Category: Methodology

No Known Upper Bound for Economic Growth

Given the limited state of our knowledge of the process of technological change, we have no way to estimate what the upper bound on the feasible rate of growth for an economy might be. If economists had tried to make a judgment at the end of the 19th century, they would have been correct to argue that there was no historical precedent that could justify the possibility of an increase in the trend rate of growth of income per capita to 1.8% per year. Yet this increase is what we achieved in the 20th century. (p. 226)

Romer, Paul M. “Should the Government Subsidize Supply or Demand in the Market for Scientists and Engineers?” In Innovation Policy and the Economy, vol. 1, Cambridge, MA: MIT Press, 2001, pp. 221-252.

Evidence Matters: The Ivory-Billed Woodpecker

Science doesn’t always work this way, but sometimes it does, and it would be good if it did more often.

The phonex had nothing on the ivory-billed woodpecker.
It is hard to keep track of how many times this near-mythic bird, the largest American woodpecker and a poignant symbol of extinction and disappearing forests, has been lost, and then found. Now it is found again.
Even the most skeptical ornithologists now agree. They say newly presented recordings show that at least two of the birds are living in Arkansas
Richard O. Brum, an ornithologist at Yale University and one of several scientists who had challenged the most recently claimed rediscovery of the ivory bill, said Monday after listening to the tape recordings that he was not “strongly convinced that there is at least a pair of ivory bills out there.”
Mark B. Robbins, an ornithologist at the University of Kansas, who had also been a skeptic, listened to the same recordings with a graduate students and said, “We were absolutely stunned.”

James Gorman and Andrew C. Revkin. “Vindication For a Bird And Its Fans.” New York Times (Tuesday, August 2, 2005): A10.
See also, the earlier: James Gorman. “Woodpecker Flies By and the Critics Soon Follow.” New York Times Section 1 (Sun., July 24, 2005): 1 & 21.

A Modest Proposal

Schools: Save cash
Teaching intelligent design exclusively would allow us to sell off a lot of “scientific” lab equipment and get rid of all of our grossly overpaid “science” teachers.
Imagine the savings if we could hire people who had the common sense to answer that “God did that” to every scientific inquiry. We don’t need to limit intelligent design merely to the question of the origins of humanity, either. It’s such a tidy theory that it can explain just about everything.
It can explain the 250,000 humans killed by the December tsunami. It can explain AIDS. It can explain cancer. It can explain 9/11.
Why bother studying anything at all when we already have the answer?
Dan Mundt, Denison, Iowa

Source: “The Public Pulse.” Omaha World-Herald (Friday, April 12, 2005): 6B.

Debreu on Danger of Over-Mathematization of Economics

From Debreu’s Presidential Address before the American Economic Association:

In the past two decades, economic theory has been carried away further by a seemingly irresistible current that can be explained only partly by the intellectual successes of its mathematization.
Essential to an attempt at a fuller explanation are the values imprinted on an economist by his study of mathematics. When a theorist who has been so typed judges his scholarly work, those values do not play a silent role; they may play a decisive role. The very choice of the questions to which he tries to find answers is influenced by his mathematical background. Thus, the danger is ever present that the part of economics will become secondary, if not marginal, in that judgment. (p. 5)

Debreu, Gerard. “The Mathematization of Economic Theory.” American Economic Review 81, no. 1 (1991): 1-7.

Economics and Physics

Economists have sometimes been accused of physics-envy, but that is an utterly misleading accusation. Anyone who knows modern physics will testify that physicists care about experimental evidence, about bringing their theories into conformity with the experimental evidence, and very little about rigorous theorems and analytical lemmas. What economists really suffer from is mathematics-envy.

Blaug, Mark. “Not Only an Economist: Autobiographical Reflections of a Historian of Economic Thought.” In Reflections of Eminent Economists, edited by Michael Szenberg and Lall Ramrattan, 71-94. Cheltenham, UK: Edward Elgar, 2004, p. 90.

We economists like to think of our science as akin to physics in its mathematical rigor. Quite by accident, while pursuing some research on stochastic processes, I obtained in 1995 a detailed description of the research being done by tenured and tenure-track members of the Harvard University physics department, ranked that same year in a National Research Council survey as the top physics department in the United States. Analysis of the research

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