of wine. If it exports 1 million bottles, then it consumes 1 million bottles. It consumes the 2 million kilos of cheese that it imports.2Wine Cheese Wine2Cheesef. Each country gains from trade. Each is able to consume combined quantities of wine andcheese that are beyond its ability to produce domestically. The free trade consumptionpoint is outside of the production possibility curve.10. If the number of labor hours to make a bushel of wheat is reduced by half to 1 hour, thisreinforces the U.S. comparative advantage in wheat. (In fact, the United States then hasan absolute advantage in wheat.) The United States is still predicted to export wheat and import cloth. If, instead, the number of hours to make a yard of cloth is reduced by half to2 hours, this reduces the U.S. absolute disadvantage in cloth, but it does not change thepattern of comparative advantage. The relative price of cloth is now 1 (=2/2) bushel peryard in the United States with no trade, but this is still higher than the price of 0.67 bushel per yard in the rest of the world. The United States still has a comparative advantage inwheat, so the United States is still predicted to export wheat and import cloth.。