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« Conditional probability is hard -- but teaching it *shouldn't* be! | Main | I ♥ Item Response Theory -- and you can too! »

"What exactly is going on in their heads?" (And in mine?) Explaining "knowing disbelief" of climate change

During my trip to Australia, I presented The Measurement Problem twice in one day, first at Monash University and then at RMIT University (slides here). I should have presented two separate lectures but I’m obsessed—disturbed even—by the results of the MP study so I couldn’t resist the opportunity to collect two sets of reactions.

In fact, I spent the several hours between the lectures discussing the challenges of measuring popular climate-science comprehension with University of Melbourne psychologist Yoshi Kashima, co-author of the very interesting study Guy, S., Kashima, Y., Walker, I. & O'Neill, S. Investigating the effects of knowledge and ideology on climate change beliefs. European Journal of Social Psychology 44, 421-429 (2014).

The challenges, we agreed, are two.

The first is just to do it. 

If you want to figure out what people know about the mechanisms of climate change, asking them whether they “believe in” human-caused global warming definitely doesn’t work.  The answer they give you to that question tells you who they are: it is an indicator of their cultural identity uninformed by and uncorrelated with any meaningful understanding of evidence or facts.

Same for pretty much any question that people recognize as asking them to “take a position” on climate change.

To find out what people actually know, you have to design questions that make it possible for them to reveal what they understand without having to declare whose side they are on in the pointless and demeaning cultural status competition that the “climate change question” has become in the US—and Australia, the UK, and many other liberal democracies.

This is a hard thing to do! 

Item response curves for OCSIBut once accomplished, the second challenge emerges: to make sense of the surprising picture that one can see after disentangling people's comprehension of climate change from their cultural identities.

As I explained in my Monash and RMIT lectures, ordinary members of the public—no matter “whose side” they are on—don’t know very much about the basic mechanisms of climate change.  That’s hardly a surprise given the polluted state of the science communication environment they inhabit.

What’s genuinely difficult to sort out, though, is how diverse citizens can actually be on different sides given how uniform their (mis)understandings are.

Regardless of whether they say they “believe in” climate change, most citizens’ responses to the “Ordinary Climate Science Intelligence” (OCSI) assessment suggest they are disposed to blame human activity for all manner of adverse climate impacts, including ones wholly at odds with the mechanisms of global warming.

This result suggests that what’s being measured when one disentangles knowledge from identity is a general affective orientation, one that in fact reflects a widespread apprehension of danger.

The only individuals whose responses don’t display this generic affective orientation are ones who score highest on a general science comprehension assessment—the “Ordinary science intelligence” scale (OSI_2.0).  These respondents can successfully distinguish the climate impacts that scientists attribute to human activity from ones they don’t.

This discriminating pattern, moreover, characterizes the responses of the most science-comprehending members of the sample regardless of their cultural or political outlooks.

Yet even those individuals still don’t uniformly agree that human activity is causing global warming.

On the contrary, these citizens—the ones, again, who display the highest degree of science comprehension generally & of the mechanisms of climate change in particular—are also the most politically polarized on whether global warming is occurring at all.

Maybe not so surprising: what people “believe” about climate change, after all, doesn’t reflect what they know; it expresses who they are.

But still, what is going on inside their heads?

This is what one curious and perceptive member of the audience asked me at RMIT.  How, he asked, can someone simultaneously display comprehension of human-caused global warming and say he or she doesn't “believe in” it?

In fact, this was exactly what Yoshi and I had been struggling with in the hours before the RMIT talk.

Because I thought the questioner and other members of the audience deserved to get the benefit of Yoshi’s expansive knowledge and reflective mind, too, I asked Yoshi to come to the front and respond, which he kindly—and articulately—did.

Now, however, I’ll try my hand. 

In fact, I don’t have an answer that I’d expect the questioner to be satisfied with. That’s because I still don’t have an answer that satisfies me.

But here is something in the nature of a report on the state of my ongoing effort to develop a set of candidate accounts suitable for further exploration and testing.

