When to Doubt a Scientific Consensus
Anyone who has studied the history of science knows that scientists are not immune to the non-rational dynamics of the herd.
A December 18, 2009 Washington Post poll, released on the final day of the ill-fated Copenhagen climate summit, reported “four in ten Americans now saying that they place little or no trust in what scientists have to say about the environment.” This was the month the tide turned in public perceptions of climate change. Several recent polls have found “climate change” skepticism rising faster than sea levels on Planet Algore (not to be confused with Planet Earth, where sea levels remain relatively stable).
Many of the doubt-inducing climate scientists and their media acolytes attribute this rising skepticism to the stupidity of Americans, philistines unable to appreciate that there is “a scientific consensus on climate change.” One of the benefits of the 2009 Climategate scandal, which revealed leading climate scientists manipulating data, methods and peer review to exaggerate the evidence of significant global warming, may be to permanently deflate the rhetorical value of the phrase “scientific consensus.”
But since Pope Francis has invoked a scientific “consensus” in his new encyclical, Laudato Si, it may be time to revisit this issue.
Even without the 2009 scandal, the very idea of scientific consensus should give us pause. “Consensus,” according to Merriam-Webster, means both “general agreement” and “group solidarity in sentiment and belief.” That pretty much sums up the dilemma. We want to know whether a scientific consensus is based on solid evidence and sound reasoning, or social pressure and groupthink.
Anyone who has studied the history of science knows that scientists are not immune to the non-rational dynamics of the herd. Many false ideas enjoyed consensus opinion at one time. Indeed, the “power of the paradigm” often shapes the thinking of scientists so strongly that they become unable to accurately summarize, let alone evaluate, radical alternatives. Question the paradigm, and some respond with dogmatic fanaticism.
We shouldn’t, of course, forget the other side of the coin. There are always cranks and conspiracy theorists. No matter how well founded a scientific consensus, there’s someone somewhere — easily accessible online — who thinks it’s all hokum. Sometimes these folks turn out to be right. But often, they’re just cranks whose counsel is best disregarded.
So what’s a non-scientist citizen, without the time to study the scientific details, to do? How is the ordinary citizen to distinguish, as Andrew Coyne puts it, “between genuine authority and mere received wisdom? Conversely, how do we tell crankish imperviousness to evidence from legitimate skepticism?” Are we obligated to trust whatever we’re told is based on a scientific consensus unless we can study the science ourselves? When can you doubt a consensus? When should you doubt it?
Your best bet is to look at the process that produced, maintains and communicates the ostensible consensus. I don’t know of any exhaustive list of signs of suspicion, but, using climate change as a test study, I propose this checklist as a rough-and-ready list of signs for when to consider doubting a scientific “consensus,” whatever the subject. One of these signs may be enough to give pause. If they start to pile up, then it’s wise to be suspicious.
(1) When different claims get bundled together
Usually, in scientific disputes, there is more than one claim at issue. With global warming, there’s the claim that our planet, on average, is getting warmer. There’s also the claim that human emissions are the main cause of it, that it’s going to be catastrophic, and that we have to transform civilization to deal with it. These are all different assertions with different bases of evidence. Evidence for warming, for instance, isn’t evidence for the cause of that warming. All the polar bears could drown, the glaciers melt, the sea levels rise 20 feet and Newfoundland become a popular place to tan, and that wouldn’t tell us a thing about what caused the warming. This is a matter of logic, not scientific evidence. The effect is not the same as the cause.
There’s a lot more agreement about (1) a modest warming trend since about 1850 than there is about (2) the cause of that trend. There’s even less agreement about (3) the dangers of that trend, or of (4) what to do about it. But these four propositions are frequently bundled together, so that if you doubt one, you’re labeled a climate change “skeptic” or “denier.” That’s just plain intellectually dishonest. When well-established claims are fused with separate, more controversial claims, and the entire conglomeration is covered with the label “consensus,” you have reason for doubt.
(2) When ad hominem attacks against dissenters predominate
Personal attacks are common in any dispute simply because we’re human. It’s easier to insult than to the follow the thread of an argument. And just because someone makes an ad hominem argument, it doesn’t mean that their conclusion is wrong. But when the personal attacks are the first out of the gate, and when they seem to be growing in intensity and frequency, don your skeptic’s cap and look more closely at the evidence.
