Paul Krugman, "Ricardo's Difficult Idea" RICARDO'S DIFFICULT IDEA The title of this paper is a play on that of an admirable recent book by the philosopher Daniel Dennett, Darwin's Dangerous Idea: Evolution and the Meanings of Life (1995). Dennett's book is an examination of the reasons why so many intellectuals remain hostile to the idea of evolution through natural selection -- an idea that seems simple and compelling to those who understand it, but about which intelligent people somehow manage to get confused time and time again. The idea of comparative advantage -- with its implication that trade between two nations normally raises the real incomes of both -- is, like evolution via natural selection, a concept that seems simple and compelling to those who understand it. Yet anyone who becomes involved in discussions of international trade beyond the narrow circle of academic economists quickly realizes that it must be, in some sense, a very difficult concept indeed. I am not talking here about the problem of communicating the case for free trade to crudely anti-intellectual opponents, people who simply dislike the idea of ideas. The persistence of that sort of opposition, like the persistence of creationism, is a different sort of question, and requires a different sort of discussion. What I am concerned with here are the views of intellectuals, people who do value ideas, but somehow find this particular idea impossible to grasp. My objective in this essay is to try to explain why intellectuals who are interested in economic issues so consistently balk at the concept of comparative advantage. Why do journalists who have a reputation as deep thinkers about world affairs begin squirming in their seats if you try to explain how trade can lead to mutually beneficial specialization? Why is it virtually impossible to get a discussion of comparative advantage, not only onto newspaper op-ed pages, but even into magazines that cheerfully publish long discussions of the work of Jacques Derrida? Why do policy wonks who will happily watch hundreds of hours of talking heads droning on about the global economy refuse to sit still for the ten minutes or so it takes to explain Ricardo? In this essay, I will try to offer answers to these questions. The first thing I need to do is to make clear how few people really do understand Ricardo's difficult idea -- since the response of many intellectuals, challenged on this point, is to insist that of course they understand the concept, but they regard it as oversimplified or invalid in the modern world. Once this point has been established, I will try to defend the following hypothesis: (i) At the shallowest level, some intellectuals reject comparative advantage simply out of a desire to be intellectually fashionable. Free trade, they are aware, has some sort of iconic status among economists; so, in a culture that always prizes the avant-garde, attacking that icon is seen as a way to seem daring and unconventional. (ii) At a deeper level, comparative advantage is a harder concept than it seems, because like any scientific concept it is actually part of a dense web of linked ideas. A trained economist
looks at the simple Ricardian model and sees a story that can be told in a few minutes; but in fact to tell that story so quickly one must presume that one's audience understands a number of other stories involving how competitive markets work, what determines wages, how the balance of payments adds up, and so on. (iii) At the deepest level, opposition to comparative advantage -- like opposition to the theory of evolution -- reflects the aversion of many intellectuals to an essentially mathematical way of understanding the world. Both comparative advantage and natural selection are ideas grounded, at base, in mathematical models -- simple models that can be stated without actually writing down any equations, but mathematical models all the same. The hostility that both evolutionary
