Climate Change: Should We Speak of Consensus?

In a recent lecture, Naomi Oreskes, a distinguished historian of science from the ‎University of California, San Diego, has argued that there is and has been a scientific ‎consensus that human-caused global warming is occurring. She persuasively shows that the ‎sceptical claims about human-caused global warming have not originated from within ‎the scientific community, but rather from politically motivated external ‎actors who, consciously and one would even say cynically, have been artificially ‎manufacturing controversy on the subject.‎

What are we, however, to make of this claim? On its own, the existence of a scientific ‎consensus does not indicate that the consensus view is correct. Oreskes does have a ‎point about the consensus being initially shared by people of different political views. But ‎it seems that for her – in this lecture at least – politics affect only one side of the debate. ‎Doesn’t it need to be shown that, at least once the climate debate became politicized, ‎similar political influences have not affected the other side as well?‎


True, Oreskes’ main goal seems to be to demonstrate that there is and has been a ‎consensus. Therefore, the contrarians who say that we should postpone regulation until ‎the science is more settled are wrong, and we should take action. But couldn’t the ‎contrarians just take a step back and point out all the different cases in the history of ‎science in which a scientific consensus was wrong? While not every dissenting scientist is a Galileo, there have been cases in which a scientific consensus was later overturned.  ‎

A mere consensus on a scientific theory is neither sufficient nor necessary for its being ‎true. ‎By highlighting the importance of consensus, Oreskes may play into the contrarians’ ‎hands. Moreover, she may convey a distorted image of ‎science to the public that ‎ignores the positive role of scientific pluralism ‎and dissent in justifying our theories and discovering the truth. Lastly, public ‎demand for a scientific unified front as a necessary condition ‎for warranting action may ‎lead to the undesirable consequence of silencing dissenting voices within the scientific ‎community.‎ ‎

If we are to talk about consensus at all rather than the science and the evidence ‎themselves, we should not merely ask whether there is a consensus on a scientific theory. Rather, we should ask ‎whether there is a knowledge-based consensus. A knowledge-based consensus is a consensus ‎that is likely to be justified and true.

We should ask: What properties would we generally ‎expect a knowledge-based consensus to have? In what social conditions would we expect ‎it to emerge?

Allow me to venture some suggestions as to how we might recognize a knowledge-based consensus. One condition is that the ‎agreement must be genuine. Scientists must give the same meaning to the same terms, share ‎the same fundamental background assumptions, etc. Second, when a consensus is socially diverse—shared by men and women, researchers from the private and public sectors, liberals and ‎conservatives—it’s more likely to be knowledge-based. Third, when a consensus is built on an array of evidence that’s drawn from a variety of techniques and methods, it’s less likely to be an accidental by-product of one technique — and all the more likely to be knowledge-based. ‎In my view, when these conditions are present, knowledge is the best explanation for the consensus.

As a philosopher of science, these are the factors that I would like to ‎see the public debate on climate science take into consideration. ‎

(I thank Anat Leibler, Keynyn Brysse, and Anthony Kulic for previous discussion.)


  • Thomas Hager Reply

    Where science and politics intersect, controversy almost inevitably follows. My own work — focusing mainly on the nuclear bomb debates of the late 1940s and 1950s — demonstrated that science and politics are joined at the hip, and that searching for clarity through “knowledge-based consensus” might be futile. For example, two groups of scientists looking at the same data might draw very different conclusions about its meaning. This was the case among those examining the effects of low-level radiation from fallout a half century ago. Using the same basic figures, one group (led by the AEC) concluded that risks to individuals were negligible, something akin to wearing a luminescent watch. Another group used the same data but extrapolated it to populations, concluding that fallout was causing hundreds of cases of cancer. Both were knowledge based. Both were right. The controversy continued, as I imagine it will for global warming.

