by Lee McIntyre
There is a deeply felt sense of skepticism in scientific work. What is distinctive about scientists, however, is that unlike philosophers, they are not limited to reason; they are able to test their theories against empirical evidence.24 Scientists embrace skepticism both by withholding belief in a theory until it has been tested and also by trying to anticipate anything that might be wrong in their methodology. As we have seen, doubt alone is not enough when engaging in empirical inquiry; one must be open to new ideas as well. But doubt is a start. By doubting, one is ensuring that any new ideas are first run through our critical faculties.
What of scientists whose skepticism leads them to reject a widely supported theory—perhaps because of an alternative hypothesis that they think (or hope) might replace it—but with no empirical evidence to back up the idea that the current theory is false or that their own is true? In an important sense, they cease to be scientists. We cannot assess the truth or likelihood of a scientific theory based solely on whether it “seems” right or fits with our ideological preconceptions or intuitions. Wishing that something is true is not acceptable in science. Our theory must be put to the test.25
And this is why I believe that denialists are not entitled to call themselves skeptics in any rightful sense of the word. Philosophical skepticism is when we doubt everything—whether it comes from faith, reason, sensory evidence, or intuition—because we cannot be certain that it is true. Scientific skepticism is when we withhold belief on empirical matters because the evidence does not yet allow us to meet the customarily high standards of justification in science. By contrast, denialism is when we refuse to believe something—even in the face of what most others would take to be compelling evidence—because we do not want it to be true. Denialists may use doubt, but only selectively. Denialists know quite well what they hope to be true, and may even shop for reasons to believe it. When one is in the throes of denial, it may feel a lot like skepticism. One may wonder how others can be so gullible in believing that something like climate change is “true” before all of the data are in. But it should be a warning sign when one feels so self-righteous about a particular belief that it means more than maintaining the consistent standards of evidence that are the hallmark of science.
As Daniel Kahneman so eloquently demonstrates in his book Thinking Fast and Slow, the human mind is wired with all sorts of cognitive biases that can help us to rationalize our preferred beliefs.26 Are these unconscious biases perhaps the basis for denialism even in the face of overwhelming evidence? There is good empirical support to back this up.27 Furthermore, it cannot be overlooked that the phenomenon of “news silos” that we spoke of earlier may exacerbate the problem by giving denialists a feeling of community support for their fringe beliefs. Yet this opens the door to a kind of credulousness that is anathema to real skeptical thinking.
In fact, denialism seems to have much more in common with conspiracy theories than with skepticism. How many times have you heard a conspiracy theorist claim that we have not yet met a sufficiently high standard of evidence to believe a well-documented fact (such as that vaccines do not cause autism), then immediately exhibit complete gullibility that the most unlikely correlations are true (for instance, that the CDC paid the Institute of Medicine to suppress the data on thimerosal)? This fits completely with the denialist pattern: to have impossibly high standards of proof for the things that one does not want to believe and extremely low standards of acceptance for the things that fit one’s ideology. Why does this occur? Because unlike skeptics, denialists’ beliefs are not borne of caring about evidence in the first place; they do not have the scientific attitude. The double standard toward evidence is tolerated because it serves the denialists’ purpose. What they care about most is protecting their beliefs. This is why one sees all of the cheating on scientific standards of evidence, even when empirical matters are under discussion.
The matrix that I concocted from Sagan’s work therefore seems wrong in three important ways about denialism.28 First, it seems wrong to classify denialists as skeptics. They may use evidence selectively and pounce on the tiniest holes in someone else’s theory, but this is not because they are being rigorous; the criteria being used here are ideological, not evidential. To be selective in a biased way is not the same thing as being skeptical. In fact, considering most of the beliefs that denialists prefer to scientific ones, one must conclude that they are really quite gullible.29 Second, it also seems wrong to say that denialists are always closed to new ideas. As we will see in the example of climate change, denialists are plenty open to new ideas—and even empirical evidence—when it supports their preexisting beliefs. Finally, there may be an error in Sagan’s contrast between skepticism and openness. Sagan argues that these two notions must be balanced in scientific reasoning, which implies that they are somehow in conflict. But are they? In Massimo Pigliucci’s Nonsense on Stilts, he observes that
to be skeptical means to harbor reasonable reservations about certain claims. … It means to want more evidence before making up one’s mind. Most importantly, it means to keep an attitude of openness, to calibrate one’s beliefs to the available evidence.30
I believe that this is an accurate account of the nature of scientific skepticism. How can one be open-minded enough to suspend one’s belief, yet not be open to new ideas? Skepticism is not about closure; it is about forcing oneself to remain open to the possibility that what seems true may not be. Science is relentlessly critical, but this is because no matter how good one’s evidence, a better theory may await over the next horizon.
