But is Ricardo the author of the famous pages in his "Principles of Political Economy"? Some have argued that James Mill is the true author.
In a footnote on page 132 of the fifth edition of his "Economic Theory in Retrospect" Mark Blaug writes
Ironically enough, it is now been shown that the famous pages on comparative advantage in the chapter on foreign trade were almost certainly written by James Mill. Moreover, Ricardo's own conception of foreign trade never effectively went beyond the idea of absolute advantage; in short, he does not deserve the credit he has been given for the theory of comparative advantage.The basis for Blaug's claim is the paper, by William O. Thweatt, "James Mill and the Early Development of Comparative Advantage", History of Political Economy 8 (Summer 1976) 207-34.
A quick look at Douglas Irwin's book "Against the Trade: An Intellectual History of Free Trade" gives rise to another footnote, from page 91, which reads,
Thweatt's case is plausible because Mill worked closely with Ricardo on the Principles and commented extensively on drafts. Inconclusive evidence against his interpretation comes in a letter from Mill to Ricardo in which he states: "... that it may be good for a country to import commodities from a country where the production of those same commodities cost more, than it would cost at home: that a change in manufacturing sill in one country, produces a new distribution of the precious metals, are new propositions of the highest importance, and which you fully prove." See David Ricardo (1952, 7: 99). Further, in his article on colonies Mill also credits Ricardo with the theory.It has also argued that Mill explained the idea of comparative advantage better in his "Elements of Political Economy", published after Ricardo's "Principles".
But whoever wrote about comparative advantage Ricardo's book is worth celebrating. So joint Irwin and many other economists in raising a glass of wine, from a country of your choice, to David Ricardo!
Updated: In the comments section to this posting Jorge Morales Meoqui writes,
The authorship debate about comparative advantage has mostly revolved about the relative merits of Ricardo's statement in the Principles and Robert Torrens’ statement in Essay on the External Corn Trade (1815). James Mill never claimed merit for it, and in the letter to his friend Ricardo he indicated unequivocally who should be credited for the insight.For more on Morales Meoqui's work on the comparative advantage debate see here.