whose ideas about world trade play well with an intellectual audience is the same: the successful books are those that not only do not explicitly discuss mathematical models, they are not even mplicitly based on mathematical reasoning. a book like Robert Reich's The Work of Nations(Reich 1991)not only eschews equations and diagrams, it never even tries to present the idea of comparative advantage informally. In fact, it never uses the phrase"comparative advantage"at all, even to criticize it. As a result, books by authors such as Reich or Thurow do not make humanists uncomfortable. Unavoidably, however, they also give them no sense of the power and importance of economic models in general, or of Ricardos difficult idea in particular. If anything, the message one gets from these books is that in the new economy nineteenth-century concepts no longer apply modelers -as long a&stella ve, be excep tion to the general intellectual aversion to mathematical It might be worth pointing out one syndrome". At one point in Dennett's book he reports a list of the top ten objections raised to Steven Pinker's theories about the evolution of language; one of them is"Natural selection is irrelevant because now we have chaos theory". At about the same time I read this passage I had received a barrage of protests over an article that tried, without explicit mathematics, to walk through some simple models of international trade(Krugman 1994); several of the letters insisted that because of nonlinear dynamics it was impossible to reach any meaningful conclusions from simple models (" Have you ever thought about the implications of increasing returns? You should read the work of Brian Arthur and Paul romer. There are two odd things about the popularity of certain kinds of mathematical modeling among intellectuals who are generally hostile to such models. One is that the preferred models are typically far more difficult and obscure than the standard models in the field The other is that the supposedly heterodox conclusions of these models are often not heterodox at all. to take a theme common to oth evolution and economics the idea that small random events can under certain conditions set in motion a cumulative process of change is the theme both of"peacocks tail"accounts of sexual selection and of external economy accounts of international specialization, both familiar stories that lie well inside the boundaries of academic orthodoxy, stories that can be and are illustrated with Obstfeld(1994). Yet many intellectuals believe that this idea was discovered at Santa Fe an n and simple models in advanced undergraduate textbooks like Maynard Smith(1989 )and Krugma challenges the foundations of both fields The secret to the popularity of certain mathematical modelers, I suspect, is that they are valued precisely because they seem to absolve intellectuals from the need to understand the models that underpin orthodox views. Hardly anyone tries to understand what the Santa Fe theorists are actually saying, it is the pose of opposition to received wisdom, together with the implication that in a complicated world you can't learn anything from simple models anyway, that is valued, because it seems to say that not knowing what's in the textbooks is OK A final note here: there is a new trend among people who don' t like conventional economics, toward what is sometimes called"bionomics". The manifestos of groups like the Bionomics Institute claim that they are developing a new science of economics that abandons the mechanistic approach of the existing field in favor of a model based on ecology and evolution. Speaker of the House Newt Gingrich is reported to be among those who find bionomics appealing). The irony is that neoclassical economics, with its emphasis on modeling the interactions of self-interested individuals, is no more mechanistic than neo-Darwinian evolutionary theory -in fact, the theories are very similar to onewhose ideas about world trade play well with an intellectual audience is the same: the successful books are those that not only do not explicitly discuss mathematical models, they are not even implicitly based on mathematical reasoning. A book like Robert Reich's The Work of Nations (Reich 1991) not only eschews equations and diagrams, it never even tries to present the idea of comparative advantage informally. In fact, it never uses the phrase "comparative advantage" at all, even to criticize it. As a result, books by authors such as Reich or Thurow do not make humanists uncomfortable. Unavoidably, however, they also give them no sense of the power and importance of economic models in general, or of Ricardo's difficult idea in particular. If anything, the message one gets from these books is that in the new economy nineteenth-century concepts no longer apply. It might be worth pointing out one exception to the general intellectual aversion to mathematical models. Intellectuals do reserve, both in evolution and economics, a small pedestal for mathematical modelers -- as long as their models are confusing and seem to refute orthodoxy. Call it the "Santa Fe syndrome". At one point in Dennett's book he reports a list of the top ten objections raised to Steven Pinker's theories about the evolution of language; one of them is "Natural selection is irrelevant, because now we have chaos theory". At about the same time I read this passage I had received a barrage of protests over an article that tried, without explicit mathematics, to walk through some simple models of international trade (Krugman 1994); several of the letters insisted that because of nonlinear dynamics it was impossible to reach any meaningful conclusions from simple models. ("Have you ever thought about the implications of increasing returns? You should read the work of Brian Arthur and Paul Romer.") There are two odd things about the popularity of certain kinds of mathematical modeling among intellectuals who are generally hostile to such models. One is that the preferred models are typically far more difficult and obscure than the standard models in the field. The other is that the supposedly heterodox conclusions of these models are often not heterodox at all. To take a theme common to both evolution and economics: the idea that small random events can under certain conditions set in motion a cumulative process of change is the theme both of "peacock's tail" accounts of sexual selection and of external economy accounts of international specialization, both familiar stories that lie well inside the boundaries of academic orthodoxy, stories that can be and are illustrated with simple models in advanced undergraduate textbooks like Maynard Smith (1989) and Krugman and Obstfeld (1994). Yet many intellectuals believe that this idea was discovered at Santa Fe and challenges the foundations of both fields. The secret to the popularity of certain mathematical modelers, I suspect, is that they are valued precisely because they seem to absolve intellectuals from the need to understand the models that underpin orthodox views. Hardly anyone tries to understand what the Santa Fe theorists are actually saying; it is the pose of opposition to received wisdom, together with the implication that in a complicated world you can't learn anything from simple models anyway, that is valued, because it seems to say that not knowing what's in the textbooks is OK. A final note here: there is a new trend among people who don't like conventional economics, toward what is sometimes called "bionomics". The manifestos of groups like the Bionomics Institute claim that they are developing a new science of economics that abandons the mechanistic approach of the existing field in favor of a model based on ecology and evolution. (Speaker of the House Newt Gingrich is reported to be among those who find bionomics appealing). The irony is that neoclassical economics, with its emphasis on modeling the interactions of self-interested individuals, is no more mechanistic than neo-Darwinian evolutionary theory -- in fact, the theories are very similar to one