Tuesday, November 24, 2015

Noah, lost at sea

Noah Smith is trying to defend empiricism in economics, but when it comes to empirical facts about the history of science... well, those we can just make up to suit our purposes! And so he writes:

"Our most spectacularly successful leaps of theoretical insight - Newton's Principia, Einstein's relativity stuff, Mendel's theory of inheritance - were all very closely guided by data. The general pattern was that some new measurement technology would be invented - telescopes, plant hybridization experiments, etc. - that would provide some new unexplained data. Then some smart theorists would come up with a new theoretical framework (paradigm?) to explain it, and the new framework would then also explain a bunch of other stuff besides, and so people would switch to the new theory."

Now, I haven't studied the history surrounding Mendel much, so I am not going to comment on it (imagine that: choosing not to write about something because one doesn't know much about it!), except to note that it is a little weird to call plant hybridization experiments a "measurement technology." But with Newton and Einstein, Smith just doesn't know what he is talking about.

First, Newton: the telescope was what spurred on the Principia?! This is a bizarre contention. Perhaps it is true that discovering that Jupiter has moons played some small part in prompting Newton's new physics: I spent a year studying the scientific revolution in graduate school, and subsequently read the top scholarly biography of Newton, but while I don't recall those moons being mentioned as important in Newton's thinking, I won't categorically deny that they might have played a part. However, Kepler's conceptual breakthrough in realizing that the planets have elliptical orbits was much more important to Newton's physics, and it had nothing to do with telescopes. Kepler did rely on improved data collected by Tycho Brahe, but that data could have been handled with epicycles, and the idea of elliptical orbits might have been arrived at without that new data: it was abandoning the idea that celestial objects must move in circles that was the crucial factor here: a new idea.

But what is perhaps even more salient in this regard is that Newton's three laws of motion are not empirically verifiable as a whole: they really are a re-conceptualization of motion, and we need to assume at least one of them to empirically verify the other two.

With Einstein, Smith is on even shakier ground, and it is noteworthy that here he does not even try to suggest what new "measurement technology" prompted Einstein's breakthrough. And as far as "new unexplained data" goes, it is usually the negative result of the Michelson-Morley experiment that empiricists indicate as the impetus for Einstein's special theory of relativity. But Einstein himself told Michael Polanyi that "The Michelson–Morley experiment had no role in the foundation of the theory... the theory of relativity was not founded to explain its outcome at all." In fact, it was Einstein's thought experiment considering what it would be like to travel alongside a beam of light that was the chief driver for developing the "relativity stuff."

So: oops! When it comes to history, scientific "empiricists" appear not to care about "the data" in the least!

PS: Since I do care about the data, I am prompting my friend Thony, who knows much more history of science than I, to correct me here if I have strayed from "the data."


  1. Empiricism comes much more when attempting to validate the theories, so Newton connects the fall of objects and motion of the moon and tides, and Einstein the precession of Mercury, and in general, the ability to explain more on the same principles.

    1. Lord, I am not against empirical data! Empirical facts are vital. Which is why I wish Smith had paid attention to them in the history of science!


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