Consider these four general cases of simultaneously “knowing” and “disbelieving”:

1. “Fuck you & the horse you rode in on!” (FYATHYRIO).  Imagine someone with an “Obama was born in Kenya!” bumper sticker. He in fact doesn’t believe that assertion but is nonetheless making it to convey his antagonism toward a segment of society. Displaying the sticker is a way to participate in denigration of that group’s status. Indeed, his expectation that others (those whom he is denigrating and others who wish to denigrate them) will recognize that he knows the proposition is false is integral to the attitude he intends to convey.  There is no genuine contradiction, in this case, between any sets of beliefs in the person’s mind.

2. Compartmentalization.  In this case, there is a genuine contradiction, but it is suppressed through effortful dissonance-avoiding routines.  The paradigmatic case would be the closeted gay man (or the “passing” Jew) who belongs to a homophobic (or anti-Semitic) group.  He participates in condemnation and even persecution of gays (or Jews) in contexts in which he understands and presents himself to be a member of the persecuting group, yet in other contexts, out of the viewing of that group’s members, he inhabits the identity, and engages in the behavior, he condemns.  The individual recognizes the contradiction but avoids conscious engagement with it through habits of behavior and mind that rigidly separate his experience of the identities that harbor the contradictory assessments.  He might be successful in maintaining the separation or he might not, and for longer or or shorter periods of time, but the effort of sustaining it will take a toll on his psychic wellbeing (Roccas & Brewer 2002).

3. Partitioning. In this case, too, the contradiction is real and a consequence, effectively, of a failure of information access or retrieval.  Think of the expert who possesses specialized knowledge and reasoning proficiencies appropriate to solving a particular type of problem.  Her expertise consists in large part in recognizing or assenting to propositions that evade the comprehension of the nonexpert.  The accessing of such knowledge, however, is associated with certain recurring situational cues; in the absence of those, the cognitive processes necessary to activate the expert’s consciousness and appropriate use of her specialized knowledge will fail. The expert will effectively believe in or assent to some proposition that is contrary to the one that she can accurately be understood to “know.”  The contradiction is thus in the nature of a cognitive bias. The expert will herself, when made aware of the contradiction, regard it as an error (Lewandowsky & Kirsner 2000).

4. Dualism. The contradiction here is once again only apparent—except that it is likely not even to appear to be one to the person holding the views in question. 

Everhart & Hameed (2013) describe the Muslim medical doctor who when asked states that he “rejects Darwinian evolution”: “Man was made by Allah—he did not descend from monkeys!” Nevertheless, the Dr. can readily identify applications of evolutionary science in his own specialty (say, oncology).  He also is familiar with and genuinely excited by medical science innovations, such as stem-cell therapies, that presuppose and build on the insights of evolutionary science.

With prodding, he might see that he is both “rejecting” and “accepting” a single set of propositions about the natural history of human beings.  But the identity of the propositions in this sense does not correspond to any identity of propositions within the inventory of beliefs, assessments, and attitudes that he makes use of in his everyday life.

Within that inventory, the “theory of evolution” he “rejects” and the “theory of evolution” he "accepts" are distinct mental objects (Hameed 2014).  He accesses them as appropriate to enable him to inhabit the respective identities to which they relate (D’Andrade 1981). 

Integral to the “theory of evolution” he “rejects” is a secular cultural meaning that denigrates his religious identity. His “rejection” of that object expresses—in his own consciousness, and in the perception of others—who he is as a Muslim. 

The “theory of evolution” he “accepts” is an element of the expert understandings he uses as a professional. It is also a symbol of the special mastery of his craft, a power that entitles those who practice it to esteem.  “Accepting” that object enables him to be a doctor. 

The “accepted” and “rejected” theories of evolution are understandings he accesses “at home” and “at work,” respectively.

But the context-specificity of his engagement with these understandings is not compartmentalization: there is no antagonism between the two distinct mental objects; no experience of dissonance in holding the sets of beliefs and appraisals that correspond to them; no need effortfully to cordon these sets off from one another. They are "entirely different things!," (he explains with exasperation to the still puzzled interviewer). 

It’s actually unusual for the two mental objects to come within sight of one another. “Home” and “work” are distinct locations, not only physically but socially: negotiating them demands knowledge of, and facility with, sets of facts, appraisals, and the like suited to the activities distinctive of each.

