Comparative advantage

Origins of the theory

Comparative advantage was first described by Robert Torrens in 1815 in an essay on the corn trade. He concluded that it was to England's advantage to trade various goods with Poland in return for corn, even though it might be possible to produce that corn more cheaply in England than Poland.

However, the theory is usually attributed to David Ricardo who created a systematic explanation in his 1817 book The Principles of Political Economy and Taxation using an example involving England and Portugal. In Portugal it is possible to produce both wine and cloth with less work than it takes in England. However, the relative costs of producing those two goods are different in the two countries. In England it is very hard to produce wine, and only moderately difficult to produce cloth. In Portugal both are easy to produce. Therefore, while it is cheaper to produce cloth in Portugal than England, it is cheaper still for Portugal to produce excess wine, and trade that for English cloth. Conversely, England benefits from this trade because its cost for producing cloth has not changed but it can now get wine at closer to the cost of cloth.

Stanislaw Ulam once challenged Nobel laureate Paul Samuelson to name one theory in all of the social sciences which is both true and nontrivial. Several years later, Samuelson responded with David Ricardo's theory of comparative advantage:

"That it is logically true need not be argued before a mathematician; that it is not trivial is attested by the thousands of important and intelligent men who have never been able to grasp the doctrine for themselves or to believe it after it was explained to them." — Paul Samuelson

Example

Two men land alone in an isolated island. To survive they must undertake a few basic economic activities like water carrying, fishing, cooking and shelter construction and maintenance. The first man is young, strong, and educated and is faster, better, more productive at everything. He has an absolute advantage in all activities. The second man is old, weak, and uneducated. He has an absolute disadvantage in all economic activities. In some activities the difference between the two is great; in others it is small.

Is it in the interest of either of them to work in isolation? No, specialization and exchange (trade) can benefit both of them.

How should they divide the work? According to comparative, not absolute advantage: the young man must spend more time on the tasks in which he is much better and the old man must concentrate on the tasks in which he is only a little worse. Such an arrangement will increase total production and/or reduce total labour. It will make both of them richer.

Specialisation and exchange will not be possible if there is an absolute resource constraint. If, for example, the amount of fresh water available on the island is enough for only one man, then there will be war.

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