The consensus as an argument

Next week I will travel to the UK, Bristol to be more precise. I will attend the lecture Dogma vs. consensus: Letting the evidence speak on climate change presented by John Cook. He will discuss his research (the consensus project) and more broader the “scientific consensus”.

The last 11 posts I was lamenting about the pickle Belgium is in next winter, energy wise, now it is time for a change of topic. Next few posts will be about the consensus, exploring various sides of it prior to attending this lecture.

The first question I want to look at: does consensus has a place in science? As far as I know, consensus has nothing to do with the scientific method. Truth isn’t decided by show of hands. If history teaches us anything it is that scientists agree with each other for numerous reasons, not necessarily good ones. Sometimes those who were right were in the minority. Just remember Harlen Bretz, Alfred Wegener, Albert Einstein, Barry Marshall & Robin Warren, to name just a few of the better known ones. There are probably numerous other scientists that were forgotten or those who swallowed their objections.

It doesn’t necessarily mean that the skeptics voices have to be compared with for example an Einstein or that those in the minority are always right. These examples are given just to indicate that a consensus is not a valid scientific argument. One can not determine anything from looking at a theory from a consensus position or from a minority position. Neither of the two tells us something about the strength of the argument(s) used. A widespread acceptance of a theory is not evidence of it being correct.

That was of course not how I thought about it when I was still a believer. At that time I assumed that when scientists agree about something, then it should be important to listen. The experts, who have this as their job, should know a thing or two what they are talking about, you know.

In a way I still believe this, but my expectations became a bit more realistic. I still believe that when scientists agree with each other that it could be important to listen. Could, not should.

Not all sciences are born equal. If those in the majority say gravity exists, I would have no problem agreeing with that consensus. But climate science is a different beast altogether. The material they work with is not so certain, datasets contain scarce data before the 1980s, forcings and feedbacks are numerous, the system they study is very complex, there are many experts that are involved. Plus the science is politicized. In that light it is very suspicious that so many scientists would agree with each other. Yet when we hear scientists in the media, they try to tell us that they are so damn certain about these intrinsically uncertain things and the debate is over. Something is not right here.

If there was high quality data over a century, the system was not so complex, not so dependent on numerous expertises, the science not so politicized, not so polarized, not so impregnated with the compulsion of saving the world and not so dependent on mathematical models, then I would have no problem at all with that consensus.

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