It is more realistic to assume diminishing returns for two reasons. First, not all resources are of the same quality. As a country tries to increase its output of a certain good, it is increasingly likely to draw on more marginal resources whose productivity is not as great as those initially employed. The result is that it requires ever more resources to produce an equal increase in output. For example, some land is more productive than other land. As Ghana tries to expand its output of cocoa, it might have to utilize increasingly marginal land that is less fertile than the land it originally used. As yields per acre decline, Ghana must use more land to produce one ton of cocoa.
A second reason for diminishing returns is that different goods use resources in different proportions. For example, imagine that growing cocoa uses more land and less labor than growing rice, and that Ghana tries to transfer resources from rice production to cocoa production. The rice industry will release proportionately too much labor and too little land for efficient cocoa production. To absorb the additional resources of labor and land, the cocoa industry will have to shift toward more labor-intensive methods of production. The effect is that the efficiency with which the cocoa industry uses labor will decline, and returns will diminish.
Diminishing returns show that it is not feasible for a country to specialize to the degree suggested by the simple Ricardian model outlined earlier. Diminishing returns to specialization suggest that the gains from specialization are likely to be exhausted before specialization is complete. In reality, most countries do not specialize, but instead produce a range of goods. However, the theory predicts that it is worthwhile to specialize until that point where the resulting gains from trade are outweighed by diminishing returns. Thus, the basic conclusion that unrestricted free trade is beneficial still holds, although because of diminishing returns, the gains may not be as great as suggested in the constant returns case.
Dynamic Effects and Economic Growth
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 simple comparative advantage model assumed that trade does not change a country’s stock of resources or the efficiency with which it utilizes those resources. This static assumption makes no allowances for the dynamic changes that might result from trade. If we relax this assumption, it becomes apparent that opening an economy to trade is likely to generate dynamic gains of two sorts.9 First, free trade might increase a country’s stock of resources as increased supplies of labor and capital from abroad become available for use within the country. For example, this has been occurring in eastern Europe since the early 1990s, with many Western businesses investing significant capital in the former communist countries.
Second, free trade might also increase the efficiency with which a country uses its resources. Gains in the efficiency of resource utilization could arise from a number of factors. For example, economies of large-scale production might become available as trade expands the size of the total market available to domestic firms. Trade might make better technology from abroad available to domestic firms; better technology can increase labor productivity or the productivity of land. (The so-called green revolution had this effect on agricultural outputs in developing countries.) Also, opening an economy to foreign competition might stimulate domestic producers to look for ways to increase their efficiency. Again, this phenomenon has arguably been occurring in the once-protected markets of eastern Europe, where many former state monopolies have had to increase the efficiency of their operations to survive in the competitive world market.
Dynamic gains in both the stock of a country’s resources and the efficiency with which resources are utilized will cause a country’s PPF to shift outward. This is illustrated in Figure 6.4, where the shift from PPF1 to PPF2 results from the dynamic gains that arise from free trade. As a consequence of this outward shift, the country in Figure 6.4 can produce more of both goods than it did before introduction of free trade. The theory suggests that opening an economy to free trade not only results in static gains of the type discussed earlier, but also results in dynamic gains that stimulate economic growth. If this is so, then one might think that the case for free trade becomes stronger still, and in general it does. However, as noted above, in a recent article one of the leading economic theorists of the twentieth century, Paul Samuelson, argued that in some circumstances, dynamic gains can lead to an outcome that is not so beneficial.