When it comes to climate change, ad hominems are all but ubiquitous. They are even smuggled into the way the debate is described. The common label “denier” is one example. Without actually making the argument, this label is supposed to call to mind the assertion of the “great climate scientist” Ellen Goodman: “I would like to say we’re at a point where global warming is impossible to deny. Let’s just say that global warming deniers are now on a par with Holocaust deniers.”
There’s an old legal proverb: If you have the facts on your side, argue the facts. If you have the law on your side, argue the law. If you have neither, attack the witness. When proponents of a scientific consensus lead with an attack on the witness, rather than on the arguments and evidence, be suspicious.
(3) When scientists are pressured to toe the party line
The famous Lysenko affair in the former Soviet Union is often cited as an example of politics trumping good science. It’s a good example, but it’s often used to imply that such a thing could only happen in a totalitarian culture, that is, when all-powerful elites can control the flow of information. But this misses the almost equally powerful conspiracy of agreement, in which interlocking assumptions and interests combine to give the appearance of objectivity where none exists. For propaganda purposes, this voluntary conspiracy is even more powerful than a literal conspiracy by a dictatorial power, precisely because it looks like people have come to their position by a fair and independent evaluation of the evidence.
Tenure, job promotions, government grants, media accolades, social respectability, Wikipedia entries, and vanity can do what gulags do, only more subtly. Alexis de Tocqueville warned of the power of the majority in American society to erect “formidable barriers around the liberty of opinion; within these barriers an author may write what he pleases, but woe to him if he goes beyond them.” He could have been writing about climate science.
Climategate and the dishonorable response to its revelations by some official scientific bodies show that scientists are under pressure to toe the orthodox party line on climate change and receive many benefits for doing so. That’s another reason for suspicion.
(4) When publishing and peer review in the discipline is cliquish
Though it has its limits, the peer-review process is meant to provide checks and balances, to weed out bad and misleading work, and to bring some measure of objectivity to scientific research. At its best, it can do that. But when the same few people review and approve each other’s work, you invariably get conflicts of interest. This weakens the case for the supposed consensus, and becomes, instead, another reason to be suspicious. Nerds who follow the climate debate blogosphere have known for years about the cliquish nature of publishing and peer review in climate science (see here, for example).
(5) When dissenting opinions are excluded from the relevant peer-reviewed literature not because of weak evidence or bad arguments but as part of a strategy to marginalize dissent
Besides mere cliquishness, the “peer review” process in climate science has, in some cases, been consciously, deliberately subverted to prevent dissenting views from being published. Again, denizens of the climate blogosphere have known about these problems for years, but Climategate revealed some of the gory details for the broader public. And again, this gives the lay public a reason to doubt the consensus.
(6) When the actual peer-reviewed literature is misrepresented
Because of the rhetorical force of the idea of peer review, there’s the temptation to misrepresent it. We’ve been told for years that the peer-reviewed literature is virtually unanimous in its support for human-induced climate change. In Science, Naomi Oreskes even produced a “study” of the relevant literature supposedly showing “The Scientific Consensus on Climate Change.” In fact, there are plenty of dissenting papers in the literature, and this despite mounting evidence that the peer-review deck was stacked against them. The Climategate scandal also underscored this: The climate scientists at the center of the controversy complained in their emails about dissenting papers that managed to survive the peer-review booby traps they helped maintain, and fantasized about torpedoing a respected climate science journal with the temerity to publish a dissenting article.
(7) When consensus is declared hurriedly or before it even exists
A well-rooted scientific consensus, like a mature oak, usually needs time to emerge. Scientists around the world have to do research, publish articles, read about other research, repeat experiments (where possible), have open debates, make their data and methods available, evaluate arguments, look at the trends, and so forth, before they eventually come to agreement. When scientists rush to declare a consensus, particularly when they claim a consensus that has yet to form, this should give any reasonable person pause.
In 1992, former Vice President Al Gore reassured his listeners, “Only an insignificant fraction of scientists deny the global warming crisis. The time for debate is over. The science is settled.” In the real 1992, however, Gallup “reported that 53% of scientists actively involved in global climate research did not believe global warming had occurred; 30% weren’t sure; and only 17% believed global warming had begun. Even a Greenpeace poll showed 47% of climatologists didn’t think a runaway greenhouse effect was imminent; only 36% thought it possible and a mere 13% thought it probable.” Seventeen years later, in 2009, Gore apparently determined that he needed to revise his own revisionist history, asserting that the scientific debate over human-induced climate change had raged until as late as 1999, but now there was true consensus. Of course, 2009 is when Climategate broke, reminding us that what had smelled funny before might indeed be a little rotten.