But if the distinct mental objects that are both called "theories of evolution" are summoned to appear at once, as they might be during the interview with the researcher, there is no drama or crisis of any sort. “What in the world is the problem,” the Dr. wonders, as the seemlingly obtuse interviewer continues to press him for an explanation.

So what should we make of the highly science comprehending individual who gets a perfect score on the OCSI but who, consistent with his cultural identity, states, “There is no credible evidence that human activity is causing climate change”?

I feel fairly confident that what’s “going on” in his or her head is neither FYATHYRIO nor “compartmentalization.”

I doubt, too, that this is an instance of “partitioning.”

“Dualism” seems like a better fit to me.  I think something like this occurs in Florida and other states, where citizens who are polarized on “climate change” make use of climate science in local decisionmaking.

But I do not feel particularly confident about this account—in part because even after constructing it, I still myself am left wondering, “But what exactly is going on in their heads?”

It’s not unusual—indeed, it is motivating and exhilarating—to discover that one’s understanding of some phenomenon that one is studying involves some imperfection or puzzle.

Nevertheless, in this case, I am also a bit unsettled. The thing to be explained took me by surprise, and I don’t feel that I actually have figured out the significance of it for other things that I do feel I know.

But after my talk at RMIT, I put all of this behind me, and proceeded to my next stop, where I delivered a lecture on “cultural cognition” and “the tragedy of the science communications commons.” 

You see, I am able to compartmentalize . . . .


D'Andrade, R.G. The cultural part of cognition. Cognitive science 5, 179-195 (1981).

Everhart, D. & Hameed, S. Muslims and evolution: a study of Pakistani physicians in the United States. Evo. Edu. Outreach 6, 1-8 (2013).

Hameed, S. Making sense of Islamic creationism in Europe. Unpublished manuscript (2014).

Kahan, D. M. Climate Science Communication and the Measurement Problem, Advances in Pol. Psych. (in press).

Lewandowsky, S., & Kirsner, Kim. Knowledge partitioning: Context-dependent use of expertise. Memory & Cognition 28, 295-305 (2000).

Roccas, S. & Brewer, M.B. Social identity complexity. Pers Soc Psychol Rev 6, 88-106 (2002).

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Reader Comments (124)

I don't think there is such a contradiction/puzzle here as you are suggesting.

August 19, 2014 | Unregistered CommenterPaul Matthews

@Paul Mathews:

But apparently you don't have room in the margin to set forth your solution. No worries-- I'm sure it will occur to the rest of us, too!

August 19, 2014 | Registered CommenterDan Kahan

The conundrum seems so illogical and unexplainable so maybe it is time to revisit your base assumptions. The large gap between the "beliefs" of the high science literacy groups means that one side or the other is wrong.
Perhaps you should be psycho analyzing the motivations of both sides of the discussion. The gap can easily be explained by the psychology of mass delusion. The biggest Cultural Cognition story in history may be how so many really intelligent people came to fervently "believe" in a series of theories that are poorly supported by computer models and very little empirical evidence.

August 19, 2014 | Unregistered CommenterBill

Have you asked whether CO2 absorbs infrared? That usually cuts to the heart in arguments, so it might help explain what people are actually thinking.

August 19, 2014 | Unregistered CommenterJames Salsman

"So what should we make of the highly science comprehending individual who gets a perfect score on the OCSI but who, consistent with his cultural identity, states, “There is no credible evidence that human activity is causing climate change”?"

Umm, have you seriously considered the notion that the climate change (TM) sceptic's rejection of the evidence for significant anthropogenic climate change is far more directly related to their scientific knowledge and general intellectual approach rather than their 'cultural identity'? That's what Paul is getting at I believe and it seems a perfectly obvious conclusion to draw. Also, I think you will find that most sceptics refute the evidence for 'significant and dangerous' anthropogenic global warming rather than dismiss out of hand ANY influence at all that humans may have on the climate. That is, after all, the basis of most political and other debate. There would be much less debate and much less concern if humans played only a very minor part in climate change, most of which was proved to be due to natural causes.

August 19, 2014 | Unregistered CommenterJaime Jessop


Yes, I've considered that. And considered it & considered it. And very seriously too. The study from which the data I'm summarizing comes builds on extensive evidence relating to that very question.

