Read this section, which covers the underlying meaning of the model of comparative advantage as it is used to analyze how countries as a whole deal with scarce resources.

The U.S. Economy, after Specialization, Will Benefit If It: The Saudi Arabian Economy, after Specialization, Will Benefit If It:
Exports no more than 60 bushels of corn Imports at least 10 bushels of corn
Imports at least 20 barrels of oil Exports less than 60 barrels of oil

Table19.5 The Range of Trades That Benefit Both the United States and Saudi Arabia

The underlying reason why trade benefits both sides is rooted in the concept of opportunity cost, as the following Clear It Up feature explains. If Saudi Arabia wishes to expand domestic production of corn in a world without international trade, then based on its opportunity costs it must give up four barrels of oil for every one additional bushel of corn. If Saudi Arabia could find a way to give up less than four barrels of oil for an additional bushel of corn (or equivalently, to receive more than one bushel of corn for four barrels of oil), it would be better off.

Clear It Up

What are the opportunity costs and gains from trade?

The range of trades that will benefit each country is based on the country's opportunity cost of producing each good. The United States can produce 100 bushels of corn or 50 barrels of oil. For the United States, the opportunity cost of producing one barrel of oil is two bushels of corn. If we divide the numbers above by 50, we get the same ratio: one barrel of oil is equivalent to two bushels of corn, or (100/50 = 2 and 50/50 = 1). In a trade with Saudi Arabia, if the United States is going to give up 100 bushels of corn in exports, it must import at least 50 barrels of oil to be just as well off. Clearly, to gain from trade it needs to be able to gain more than a half barrel of oil for its bushel of corn ­– or why trade at all?

Recall that David Ricardo argued that if each country specializes in its comparative advantage, it will benefit from trade, and total global output will increase. How can we show gains from trade as a result of comparative advantage and specialization? Table 19.6 shows the output assuming that each country specializes in its comparative advantage and produces no other good. This is 100% specialization. Specialization leads to an increase in total world production. (Compare the total world production in Table 19.3 to that in Table 19.6).

Country Quantity produced after 100% specialization ­– Oil (barrels) Quantity produced after 100% specialization ­– Corn (bushels)
Saudi Arabia 100   0
United States   0 100
Total World Production 100 100

Table19.6 How Specialization Expands Output

What if we did not have complete specialization, as in Table 19.6? Would there still be gains from trade? Consider another example, such as when the United States and Saudi Arabia start at C and C', respectively, as shown in Figure 19.2. Consider what occurs when trade is allowed and the United States exports 20 bushels of corn to Saudi Arabia in exchange for 20 barrels of oil.

Figure 19.3 Production Possibilities Frontier in Saudi Arabia Gains from trade of oil can increase only by achieving less from trade of corn. The opposite is true as well: The more gains from trade of corn, the fewer gains from trade of oil.

Starting at point C, which shows Saudi oil production of 60, reduce Saudi Oil domestic oil consumption by 20, since 20 is exported to United States and exchanged for 20 units of corn. This enables Saudi to reach point D, where consumption of oil is now 40 barrels and consumption of corn has increased to 30 (see Figure 19.3). Notice that even without 100% specialization, if the "trading price," in this case 20 barrels of oil for 20 bushels of corn, is greater than the country's opportunity cost, the Saudis will gain from trade. Since the post-trade consumption point D is beyond its production possibility frontier, hence Saudi Arabia has gained from trade.