I Defy the Data!

This is well-recognized issue in philosophy of science, known as the (Pierre) Duhem thesis, that any test of a theory is actually a test of a a conjunction of the theory and the theory of the experiment, and that any resulting disconfirming data might have disconfirmed the theory, the theory of the experiment, or both. The picture turns out to be even more complex, because more than just the theory and the theory of the experiment are tested, but so are background, often nonconscious assumptions, and irrelevant assumptions about statistics. The most detailed technical analysis of theory testing was developed by P. Suppes (1962). Models of data, in Logic, methodology, and philosophy of science (E. Nagel et al., eds., Stanford UP. The proud rejection of data in favor of theory is well attested in history of science, and formed a key part of the neo-Popperian philosophy of Imre Lakatos, e.g. (1970) Criticism and the methology of research programs, in Lakatos & Musgrave (Eds.) Criticism and the growth of knowledge, Cambridge, UP.

Leahey, since I'm not familiar with that line of philosophy, I would ask whether they had the concept of defying data as a bold and insolent act, one which calls for further attention, and which explicitly confesses that the theory and the experimental result are not compatible (so that replication will indeed destroy the theory). This is what I had thought was my innovation. I would not characterize the rejection of data in favor of theory as proud, but rather as sticking your head way out so that someone can easily chop it off.

The post reminds me of one of my favorite scenes from a Hitchcock movie (which I transcribed a while back, knowing it would be useful at some point in the future).

In Hitchcock’s 1938 movie The Lady Vanishes, the heroine Iris Henderson is traveling on a train in the same compartment as an old lady. When the old lady disappears (it later turns out to be connected with a spy ring), Iris scours the train in search of her. She meets a German doctor named Dr. Hartz, who accompanies her on her search for the old lady. But when everyone denies having seen the old lady, Dr. Hartz theorizes that some psychological hallucination must have caused Iris to imagine the old lady’s existence.

But then, finally, Iris finds one woman who admits to having seen the old lady. Iris then confronts Dr. Hartz with this new witness:

“You’ll have to think of a fresh theory now, Doctor.”

"It is not necessary,” Dr. Hartz responds. “My theory was a perfectly good one. The facts were misleading."

I love this idea. It reminds me of a bit of management advice I once heard: knives in the chest, not in the back. For better results, get debate out in the open.

Stuart, the doctor's latter two statements are interesting, but it would seem his first statement is false. He does need to come up with a fresh theory.

I've read that physics journals use a 0.001% standard for statistical significance. Maybe, in the case of "alternative medicine" or "parapsychology" experiments that must rely on unknown physics to work, we should insist on the same standard? ;)

Eliezer, I think you're mistaken on the facts -- most theories take a lot of experimental anomaly before they get thrown out. For example, Kuhn, in Structure of Scientific Revolutions, for example (which I think is a much better work of history than philosophy, but anyway...), gives a marvelous description of "normal science" as just that -- tinkering with the dominant paradigm, fitting new results into it bit by bit, etc.

My experience in engineering fields is quite a bit different. Strange results happened frequently and data was ignored when the circumstances warranted it. Occasionally strange data lead the reseracher to an "A-Ha!" moment but most often the cause was likely due to "operator error" or poor experimental design

The engineers I've worked with were quite savvy about the limitations of their experimental methods and these issues were debated vigorously and openly.

Apparently, things are a bit different in pure science. Or maybe I was just oblivious to 'character assasination' that was happening.

There is more discussion of this post here as part of the Rerunning the Sequences series.

There's a particular field in which you have to do this all the time: Parapsychology, in which people with PhD credentials somehow manage to coax absurd results from apparently impeccable experimental procedures. Daryl Bem is a good example, as is Diane Hennesy Powell.

I can even understand why they think we are the ones being unscientific: I just showed you data! What more do you want? Well, to be honest, we want data that doesn't contradict 200 years of past research in every other scientific field. We know there must be something wrong with your experiment, even if we can pin down what it is (often this comes to light later!); because the result that people can see the future or communicate with the dead just contradicts way too much of what we already knew for us to take it seriously. It's a lot like publishing a proof that 2=1.

Murray Gell-Mann:

Well, here's an example from my own experience. It's fairly dramatic, actually, to have this happen. Three or four of us, in 1957, put forward a partially complete theory of one of these forces, this weak force. And it was in disagreement with seven -- seven, count them, seven experiments. Experiments were all wrong. 

And we published before knowing that, because we figured it was so beautiful, it's gotta be right! The experiments had to be wrong, and they were. Now our friend over there, Albert Einstein, used to pay very little attention when people said, "You know, there's a man with an experiment that seems to disagree with special relativity. DC Miller. What about that?" And he would say, "Aw, that'll go away." (Laughter) 

(Also, the people in the superluminal neutrino fiasco at OPERA did all but defy their own data in the last paragraph of their original arXiv paper.)