The position people take on whether human activity is generating global warming & the on the dangers that we face as a result does indeed have a correlation to general science coprehension & intellectual approach.

But the sign of it depends on their cultural outlooks: if they are culturally predisposed to become more concerned, then greater science comprehension & critical reasoning make them more concerned; if they are inclined to be skeptical, then greater science comprehension & critical reasoning make them more skeptical

The best explanation for why people -- on both sides of the debate-- continue to to think that their group's superior reasoning capacity explains why the other side sees things differently is their vulnerability to the very sorts of cultural-cognition dynamics that explain polarization on climate change in the first place.

@PaulMathews is very familiar with this literature. I'd be delighted to hear *from him* what he thinks.

August 19, 2014 | Registered CommenterDan Kahan

Lets start with a concise statement of what you and the audience member who asked the question think is a puzzle - people can be quite knowledgeable about climate science but not accept that the earth is getting warmer mostly because of fossil fuels.

Look at the wording of the OCSI questions. They all start with "climate scientists believe that...".
(And they are cleverly designed so that about half of them are in fact true and half are false, so ticking the most alarming answers would lead to a score near zero on the scale).

Now you've found, see the "Don't go there" post from a couple of days back,or other previous posts, that people who are sceptical about climate change do just as well (Lee Jussim claims even better) on this
test as believers.

So there's a significant number of people (by the way, it would be nice to see the full data, so we can see exactly how many) who score highly on the test but are sceptical. In other words, they are aware of what most climate scientists say, but they don't accept it.

So there's no contradiction here. But reading the post carefully again I don't think you said there was :)
It is, though, a very interesting result and worth discussing further...

August 19, 2014 | Unregistered CommenterPaul Matthews

Dan, I think the problem here is that you are reluctant to allow for the fact that people may have a free-wheeling intellect which functions largely independently of their cultural/psychological predispositions. You assume a priori that scientific questioning is geared to 'vulnerabilities' to cultural mindset traps, ready and waiting to spring shut in the mind of the enquirer. I'm a little more generous in my approach in that I believe intellectual curiosity and questioning can - and does, often - function ostensibly free of interference from these psychological/cultural vulnerabilities which you identify. On the one hand, the tendency for scientifically or otherwise highly educated people to believe in CAGW is not so much a predisposition to be concerned, but a primary failure to think critically, for whatever reason, consciously or unconsciously, psychological or cultural. On the other hand, sceptics, many educated in science, engineering and mathematical disciplines, do quite naturally employ logic and critical reasoning in their thought processes and they constantly find that many of the claims of mainstream climate science are at odds with their way of thinking. That's not a psychological/cultural vulnerability; it is the result of a group of people positively engaging in questioning what has become accepted wisdom.

Sorry that's not what you want to hear (though it is but an opinion), it probably sounds conceited in some respects and I am sure you will disagree because it rather elevates sceptics above CAGW advocates but, in life, all things and all people are not equal and some are more right than others, or at the least, more right in their approach to solving problems.

August 19, 2014 | Unregistered CommenterJaime Jessop

Dan, first off, I think your research on the relationship between U.S. political beliefs, OCSI & views on AGW are very interesting, and you're generally doing a good job on this! So, keep it up!

However, as others have mentioned, your "puzzle" is not as puzzling as you imply.

You say,

...these citizens—the ones, again, who display the highest degree of science comprehension generally & of the mechanisms of climate change in particular—are also the most politically polarized on whether global warming is occurring at all.
[bold added for emphasis]

Then you post a figure showing two groups who (as far as we know) agree there has been "global warming", yet disagree over whether the cause of this is "(a) mostly because of human activity such as burning fossil fuels or (b) mostly because of natural patterns in the earth’s environment"

As I mentioned on Twitter, on our blog, we have grouped the views of several prominent climate researchers along a scale ranging from those who are convinced global warming is a man-made crisis (“1″) to those who believe that global warming can be entirely explained by natural variability (“5″) - see Have you read this yet?

I would guess that most (if not all) of the researchers on that scale would score very highly on your OCSI. What about you? They seem to have reached their conclusions on the basis of their high OCSI and NOT in spite of their high OCSI as you seem to be implying.

