science commentary

What is the role of consensus in science?

Consensus is a social phenomenon. It is an appeal to authority, which has no place in science

by T.J. Nelson

What is the role of consensus in science?

W hat is the role of consensus in science? The answer is simple: It has no role whatsoever. ‘Consensus’ is neither part of the scientific method nor a goal in science. It is a tool used by non-scientists searching for trends in the thinking among scientists. When used as a tool for understanding, it can be harmless. But when it's used to manufacture a false climate of authority, it can be very harmful indeed.

The myth that science seeks to achieve a consensus has been debunked many times. But activists continually revive it. One article at Ars Technica, a computer news site that sometimes talks about global warming, is typical. They point out that we have agreed-upon criteria for determining statistical significance. Once a finding has accumulated enough supporting evidence, they claim, it is considered ‘settled,’ and need not be re-investigated.

This is not true. No scientist uses the phrase ‘settled science’ to support their conclusions. If they did, their papers would be ignored and they'd be laughed off the podium. Consensus implies cognitive closure, which is sternly resisted in science.

Yes, we use standards and conventions, just like ordinary mortal humans. When we write in English, we use the same rules of syntax. We use the same type of mathematics, the same counting system, and the same definition of the gram. In a given country, we all agree to drive on the same side of the road. One might reasonably call this a consensus. But it would be sloppy reasoning—a form of equivocation—to imply that any of this is the method by which science builds knowledge. Either the activists are unfamiliar with how science works, or they are making a basic error of logic, or they are being disingenuous.

Consensus is a social phenomenon, not a part of science. Scientists are human, and they're susceptible to human weakness, and the urge to conform is one of them. When they succumb to it, science suffers.

One example is the question of whether HIV is the causal agent of AIDS. As a practical matter, if introducing a virus into a patient causes the disease and eliminating the virus cures it, that is good enough for most scientists to consider the subject no longer worth studying. Science tries to solve problems, and if the problem goes away, scientists turn to something else that is more pressing and interesting.

A better example is stomach ulcers. Most scientists considered ulcers to be uninteresting. They thought, as many people did, that they were caused by stress. That idea turned out to be incorrect, and the two people who discovered it received a well-deserved Nobel prize.

But this most emphatically does not mean that consensus played any role, either before the discovery or afterward. Even if the opinions of physicians and scientists had been measured, and some universally agreed threshold, say 50% + 1, or maybe 95%, of their opinions had been reached, it still would have no bearing on whether the stress theory was true. If consensus was a meaningful criterion, Robin Warren and Barry Marshall would not have investigated the bacteria hypothesis, and they might never have discovered the true cause.

No scientist worth his or her salt gives a flying frak about what everyone else thinks. (Funding agencies unfortunately do, and that's a longstanding problem).

So what about the claim made by the climate activists, that a “97% consensus” exists among climate scientists? Simply speaking, this is a manufactured number, created by another well-known problem: publication bias. It is very difficult to get a paper published that shows a negative result. Very often, scientists don't even try, because it's a waste of effort.

(It's also manufactured in another way. As someone just pointed out to me, even my skeptical article pointing out the scientific flaws in AGW would be included among the 97%.)

The concept of consensus does not come from scientists, but from news reporters and others who are searching for a shared viewpoint so they can write a story and appear credible. They want to make a generalization, so they say that a ‘consensus’ exists. This might sound like a reasonable thing for a non-scientist to do. But the activists are trying to change public opinion by manufacturing a consensus that suits their political goals.

I have been a professional research scientist for over 30 years, first at a large, well-known place in Bethesda, Maryland, which has thousands of scientists, and later at a nonprofit research institute. I have read literally thousands of research papers and published nearly a hundred in peer-reviewed journals. I have listened to hundreds of seminars and had countless conversations with fellow scientists. Not once did any of them ever use the term ‘consensus’ to promote the accuracy of their results.

Do scientists ever use the term? Of course. A grep of the 2106 scientific reprints currently on my computer yields 205 instances of the term consensus. Almost all of them are molecular biology papers, where someone is comparing multiple DNA or protein sequences and obtaining a ‘consensus sequence.’ This simply means that most of the sequences contain a particular base or amino acid at a particular location. I have never heard it used by any scientist to mean that we should accept a conclusion based on consensus.

Consensus, as used that way, is an appeal to authority. It is intended to silence skeptics. But as much as some would like it to be true, authority has no place in science. In fact, I will go out on a limb and say that using the term around real scientists marks one as an outsider or neophyte. In general, only non-scientists use this term.

Climate activists, though, use it all the time. Their goal is to stampede people into accepting a massive transformation of society. It may or may not be necessary to do this. But no one should ignore the cost. If we do as the climate activists insist we must, we need to accept the fact that there is a high probability that it will leave our civilization in ruins.

Here's another example. It is sometimes claimed that there was a ‘consensus’ among biologists that cholesterol and salt are harmful and should be greatly reduced in our diet. To the public, the US government's about-face on cholesterol came as a shock, with some asking why scientists did not question the guidelines earlier.

It might come as a surprise to learn, then, that they have long been subjects of vigorous debate. Although the government made specific recommendations, there was never any ‘consensus’ among scientists about cholesterol. Some of my neuroscience colleagues are quite emphatic that statins, drugs that inhibit the synthesis of cholesterol in the body, are dangerous drugs. The brain needs cholesterol to function; cholesterol bound to a protein called apolipoprotein E is an important signal for synaptogenesis, a process that is intimately tied to learning and memory. The original studies used rabbits, which are herbivores and the worst possible species to use to study dietary cholesterol—unless your goal is to make them sick.

Most of my colleagues advise me to remain silent. Science is self-correcting, they say, and the truth, whatever it is, will ultimately prevail. The number of ways science can be misinterpreted is infinite. But I have seen what has happened to other fields: history, psychology, sociology. Cool heads remained silent there, and the field was partially taken over by political activists, and its credibility was compromised. There is no reason to believe that science is immune.

The statin Lipitor is the biggest-selling drug in history. As in climate, billions of dollars are at stake. So we keep our non-consensual opinions to ourselves until we can come up with compelling evidence. Sadly, that's what scientists have to do these days to stay employed and to stay out of court.

And that is one thing that there is a consensus about. But even climate activists know there's a difference between a court of law and a laboratory. If you're confused, it's simple: the laboratory is the one where nobody ever talks about consensus.

See also:


What is the value of computer modeling?
If mathematical models are done badly, they will discredit an entire branch of science. It's happened before.


The Precautionary Principle: Common Sense or Sloppy Thinking?
Contrary to what has been claimed, the precautionary principle is not commonly followed by responsible public officials, scientists, or law courts, and it should not be adopted as an element in decision-making.


Cold facts about global warming
Even though global warming has become mostly an academic concern now that the climate has moved into a cooling phase, it's still important to understand what is and is not factual about the climate.


Rethinking ozone
Has the Montreal Protocol actually done anything? Nearly 30 years after CFCs were banned, something is not adding up.


On the Internet, no one can tell whether you're a dolphin or a porpoise
feb 11, 2015; updated feb 21, 2015

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