What is Scientific Consensus?

 Do a Google search for the term “global warming consensus” & you’ll find >24K links (& >19M results without the quotations marks). The first link for “global warming consensus” is to this NASA webpage with the title “Scientific Consensus” & the following statement:

"Multiple studies published in peer-reviewed scientific journals show that 97% or more of actively publishing climate scientists agree: Climate-warming trends over the past century are due to human activities. In addition, most of the leading scientific organizations worldwide have issued public statements endorsing this position."

Here’s what Michael Crichton, M.D. had to say about 'scientific consensus' back in 2003 when he gave a lecture at the California Institute of Technology:   

"I want to pause here & talk about this notion of consensus, & the rise of what has been called consensus science. I regard consensus science as an extremely pernicious development that ought to be stopped cold in its tracks. Historically, the claim of consensus has been the first refuge of scoundrels; it is a way to avoid debate by claiming that the matter is already settled. Whenever you hear the consensus of scientists agrees on something or other, reach for your wallet, because you’re being had.

Let’s be clear: the work of science has nothing whatever to do with consensus. Consensus is the business of politics. Science, on the contrary, requires only one investigator who happens to be right, which means that he or she has results that are verifiable by reference to the real world. In science consensus is irrelevant. What is relevant is reproducible results. The greatest scientists in history are great precisely because they broke with the consensus. There is no such thing as consensus science. If it’s consensus, it isn’t science. If it’s science, it isn’t consensus. Period.

In addition, let me remind you that the track record of the consensus is nothing to be proud of. Let’s review a few cases. In past centuries, the greatest killer of women was fever following childbirth. One woman in 6 died of this fever. In 1795, Alexander Gordon suggested that the fevers were infectious processes, & he was able to cure them. The consensus said no.

In 1843, Oliver Wendell Holmes claimed puerperal fever was contagious, & presented compelling evidence. The consensus said no.

In 1849, Semmelweiss demonstrated that sanitary techniques virtually eliminated puerperal fever in hospitals under his management. The consensus said he was a Jew, ignored him, & dismissed him from his post. There was in fact no agreement on puerperal fever until the start of the 20th century. Thus the consensus took 125 years to arrive at the right conclusion despite the efforts of the prominent 'skeptics' around the world, skeptics who were demeaned & ignored. And despite the constant ongoing deaths of women.

There is no shortage of other examples. In the 1920s in America, tens of thousands of people, mostly poor, were dying of a disease called pellagra. The consensus of scientists said it was infectious, & what was necessary was to find the 'pellagra germ.' The US government asked a brilliant young investigator, Joseph Goldberger, to find the cause. Goldberger concluded that diet was the crucial factor. The consensus remained wedded to the germ theory.

Goldberger demonstrated that he could induce the disease through diet. He demonstrated that the disease was not infectious, by injecting the blood of a pellagra patient into himself & his assistant. They & other volunteers swabbed their noses with swabs from pellagra patients, & swallowed capsules containing scabs from pellagra rashes. Nobody contracted pellagra.

The consensus continued to disagree with him. There was, in addition, a social factor--Southern states disliked the idea of poor diet as the cause, because it meant that social reform was required. They continued to deny it until the 1930s. Result--despite an epidemic, the consensus took years to see the light.

Probably every schoolchild notices that South America & Africa seem to fit together rather snugly, & Alfred Wegener proposed, in 1912, that the continents had in fact drifted apart. The consensus sneered at continental drift for 50 years. The theory was most vigorously denied by the great names of geology--until 1961, when it began to be noticed that the sea floors were spreading. The result: it took the consensus 50 years to acknowledge what any schoolchild sees.

And shall we go on? The examples can be multiplied endlessly. Jenner & smallpox, Pasteur & germ theory. Saccharine, margarine, repressed memory, fiber & colon cancer, hormone replacement therapy. The list of consensus errors goes on & on.

Finally, I would remind you to notice where the claim of consensus is invoked. Consensus is invoked only in situations where the science is not solid enough. Nobody says the consensus of scientists agrees that E=mc2. Nobody says the consensus is that the sun is 93M miles away. It would never occur to anyone to speak that way.

The notion of a monolithic 'science,' meaning what scientists say, is pernicious, & the notion of 'scientific consensus' actively so. The route to knowledge is transparency in disagreement & openness in debate. The route to truth is the pluralist expression of conflicting views in which, often not as quickly as we might like, good ideas drive out bad. There is no room in this process for any notion of 'scientific consensus'!"

Related paragraph: See, what he is parroting is not science _per se_, rather: *"scientism"*:

"the opinion that science & the scientific method are the only way to render truth about reality. Some scholars have adopted it as a pejorative term with the meaning 'an exaggerated trust in the efficacy of the methods of natural science applied to all areas of investigation (as in philosophy, the social sciences, & the humanities).' Given its sweeping claims, it soon came under heavy scrutiny. Karl Popper pointed out that few statements in science can actually be completely verified. However, a single observation has the potential to invalidate a hypothesis, & even an entire theory. What counts as an observation, how to construct an experiment, & what data you think your instruments are collecting—all require an interpretive theoretical framework, which are based on one's worldview assumptions. This realization does not deal a death-blow to the practice of science, but it does undermine the positivist claim that science rests entirely on facts, & is thus an indisputable foundation for knowledge."