Economists arguing about whether economists are scientists, part 1

Those of you who are not regular readers of the economics blogosphere have missed a hugely entertaining spectacle over the summer: prominent and articulate economists have been fighting passionately about whether economics is a science. In doing so, they’ve been attempting to answer some very fundamental questions, like what makes science science, what makes scientists scientists (and thus some economists scientists and others not), when some economists stopped being scientists, what economists think other economists think about what science is, when some economists stopped thinking other economists thought the same thing about what science is, and who insulted whom at a conference in Edgartown, Massachusetts in 1978.

Like introductory econ textbooks, some of the most widely-read econ blogs are written by heavy hitters within the profession, who somehow manage to balance teaching and research loads with astronomical levels of blog output. The most famous is obviously Paul Krugman, Nobel Prize-winning Op-Ed columnist for the New York Times. His blog is called “The Conscience of a Liberal.” There’s also, for instance, Brad DeLong of Berkeley, who blogs at “Grasping Reality with Both Hands”; Tyler Cowen of George Mason at Marginal Revolution; Harvard’s Greg Mankiw (who wrote my intro textbook) has a blog too; and, as of two weeks ago, Larry Summers started a blog (itself blog-worthy news in the econoblogosphere).

Way back at the beginning of the summer, another highly prominent economist and blogger, Paul Romer of NYU, published a short paper called “Mathiness in the Theory of Economic Growth.” Romer drew a distinction between “politics,” a process that maintains divisions, and “science,” one that leads to a broadly shared consensus. Science does so by being formally precise; politics encourages division and thus “words that are evocative or ambiguous.”

The puzzle Romer wanted to solve was why macroeconomic theories of growth had gotten no closer to a consensus in the last twenty years. He suggested that this might have something to do with the fact that much of the field had been infected by “mathiness”—mathematical formalisms that didn’t line up with their verbal claims. Romer cited several prominent and recently-published papers in which the math was sloppy, and inferred from this that nobody checked the math anymore. “Presenting a model is [nowadays] like doing a card trick,” Romer concluded was now the case. “Everybody knows that there will be some sleight of hand.” It was no longer science but politics.

The paper largely, but hardly exclusively, singled out “freshwater” economists for this criticism. “Freshwater” economics is probably what you think of as University of Chicago economics, emphasizing the efficiency of markets and skepticism of government intervention. (The name comes from the fact that, in the 1970s, Chicago-style schools included Carnegie Mellon, the University of Minnesota, and the University of Rochester, all near Great Lakes, whereas, the—again speaking very roughly—economists you think of as Keynesian were concentrated in the “saltwater” schools of economics on the coast. I happen to think this nomenclature is hilarious.) In particular, he pointed the figure at Chicago economist and Nobel laureate Robert Lucas, who he claimed had elided a crucial mathematical point of a model in the verbal presentation of a 2014 paper, a point that would have seriously undermine that paper’s claims had Lucas mentioned it.

The paper, as you can imagine, got other economists’ attention, but Romer—whose Ph.D. is from Chicago—soon claimed to have noticed a disturbing differential in the responses from his colleagues. While the saltwater economists he criticized denied his accusation of sloppy math, they also accepted that, had they been sloppy, they would have been wrong to have done so—wrong because unscientific. But his freshwater friends replied that Lucas and his co-author did nothing wrong in neglecting to mention mathematical details that would weaken their arguments, so long as those details could be found upon close examination. Wasn’t this normal?, they asked, Wasn’t this how all economists behaved? It wasn’t that freshwater and saltwater economists possessed different moral values of right or wrong, Romer suggested: freshwater economists practiced mathiness because that’s what they thought all economists did.

Further conversations with freshwater economists led Romer to conclude that this divide was the result of a “siege mentality [that] encouraged people in this group to ignore criticism from the outside.” Loyalty became more important than “the open criticism that is an essential part of the scientific method.” For the last few decades, in other words, the freshwater vision of the economics profession had been adversarial, not cooperative; politics, not science.


It’s unusual and fascinating to watch scientific practitioners—or, rather, participants in a field which those same participants disagree about whether the field is a science or not—fight about what “science” means. But I ought to have posted about this in August (when there was less to write about). By now the arguments have become both so wide-ranging and technical that they have exceeded my ability to summarize and seriously pushed the limits of a non-economist in understanding them. So I’ll return with another post shortly, tracing out how economists began to make historical arguments about why this division between fresh- and saltwater emerged: watching, in other words, a profession write its own intellectual history in real-time.

Until then I will leave you with a passage I’ve always liked from Thomas Kuhn’s The Structure of Scientific Revolutions. It’s from chapter 12, “Progress through revolutions.” The scientific or non-scientific status of a discipline,” Kuhn writes,

will cease to be a source of concern not when a definition [of science] is found, but when the groups that now doubt their own status achieve consensus about their past and present accomplishments. It may, for example, be significant that economists argue less about whether their field is a science than do practitioners of some other fields of social science. Is that because economists know what science is? Or is it rather economics about which they agree?

2 thoughts on “Economists arguing about whether economists are scientists, part 1

  1. Evan Hepler-Smith

    I’m curious, David – have you come across any discussion that sets up a contrast not between science and politics but between science and law? The latter, it seems to me, is closer than politics to Romer’s take on the freshwater economists: an adversarial method oriented toward achieving consensus on facts and their consequences among parties who frankly stipulate their conflicting interests. Though far be it from me to tell economists how to frame their polemics.



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