Denialism in Action: Climate Change
Perhaps the best example of scientific denialism in recent years is climate change. The theory that our planet is getting progressively hotter because of the release of greenhouse gases caused by human consumption of fossil fuels is massively supported by the scientific evidence.31 There remains, however, great public confusion and resistance to this, as a result of the various monied, political, and media interests that have whipped it into a partisan issue. The sordid story of how those with fossil fuel interests were able to capitalize on the foibles of human reasoning by “manufacturing doubt” where there was none—substituting public relations for scientific rigor—is a chilling tale of the vulnerability of science. The single best book on this is Naomi Oreskes and Erik Conway’s Merchants of Doubt.32 In my own Respecting Truth, I engage in an extended discussion of the epistemological fallout that resulted from public confusion not only over whether global warming is true, but also over whether the vast majority of scientists believe that it is true (which they do).33
Some of the most intellectually irresponsible rhetoric has come from politicians who have tried to impugn the reputation of climate scientists by calling climate change a hoax.34 One sometimes wonders whether they really believe this, or are just “paying the crazy tax” of trying to get elected in an environment in which a frightening percentage of the public believes it; but either way this is a shameful self-stoking cycle. The more politicians lie, the more these lies are reflected in public opinion.
One of the worst perpetrators is US Senator Ted Cruz. At an August 2015 campaign event, sponsored by the Koch Brothers, Cruz said this:
If you look at the satellite data in the last 18 years there has been zero recorded warming. Now the global warming alarmists, that’s a problem for their theories. Their computer models show massive warming that satellites says ain’t happening. We’ve discovered that NOAA, the federal government agencies are cooking the books.35
What’s wrong with this statement? Well, for one thing it isn’t true. This idea of a “global warming hiatus” has been around for years but was recently disproven by Thomas Karl, director of the NOAA’s National Centers for Environmental Information, in an article in Science in June 2015.36 To give Cruz the benefit of the doubt, perhaps he had not known of Karl’s article at the time of his speech. Yet Cruz did not apologize and retract his statement later, after Karl’s article was well publ
icized. Indeed, in December 2015, Cruz sat for a remarkable interview with NPR, which is so enlightening of the denialist mindset it is worth quoting at length:
Steve Inskeep, Host: What do you think about what is seen as a broad scientific consensus that there is man-caused climate change?
Ted Cruz: Well, I believe that public policy should follow the science and follow the data. I am the son of two mathematicians and computer programmers and scientists. In the debate over global warming, far too often politicians in Washington—and for that matter, a number of scientists receiving large government grants—disregard the science and data and instead push political ideology. You and I are both old enough to remember 30, 40 years ago, when, at the time, we were being told by liberal politicians and some scientists that the problem was global cooling.
Inskeep: There was a moment when some people said that.
Cruz: That we were facing the threat of an incoming ice age. And their solution to this problem is that we needed massive government control of the economy, the energy sector and every aspect of our lives. But then, as you noted, the data didn’t back that up. So then, many of those same liberal politicians and a number of those same scientists switched their theory to global warming.
Inskeep: This is a conspiracy, then, in your view.
Cruz: No, this is liberal politicians who want government power over the economy, the energy sector and every aspect of our lives.
Inskeep: And almost all the countries in the world have joined in to this approach?
Cruz: So let me ask you a question, Steve. Is there global warming, yes or no?
Inskeep: According to the scientists, absolutely.
Cruz: I’m asking you.
Inskeep: Sure.
Cruz: OK, you are incorrect, actually. The scientific evidence doesn’t support global warming. For the last 18 years, the satellite data—we have satellites that monitor the atmosphere. The satellites that actually measure the temperature showed no significant warming whatsoever.
Inskeep: I’ll just note that NASA analyzes that same data differently. But we can go on.
Cruz: But no, they don’t. You can go and look at the data. And by the way, this hearing—we have a number of scientists who are testifying about the data. But here’s the key point. Climate change is the perfect pseudoscientific theory for a big government politician who wants more power. Why? Because it is a theory that can never be disproven.
Inskeep: Do you question the science on other widely accepted issues—for example, evolution?. …
Cruz: Any good scientist questions all science. If you show me a scientist that stops questioning science, I’ll show you someone who isn’t a scientist. And I’ll tell you, Steve. And I’ll tell you why this has shifted. Look in the world of global warming. What is the language they use? They call anyone who questions the science—who even points to the satellite data—they call you a, quote, “denier.” Denier is not the language of science. Denier is the language of religion. It is heretic. You are a blasphemer. It’s treated as a theology. But it’s about power and money. At the end of the day, it’s not complicated. This is liberal politicians who want government power.
Inskeep: You know that your critics would say that it’s about power and money on your side. Let’s not go there for the moment. But I want to ask about this. I want to ask about facts.
