Methodology of Scientific Research Programmes

Imre Lakatos' theory about how scientists can *rationally* (his emphasis) decide to switch from being a follower of Ptolemy to a follower of Copernicus, or from a "phlogiston person" to someone working on the oxygen theory of combustion.

Most would agree he failed at the "rationally" part, but I think it's a decent account of the psychology and sociology of switching.

This page needs more work before it's ready for outside review.

motivation

Carl Popper had an account of how scientists ought to change their mind. His criterion of falsification held that a scientist should abandon a theory if it predicts something that is refuted by an experiment.

Lakatos observed that Popper would then have to conclude that Isaac Newton would have been a bad scientist. That seems wrong.

> "Theories grow in a sea of anomalies, and counterexamples are merrily ignored" – Imre Lakatos

He also observed that scientists regularly reject crackpot theories that make predictions that have not (yet) been refuted. Does that make Immanuel Velikovsky a better scientist than Newton? That *definitely* seems wrong.

So Popper has himself been refuted. Still, Lakatos, in contrast to his friend Paul Feyerabend , wanted there to be *some* method to distinguish between cranks and scientists. As a philosopher, he wanted that method to be based on rationality rather than psychology. He wanted rules that could be argued for from something like first principles, and that had broad applicability.

the beginning of a research programme

To start with, while Popper focused on individual theories, Lakatos focused on sequences of related theories over time: *research programmes*.

A research program is a collection of theories organized around what Lakatos calls a "**hard core of two, three, four or maximum five postulates**. Consider Newton's theory: its hard core is made up of three laws of dynamics plus his law of gravitation."

A set of postulates starts out inadequate. They typically explain *less* than the programmes they aim to replace. **Counterexamples are shelved to be dealt with later.**

* Newton's theory did not correctly predict the observed movement of the moon, but he did not discard it.

* When Le Verrier discovered the motion of Mercury's perihelion was faster than predicted by Newton, people shrugged and waited for Einstein to explain it.

* Rutherford's model of the atom (mostly empty space, electrons orbiting a nucleus) violated Maxwell's equations, which were believed to be rock solid. They were certainly much more compelling than the new evidence Rutherford's model was intended to explain. But Rutherford's programme essentially said, "We'll figure out how to reconcile with Maxwell later." (The solution was quantized orbits - the "Bohr atom".)

When scientists don't ignore counterexamples, they deal with them by constructing a **protective belt of auxiliary hypotheses** to handle them.

* The Astronomer Royal of England told Newton that observations of the moon refuted his theory of gravitation. To protect it, he invented a new theory of refraction that, together with his laws, did predict the moon's movement. (Sort of - it was never right, because the moon's center of mass isn't at the center of the sphere, which throws off the calculations.)

what's the attraction?

If a new research programme is *worse* than what it intends to explain, why would an ambitious scientist choose to devote a chunk of their career to spinning out the consequences of the postulates?

One reason I could describe as the "wow!" reaction. Scientists are thrilled by dramatic **confirmations of surprising predictions**.

* What convinced scientists of Newton's theory of gravitation? According to Lakatos, it was Edmund Halley's successful prediction (to within a minute) of the return date of the comet that now bears his name.

* What "tipped" scientific opinion toward Einstein's theory of general relativity? The famous experiment in which the bending of light was observed during a solar eclipse. (Interestingly, according to Overbye's Einstein in Love , the observational evidence was actually shaky.)

One reason a scientist might jump to a new research programme is that the old one has ceased to provide what Lakatos calls "novel predictions." The initial *oomph* of the programme has decayed into what Kuhn called "normal science ." Lots of people *like* doing normal science (waves for his wife), but some fraction want more excitement.

ad-hoc protective belts

However, there's another factor, having to do with the nature of the protective belt mentioned above. Colloquially, that would be the difference between "explain" and "explain away."

Consider again Newton and refraction. His theory of optics not only corrects refuting observations to make them match his theory. It is also a theory of its own, makes new predictions, and had some of the new predictions confirmed.

In a way, the observations that refuted Newton's theory of gravitation served to surprisingly confirm his theory of optics, because he developed his theory of optics in *intentional ignorance of the data*. (Per Lakatos, who sometimes exaggerates I fear, the Astronomer Royal offered the details of the lunar observations, but Newton wrote back, saying "Don't bother: if you apply the corrections from my *new* theory of optics, you'll find I was right all along.")

Newton didn't "work backwards" from the observations to his theory, and that added to his credibility. It's that "working backwards" - fitting the protection to the specifics - that distinguishes what Lakatos calls **"ad hoc" protective hypotheses** from the good kind. "[Some proposed counterexample] was never discussed before, but now you can account for this case too by introducing an ad hoc auxiliary hypothesis. Everything can be explained in this way, but there is never any prediction of a corroborated novel fact."

degenerating research programmes