(8) When the subject matter seems, by its nature, to resist consensus
It makes sense that chemists over time may come to unanimous conclusions about the results of some chemical reaction, since they can replicate the results over and over in their own labs. They can see the connection between the conditions and its effects. It’s easily testable. But many of the things under consideration in climate science are not like that. The evidence is scattered and hard to keep track of; it’s often indirect, imbedded in history and requiring all sorts of assumptions. You can’t rerun past climate to test it, as you can with chemistry experiments. And the headline-grabbing conclusions of climate scientists are based on complex computer models that climate scientists themselves concede do not accurately model the underlying reality, and receive their input, not from the data, but from the scientists interpreting the data. This isn’t the sort of scientific endeavor on which a wide, well-established consensus is easily rendered. In fact, if there really were a consensus on all the various claims surrounding climate science, that would be really suspicious. A fortiori, the claim of consensus is a bit suspicious as well.
(9) When “scientists say” or “science says” is a common locution
In Newsweek’s April 28, 1975, issue, science editor Peter Gwynne claimed that “scientists are almost unanimous” that global cooling was underway. Now we are told, “Scientists say global warming will lead to the extinction of plant and animal species, the flooding of coastal areas from rising seas, more extreme weather, more drought and diseases spreading more widely.” “Scientists say” is hopelessly ambiguous. Your mind should immediately wonder: “Which ones?”
Other times this vague company of scientists becomes “SCIENCE,” as when we’re told “what science says is required to avoid catastrophic climate change.” “Science says” is an inherently weasely claim. “Science,” after all, is an abstract noun. It can’t say anything. Whenever you see that locution used to imply a consensus, it should trigger your baloney detector.
(10) When it is being used to justify dramatic political or economic policies
Imagine hundreds of world leaders and nongovernmental organizations, science groups, and United Nations functionaries gathered for a meeting heralded as the most important conference since World War II, in which “the future of the world is being decided.” These officials seem to agree that institutions of “global governance” need to be established to reorder the world economy and massively restrict energy resources. Large numbers of them applaud wildly when socialist dictators denounce capitalism. Strange philosophical and metaphysical activism surrounds the gathering. And we are told by our president that all of this is based, not on fiction, but on science — that is, a scientific consensus that human activities, particularly greenhouse gas emissions, are leading to catastrophic climate change.
We don’t have to imagine that scenario, of course. It happened in Copenhagen, in December 2009. It will happen again in Paris, in December 2015.
Now, none of this disproves the hypothesis of catastrophic, human induced climate change. But it does describe an atmosphere that would be highly conducive to misrepresentation. And at the very least, when policy consequences, which claim to be based on science, are so profound, the evidence ought to be rock solid. “Extraordinary claims,” the late Carl Sagan often said, “require extraordinary evidence.” When the megaphones of consensus insist that there’s no time, that we have to move, MOVE, MOVE!, you have a right to be suspicious.
(11) When the “consensus” is maintained by an army of water-carrying journalists who defend it with uncritical and partisan zeal, and seem intent on helping certain scientists with their messaging rather than reporting on the field as objectively as possible
Do I really need to elaborate on this point?
(12) When we keep being told that there’s a scientific consensus
A scientific consensus should be based on scientific evidence. But a consensus is not itself the evidence. And with really well-established scientific theories, you never hear about consensus. No one talks about the consensus that the planets orbit the sun, that the hydrogen molecule is lighter than the oxygen molecule, that salt is sodium chloride, that light travels about 186,000 miles per second in a vacuum, that bacteria sometimes cause illness, or that blood carries oxygen to our organs. The very fact that we hear so much about a consensus on catastrophic, human-induced climate change is perhaps enough by itself to justify suspicion.
To adapt that old legal aphorism, when you’ve got decisive scientific evidence on your side, you argue the evidence. When you’ve got great arguments, you make the arguments. When you don’t have decisive evidence or great arguments, you claim consensus.
Reprinted from THE AMERICAN. This piece has been updated since its original publication.