Why does scientific discourse gets vicious?

The other day at dinner, we were remembering a period of 5 to 10 years, during which a few (highly respected, highly influential, extremely prolific, and for good reasons) researchers in our field wrote a series of vitriolic papers mostly directed at one another. They were not just mean-spirited. They were downright nasty. The “debate” spilled over in books, conferences, and (ultimately) shaped a good part of the literature up to this day.

Why?

If science is objective and dispassionate, the debate around data should never get vicious — because either a statement is supported by evidence, or it is not. Since science is neither objective nor dispassionate (because scientists are neither of these things), nasty debates are expected to happen. The debate exists because people have conflicting viewpoints about the evidence that is available; it gets vicious because people care, and sometimes we express this in objectively terrible ways. But besides the usual recipe for having a vicious battle (people with strong opinion and large egos), we went to discuss the other conditions for a debate that spirals out of control.

When?

Not enough data; this was the first thing we thought about. It — sort of — makes sense, too. When a new question emerges, there is usually a little bit of empirical evidence available. This can be explained in different ways, and it makes sense that different group of people will advance different hypotheses. This multiplicity of hypotheses is — in my mind — a good thing. It avoids that we confine ourselves to a single view, and it helps designing tests of the various theories: how can we design analyses that would give information about the validity of the different explanations, at once? With the accumulation of data, the propositions that make a good job at prediction should gain support, and the others should be abandoned. In short, vicious scientific debate is the sign of a young field, in which there are more ideas than there are cold, hard data.

Really?

I was mostly satisfied with this idea, for the next few days. Then I realized one thing. In this particular example, the accumulation of data over the next 10 years did nothing to calm the discussion. It stopped because people grew bored, but a consensus never really appeared. Then I remembered this line by Imre Lakatos:

Scientists have a thick skin. They do not abandon a theory merely because facts contradict it.

This, is pretty much what happened. The evidence continued to pile-up, and it supported neither theory entirely. The following years saw new models to reconcile both with data. The new evidence revealed that none of these proposals were entirely or universally adequate at predicting the data. It took 10 years for someone to publish a synthesis that said, in short “This is complicated, and the more we know, the less we know”.

This is an interesting story (not only because it shaped a lot of empirical and theoretical research, either directly or not). This debate went on so strongly, and for so many years, because neither side was able to get confirmation in data. This is an alternative hypothesis we have to consider — sometimes, the fact that the debate gets vicious is a sign that none of us are even close to the solution.