Kahan on Cook et al.: 4 points

1. Scholarly knowledge. The Cook et al. study, which in my view is an elegantly designed and executed empirical assessment, doesn’t meaningfully enlarge knowledge of the state of scientific opinion on climate change. The authors find that 97% of the papers published in peer-reviewed journals between 1991 and 2011 “endorsed” the “scientific consensus” view that human activity is a source of global warming. They report further that a comparable percentage of scientists who authored such papers took that position. But as Cook et al. acknowledge, the prevalence of this position among scientists with the relevant form of expertise has been the subject of multiple past studies. Published in high-proflie journals (e.g., Science & Proceedings of the National Academy of Sciences), all report results materially identical to those in the Cook et al. paper. The methods in Cook et al. vary from the ones used in those studies but not in ways geared to addressing any question anyone might have raised about their validity. In short, no scholar familiar with these papers would have reason to adjust his or her estimate of the extent of scientific consensus on anthropogenic climate change based on the Cook et al. study.

2. Public science communication. I suspect Cook et al. would not disagree; as reflected in the introduction and conclusion of the paper, the motivation for the study was to address the U.S. public’s underestimation of the extent of scientific consensus on climate change.  Because there are already multiple existing studies on the extent of scientific consensus on climate change that reflect the same conclusion as Cook et al., it can’t be the case that the Cook et al. study would remedy the public misperception by supplying new evidence that had previously been lacking.  The only way in which Cook et al. could be expected to “change” public opinion is through the publicization of its own results via the media or via advocate messaging campaigns that rely on the Cook et al. data rather than or in addition to the existing studies.  I believe the thinking behind this science communication strategy is flawed, and in two respects.

3. The ‘knowledge deficit’ curse. First, I think it is inimical to the goal of promoting constructive public engagement with climate science to perpetuate the view that a failure to disseminate news of scientific consensus is the source of political polarization on climate change. That message—that there is a scientific consensus on climate change—has been the centerpiece of climate-science communication for over a decade. There have thousands upon thousands of stories in the media reporting this contention. The divided state of U.S. public opinion hasn’t changed.

Empirical studies aimed at trying to make sense of this phenomenon have concluded that the reason the public remains divided on the state of scientific opinion is on climate change isn’t that they haven’t been exposed to evidence on the matter but rather that when they are exposed to evidence of what experts believe they selectively credit or discredit it in patterns that reflect and reinforce their perception that scientific consensus is consistent with the position that predominates in their cultural or ideological group.

Despite this evidence—real world, and social scientific—many scientists and science communicators continue to believe that the way to dispel political polarization over climate change is simply to “get the word out” on the state of the scientific evidence, or the weight of scientific opinion; the science communication evidence I’m alluding to suggests this belief is wrong because the “word” won’t get through unless and until steps are taken to dispel the antagonistic social meanings that unconsciously motivate ordinary members of the public to fit the evidence to their group identities.  Scholars who believe this have generated a considerable body of research on identity-affirming strategies that reflect this approach (here, here & here, e.g.)—yet it is my impression (reinforced by reaction to the Cook et al. study in the media and among environmental activists) that these studies, and the evidence-based theory that supports them, remain largely outside the range of knowledge or understanding of too many (not all—consider Katharine Hayhoe and Geoffrey Haines-Stiles, and George Marshall, e.g.; but too many) scientists and communicators.

Like all claims about how the world works, the efficacy of “get the word out” as a strategy is an empirical one that not only depends on evidence but is necessarily open to persistent challenge and revision in light of additional evidence. Cook et al. might believe that the evidence in favor of a “get the word out” strategy is stronger than I do. But they neglect to call to their readers’ attention the existence of the contrary evidence, and the significance of it. If those of us who think climate change advocacy has suffered from over-reliance on the assumption that public ignorance is the source of the controversy are right, then Cook et al. can only be making things worse by failing to be sure that communicators reflect on the evidence that this is so.

4.  The polarizing effect of bludgeoning with a “science says” club. Second, I think a science communication strategy that makes “getting the word out” on scientific consensus can easily aggravate the antagonistic cultural meanings that generate polarization.  Adam Corner and his collaborators have done a study showing that presenting members of the public with news reports on “scientific consensus” on climate change can have this effect. There are additional studies on other aspects of scientific evidence on climate change, and on the use of “fact checking” and “truth patrolling,” that reinforce this conclusion.  The hypothesized mechanism that these studies investigate and furnish support for is that in a polarized environment, aggressive assertions that the “other side” is “ignoring science” or “misrepresenting the facts” is itself a potent cue that the position being attacked is important to the identity of a particular cultural group. The group’s members predictably react by digging in their heels.  That definitely doesn’t mean that science communicators shouldn’t disseminate the “facts” etc.  But it does mean that they should make sure they communicate identity-affirming cultural meanings when they they do so.

Does Cook et al. saying anything to the contrary? Of course not.

But the point is, Cook et al. doesn’t point any of this out.  All the paper says is that there’s scientific consensus on climate change, the public doesn’t perceive that, and that therefore science communicators should “get the word out.”

Those communicators who have been ignoring cultural meaning will, I worry, predictably understand this as a prescription for “more of the same.”  What they need to know is that what they’ve been doing doesn’t work, why it doesn’t, and what they should try instead.

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