Thursday, December 24, 2009

Economics Is As Much A Science As Physics?

It may be Christmas Eve, but I'm not in a forgiving mood. There is a quote from some clueless "philosopher" who thinks that economics is as much a science as physics!

I asked [philosopher] Nelson Goodman this question once, and Nelson Goodman said economics is as much of a science as physics. I said, well, how could that be? He said: Physics can explain how a leaf falls from a tree and everything that happens to it, but it can't tell you where the leaf's going to land. Economics is the same.

That's utterly stupid. How do you think we were able to send things out in outer space if we don't know where it is going to "land"? Being able to "explain" and describe the dynamics of that leaf INCLUDES the ability to predict what will happen. That's how you know your electronics will work, because we have predicted with great accuracy how the mechanism within your semiconductors will behave in the future.

But the stupidity doesn't end there...

Yes, absolutely right. I use that all the time. The parts of physics that are exact are the parts of physics that are exact. The parts that are inexact are vastly greater. Sensible scientists don't waste their time pushing against doors that endlessly will not give. They are opportunistic and go where they can, but there are pitfalls in that. It's like the drunk who is looking for his keys under the lamplight in the street, but he wasn't near the lamplight. He said, yes, but that's the only place I can see anything, therefore I'm looking here.

That makes no sense, especially when this person doesn't illustrate such accusation with an example. The whole idea of doing science is to go into places where we either have little knowledge in, or in which our current understanding just doesn't work. That's exactly an example of looking where the lamplight isn't there!

People who have never worked in science, or physics in particular, and then try to make generalized characterization of the field, simply reveal their complete ignorance. And when you start with a foundation based on faulty knowledge, you end up with absurd conclusion, such as equating economics to be as much of a science as physics.



Peter said...

This quote from Nelson Goodman to some extent invokes Otto Neurath's "In some cases a physicist is a worse prophet than a [behaviourist psychologist], as when he is supposed to specify where in Saint Stephen's Square a thousand dollar bill swept away by the wind will land, whereas a [behaviourist] can specify the result of a conditioning experiment rather accurately" (originally 1933, "United Science and Psychology"; this is as cited on page 27 of Nancy Cartwright's "The Dappled World: A Study of the Boundaries of Science", which is a book that I suppose would make you cross). This is a relatively famous example in Philosophy of Science. The substitution of a leaf for a thousand dollar bill makes it rather sadly less visceral.

Applied to your counter-example, Neurath challenges Physicists to predict precisely when a particular individual electronic gadget will break, whether because of a cosmic ray or because of being dropped. Classical physics never tried to do this, at least since Poincar\'e, although noting the ambition of Laplace's demon, because of an inability to determine initial conditions with sufficient accuracy, and modern physics does not try to do this because of the irreducible indeterminism of quantum theory.

The statistics of when individuals in an ensemble of gadgets will break are accessible to description and prediction by physics (we could, for example, estimate how often background radiation or other physics would affect a given type of gadget, and the chance that the consequences would be terminal), but the statistics of economic events could perhaps be claimed to be as accessible to description and prediction by economics.

There are, as you say, questions of whether economics can give a causal explanation of anything, however in the age of quantum theory it is moderately tendentious to claim that physics gives a causal explanation.

A generous reading of the Goodman quote might suppose that Goodman would only make such a claim when arguing at a level of extreme, non-numeric abstraction. I was going to write that economics cannot make many predictions to 10 significant figures, but looked at the display of the US national debt at, for example,, which claims a spurious 14 digit accuracy. The causes for the steady increase of the national debt are documented in various ways (but I can imagine all sorts of ways in which this example might be ripped apart as not at all as satisfying as the sort of causal explanation that quantum theory gives).

Anonymous said...

I once argued with an economist who claimed his field could make accurate forecasts of economic trends, climates, catastrophes, and so forth. I asked him to provide some examples. He said "What do you mean, examples?"

I said "You know: documented instances where economic theory predicted something important about the economy."

"Huh? I don't have anything like that."

sandycharm said...

The economist pissed me off. Physics is the first discipline that developed as a science. Chemistry, Biology, Psychology..came later. The scientific methodology we have today is to a large extent shaped by developments in physics.
Economics is just a wannbe physics.

Gordon said...

Philosophy is about as interesting as a sack of wet noodles, and about as useful as a blown out tire.

Quantum Mechanics, The Standard Model, and Relativity stand alongside Evolution as the most tested scientific theories of all time. So to claim that physics makes no predictions is outright false.