  • Boaz Miller
    Boaz Miller Reply

    Thomas, thanks for your comment.
    The example you give is clearly not of a knowledge-based consensus. In fact, it is not an example of a consensus at all, as there was major disagreement over the interpretation of the same data.
    I am not saying that consensus is always present. In fact, it is relatively rare in the history of science. I am not saying that the scientific community should aim at achieving consensus. Rather, what I am saying is that in cases in which a consensus is said to be present, such as in the global warming debate, it is not enough to point out its existence as evidence for the correctness of the theory in question. Rather, it needs to be shown that the consensus has certain properties that make it likely to be knowledge-based, as opposed to other options such as a consensus that is based on masking internal disagreements, suppressing criticism, sharing a common bias, artificially presenting a unified front to fight a common foe, and so on.

  • Henry “Hank” Trim Reply

    While I agree that an examination of the political ramifications of environmentalists and environmental scientists would be intriguing and that there were obvious political motivations on both sides of the issue.
    As I understand it Oreskes’ main point is that the so called “climate debate” was purposely manufactured using fraudulent science. It is for this reason the her lecture focuses on politics of the climate deniers. They were the only agents who made fraudulent scientific clams to mislead the North American public so, it is their motivations that are important to analyze. While the scientists that were part of the scientific consensus undoubtedly had politics as well their politics did not motivate them to lie and defraud so they are less relevant to Oreskes’ study of the manufacture of a fake debate.

    • Boaz Miller
      Boaz Miller Reply

      I don’t disagree. I think that if there were less emphasis on consensus to begin with, and if it were recognized that science, like any other human activity, is political in a way that does not necessarily undermines it, affairs such as climate-gate would be perceived by the public as less devastating.

  • Science_ninja Reply

    A rather naive piece that entirely ignores the political economy of the climate debate. In Climate change billions, nay trillions, are at stake. It did not take much in terms of “seed” funding to get denalist machine going. Attention from the media provides the other set of incentives to keep denying the problem, especially if a scientific conspiracy can be alleged (as in the recent climate gate episode).

    Climate science certainly meets two of the three conditions for a knowledge based consensus (is there any other kind in science?) and the third – wide agreement among all types of groups is almost impossible these days. Heck, even things as straightforward as vaccines are suspect these days, so what of climate change with its complex data questions?

    • Mike Thicke
      Mike Thicke Reply

      Why do you describe this as naive? Are you suggesting that all critical discussions of climate science should be suppressed because they give ammunition to “the enemy”?

    • Boaz Miller
      Boaz Miller Reply

      In the political reality you describe, climate scientists are obviously pressured to present a unified front, hence the fact that they have a consensus may have less significance than what is claimed. In light of this, the post calls to change the terms in which the public debate about climate science is carried out. I would actually characterize as naive the view that there isn’t any other kind of science. The history of science proves otherwise.

  • Caroline P. Murphy Reply

    As far as I can tell, and I’m a Renaissance Art Historian by training, so don’t ask me about the science bit, but global warming has been going on since man stopped being a hunter gatherer, settled down and started tilling land and thus begins to impact the natural In other words, global warming is as old as civilization. So you could argue, without civilization there is no global warming, and without global warming there is ??? Could be interesting…

    • Curtis Forbes
      Curtis Forbes Reply

      I’m not sure any of us would like to make that argument, Caroline, but it’s definitely out there to be made. Nevertheless, I think it’s a bit early (late?) to be implicitly recommending the destruction of civilization in the interest of preventing global warming. 😉

      We can, I think, transition away from fossil fuels, capture more carbon, and develop lower-impact lifestyles while maintaining our standard of living, but it will require us to develop and build a lot of appropriate infrastructure, which unfortunately we aren’t (at least not the building part). While humanity could never have zero environmental impact on the planet, we can, no doubt, have less of a negative impact, and more of a positive impact.

    • Mike Thicke
      Mike Thicke Reply

      I didn’t know about William Ruddiman’s “Early Anthropogenic Hypothesis” until reading your post Caroline, but it seems his conclusions are controversial. I also wouldn’t jump to the conclusion that just because humans have influenced the climate since the dawn of agriculture that (a) it was an unsustainable influence or (b) it implies that civilization necessarily leads to global warming. It might be the case (and I stress my ignorance here), that human influence on the climate for most of the past 8000 years was small enough that it would never lead to serious consequences. And even if we’ve been building towards crisis for 8000 years, this doesn’t mean we can’t do better. After all, we are more technologically advanced than we ever have been.

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