Cruz: But hold on a second. Whose power—but let’s stop. I mean, if you are going to …
Inskeep: Energy industry, oil industry, Texas …
Cruz: If you’re going to toss an ad hominem.37
There are so many possible things to find fault with here that it is almost a textbook case of poor reasoning: the double standard of evidence, the subtle change of subject when he was pinned down on conspiracy theories, deliberate misunderstanding of what the “openness” of science amounts to, and the schoolyard rhetorical trick of “I know you are, but what am I?” Let us focus, however, on the one empirical claim that was repeated about the alleged eighteen-year pause in global warming. As it turns out, the government’s statistics on climate change suit Cruz just fine when they show something he likes. In this case, it was an (erroneous) IPCC assessment report from 2013 (which has since been corrected).38 This happens sometimes in science; errors are made and they need to be corrected, but not because there is a conspiracy.39 So Cruz is using an outdated, incorrect, discredited graph. But there’s another problem too. Eighteen years is a weird number. Notice that Cruz didn’t say “in the last twenty years” or even “in the last seventeen” or “in the last nineteen.” Why would he be so specific? Here one must think back to what was happening exactly eighteen years prior to 2015: El Nino.
Here we encounter the denialist’s penchant for cherry picking evidence. Despite the fact that fourteen of the last fifteen years had yielded the hottest temperatures of the century, 1998 was a (high) outlier even among those. It showed an astonishingly high pickup in global temperatures for that year only. If you think about the graph that might accompany these data, you can imagine that choosing such a high-temperature year as your base point would make 2015 look relatively cooler. When examined out of context, the eighteen-year gap between 1998 and 2015 made it look like the global temperature had been fairly flat. But it wasn’t. As we now know from Karl’s study, some of those temperature results were not only wrong but, as any scientist can tell you, you’ve also got to look at the whole graph—including the years in between—which show that 1998 was the high outlier and that there has been a steady trend in global warming over the last several decades.40 Even if one uses the old uncorrected graph, Cruz’s reasoning is flawed.
Cherry picking data is a cardinal offense against the scientific attitude, yet it is a common tactic of denialists. Few scientists would make this error. In science, one’s ideas must be subjected to rigorous tests against reality based on previously accepted standards; one can’t just pick and choose as one goes. But to an ideologue like Ted Cruz (and, as it turns out, to many who are not trained to avoid this type of error in reasoning), it may feel perfectly natural to do this. The reason is explained by cognitive psychologists and behavioral economists in their work on confirmation bias and motivated reasoning. As we’ve seen, confirmation bias is when we seek out reasons to think that we are right. Motivated reasoning is when we allow our emotions to influence the interpretation of those reasons relentlessly in favor of what we already think. And both of these are completely natural, built-in cognitive biases that are shared by all humans, even when they have been trained to guard against them. Scientists, given their education in statistics—and the fact that science is a public enterprise in which proof procedures are transparently vetted by a community of scholars who are looking for flaws in one’s reasoning—are much less prone to make these kinds of errors. Those who have been trained in logic, like philosophers and others who take skepticism seriously, can also be expected to recognize these biases and guard against their stealthy erosion of good reasoning. But most denialists? Why in the world should they care?
Of course, few denialists would agree with this assertion, primarily because they would deny that they are denialists. It sounds so much more rigorous and fair-minded to maintain their “skepticism,” which probably accounts for the recent hijacking of this word.41 In fact, some denialists (witness Cruz) go so far as to claim that they are the ones who are really being scientific in the climate change debate. The claim is a familiar one. The science is “not yet settled.” There is “so much more” that we need to know. And isn’t climate change “just a theory”? But the problem is that none of this is based on a good faith commitment to any sort of actual skepticism. It is instead based on a grave misunderstanding of how science actually works coupled with a highly motivated capitulation to cognitive bias. Yes, it is true that the science of climate change is not completely settled. But, as we have seen, that is because no science is eve
r completely settled. Given the way that science works—which we explored in chapter 2—it is always going to be the case that there are more experiments we can do or tests we can run. But it is a myth to think that one needs complete confirmation or proof before belief is warranted. (And indeed if the denialist rejects this, then why the double standard for their own beliefs?)
As for the claim that climate change is “just a theory”—so any alternative theory “could be true”—one is reluctant to give this much credence. As previously noted, gravity is just a theory. So is the germ theory of disease. As we have seen, some scientific theories are exceptionally robust. But the standard of warrant for scientific belief is not that anything goes until it has been disproven. While it is correct to say that, until it is refuted by the evidence, any theory could technically speaking be true, this does not mean that the theory is justified. Nor is it worth scientists’ time to run every fringe hypothesis to ground. Cranks should not expect to be able to kick the door in and insist that, because science is supposed to be open-ended, their theory must be tested. Science is rightly selective, and the criterion must be warrant, based on the evidence.
Scientific explanation is not made up of correct guesses or having just a few data points. Consider the Flat Earth hypothesis. If it is true, where is the evidence? Since there is none, one is scientifically justified in disbelieving it. Flat Earthers42 are customarily reluctant to say what is wrong with the evidence in favor of heliocentrism, other than that until it has been “proven,” their own theory could be true. But that is not correct reasoning. Even if someone guessed correctly at something that turned out to be true, this is not science. Science is about having a theory that backs up one’s guesses; something that has been tested against—and fits with—the evidence.