The Theory of Comparative Advantage
The Theory of Comparative Advantage
In light of Ghana’s absolute advantage in the production of both goods, why should it trade with South Korea? Although Ghana has an absolute advantage in the production of both cocoa and rice, it has a comparative advantage only in the production of cocoa: Ghana can produce 4 times as much cocoa as South Korea, but only 1.5 times as much rice. Ghana is comparatively more efficient at producing cocoa than it is at producing rice.
Without trade the combined production of cocoa will be 12.5 tons (10 tons in Ghana and 2.5 in South Korea), and the combined production of rice will also be 12.5 tons (7.5 tons in Ghana and 5 tons in South Korea). Without trade each country must consume what it produces. By engaging in trade, the two countries can increase their combined production of rice and cocoa, and consumers in both nations can consume more of both goods.
THE GAINS FROM TRADE
Imagine that Ghana exploits its comparative advantage in the production of cocoa to increase its output from 10 tons to 15 tons. This uses up 150 units of resources, leaving the remaining 50 units of resources to use in producing 3.75 tons of rice (point C in Figure 6.2). Meanwhile, South Korea specializes in the production of rice, producing 10 tons. The combined output of both cocoa and rice has now increased. Before specialization, the combined output was 12.5 tons of cocoa and 12.5 tons of rice. Now it is 15 tons of cocoa and 13.75 tons of rice (3.75 tons in Ghana and 10 tons in South Korea). The source of the increase in production is summarized in Table 6.2.
TABLE 6.2 Comparative Advantage and the Gains from Trade
Resources Required to Produce 1 Ton of Cocoa and Rice
Cocoa
Rice
Ghana
10
13.33
South Korea
40
20
Production and Consumption without Trade
Cocoa
Rice
Ghana
10.0
7.5
South Korea
2.5
5.0
Total production
12.5
12.5
Production with Specialization
Cocoa
Rice
Ghana
15.0
3.75
South Korea
0.0
10.0
Total production
15.0
13.75
Consumption After Ghana Trades 6 Tons of Cocoa for 6 Tons of South Korean Rice
Cocoa
Rice
Ghana
11.0
7.75
South Korea
4.0
6.0
Increase in Consumption as a Result of Specialization and Trade
Cocoa
Rice
Ghana
1.0
0.25
South Korea
1.5
1.0
Not only is output higher, but both countries also can now benefit from trade. If Ghana and South Korea swap cocoa and rice on a one-to-one basis, with both countries choosing to exchange 4 tons of their export for 4 tons of the import, both countries are able to consume more cocoa and rice than they could before specialization and trade (see Table 6.2). Thus, if Ghana exchanges 4 tons of cocoa with South Korea for 4 tons of rice, it is still left with 11tons of cocoa, which is 1 ton more than it had before trade. The 4 tons of rice it gets from South Korea in exchange for its 4 tons of cocoa, when added to the 3.75 tons it now produces domestically, leaves it with a total of 7.75 tons of rice, which is 0.25 of a ton more than it had before specialization. Similarly, after swapping 4 tons of rice with Ghana, South Korea still ends up with 6 tons of rice, which is more than it had before specialization. In addition, the 4 tons of cocoa it receives in exchange is 1.5 tons more than it produced before trade. Thus, consumption of cocoa and rice can increase in both countries as a result of specialization and trade.
The basic message of the theory of comparative advantage is that potential world production is greater with unrestricted free trade than it is with restricted trade. Ricardo’s theory suggests that consumers in all nations can consume more if there are no restrictions on trade. This occurs even in countries that lack an absolute advantage in the production of any good. In other words, to an even greater degree than the theory of absolute advantage, the theory of comparative advantage suggests that trade is a positive-sum game in which all countries that participate realize economic gains. As such, this theory provides a strong rationale for encouraging free trade. So powerful is Ricardo’s theory that it remains a major intellectual weapon for those who argue for free trade.
QUALIFICATIONS AND ASSUMPTIONS
LEARNING OBJECTIVE 3
Recognize why many economists believe that unrestricted free trade between nations will raise the economic welfare of countries that participate in a free trade system.
The conclusion that free trade is universally beneficial is a rather bold one to draw from such a simple model. Our simple model includes many unrealistic assumptions:
1. We have assumed a simple world in which there are only two countries and two goods. In the real world, there are many countries and many goods.
2. We have assumed away transportation costs between countries.
3. We have assumed away differences in the prices of resources in different countries. We have said nothing about exchange rates, simply assuming that cocoa and rice could be swapped on a one-to-one basis.
4. We have assumed that resources can move freely from the production of one good to another within a country. In reality, this is not always the case.
5. We have assumed constant returns to scale, that is, that specialization by Ghana or South Korea has no effect on the amount of resources required to produce one ton of cocoa or rice. In reality, both diminishing and increasing returns to specialization exist. The amount of resources required to produce a good might decrease or increase as a nation specializes in production of that good.
6. We have assumed that each country has a fixed stock of resources and that free trade does not change the efficiency with which a country uses its resources. This static assumption makes no allowances for the dynamic changes in a country’s stock of resources and in the efficiency with which the country uses its resources that might result from free trade.
7. We have assumed away the effects of trade on income distribution within a country.
Given these assumptions, can the conclusion that free trade is mutually beneficial be extended to the real world of many countries, many goods, positive transportation costs, volatile exchange rates, immobile domestic resources, nonconstant returns to specialization, and dynamic changes? Although a detailed extension of the theory of comparative advantage is beyond the scope of this book, economists have shown that the basic result derived from our simple model can be generalized to a world composed of many countries producing many different goods.5 Despite the shortcomings of the Ricardian model, research suggests that the basic proposition that countries will export the goods that they are most efficient at producing is borne out by the data.6
However, once all the assumptions are dropped, the case for unrestricted free trade, while still positive, has been argued by some economists associated with the “new trade theory” to lose some of its strength.7 We return to this issue later in this chapter and in the next when we discuss the new trade theory. In a recent and widely discussed analysis, the Nobel Prize–winning economist Paul Samuelson argued that contrary to the standard interpretation, in certain circumstances the theory of comparative advantage predicts that a rich country might actually be worse off by switching to a free trade regime with a poor nation.8 We will consider Samuelson’s critique in the next section.