Certainly, you do seem to have found a strong relationship between how people in the U.S. with high OCSI answer that question, and whether they are Republican/Democrat. And that’s an interesting result, although here in Ireland we don’t have such a pronounced partisan political divide.

To me, your work suggests that, in the U.S., your political beliefs play a significant role in your views on AGW – perhaps more than your actual scientific knowledge. That’s an interesting result.
However, you seem to be implying that the “puzzle” is why high OCSI “Conservative Republicans” tend to think GW is a mostly natural phenomenon. But, why isn’t the corollary also a “puzzle” for you?

I appreciate that you might personally believe that the “Liberal Democrat” high OCSI group are “right” and that there’s something odd with the other group for getting (what you perceive to be) “the wrong answer”. But, if their political beliefs are influencing their “mostly because of natural patterns” choice, then similarly the Liberal Democrats’ political beliefs are also influencing their “mostly because of human activity” choice. Whenever they are choosing their answer on this scientific question based on their political beliefs, then neither group is “right”, regardless of their answer.

As Winston Churchill once noted,

Man will occasionally stumble over the truth, but most of the time he just picks himself up and stumbles on.

If you are going to say that the high OCSI Conservative Republicans who disagree with you on AGW are “wrong”, won’t you have to also say that the high OCSI Liberal Democrats who agree with you are similarly “wrong”?

August 19, 2014 | Unregistered CommenterRonan Connolly

For the sceptics here, the question to ask is why the more scientifically literate a left-winger is, the more likely they are to 'believe in global warming'? What's going on in their heads?

It's not that they're ignorant and it's not that they're stupid. It's not that they can't do maths or that they're ignorant of scientific principles. There are lots of obviously perfectly intelligent people who - no matter how much you go through the mathematically incontrovertible evidence with them - simply will not believe that there could be anything wrong with the climate science consensus. Why? What's going on?

And what evidence do you have to support your hypothesis? Does it fit Dan's data?

August 19, 2014 | Unregistered CommenterNiV

Your premise seems to be that 'well thinking scientifically aware individuals will agree to human activities as the major cause for global warming.'
If I understand correctly you have sought to find an explanation to the outcome of your research which suggests in the real world quite a few well thinking scientifically aware people do not see human activities as a probable major cause for global warming.
You have come up with quite a few explanations and didn't find a fitting one yet.
May I suggest that your premise in the first place may have been flawed?

August 19, 2014 | Unregistered CommenterJelte Arntzen

So here are some things that might be going on in their heads (to explain why they know what most climate scientists say, but dont agree with it).

1. They might be familiar with many previous instances in the history of science where the expert consensus has turned out to be wrong. See my latest blog post. They might know some Feynman quotes about the ignorance of experts and not making the mistake of trusting experts again.

2. They might think that scientists have a tendency to exaggerate the importance of their own research. They might even think that the grant funding system, with its strong competition and emphasis on impact, forces scientists to do this if they want to succeed.

3. They might have political views that make them unsupportive of big-government, interventionist, anti-growth policies.

4. They might think that academic scientists tend to have left-wing views that lead to biased research. Or even that people with established activist views are attracted into the field,creating bias.

August 19, 2014 | Unregistered CommenterPaul Matthews


Agreed. But then for 1, 2, and 4 the question is why on most scientific subjects they trust scientists without argument. It's only a small handful that are politically contested. Why don't people do the same on black hole physics or the Higgs boson?

But as I said, from a climate sceptic point of view, the mystery is why scientifically literate people on the left refuse to accept the evidence of the flaws in climate science. They'll make excuses for, or dismiss as unimportant events that would leave them howling if someone had used such methods to support something like homeopathy. They'll read 'harry read me' and tell me that's how science is done. They'll say the errors in MBH 'don't matter', nor does the fact it passed multiple layers of review without anyone ever checking it, or spotting the catalogue of problems.

Why? What's going on in their heads? They know how science works, they apply the principles correctly when discussing homeopathy or intelligent design or anti-gravity perpetual motion devices. Our host Dan is clearly capable of picking apart deep technical problems with papers in social psychology, survey bias and obscure issues with Bayesian deduction, but totally fails to do so when reading the 97% surveys or the far more transparent flaws in Lewandowsky. Why are their critical faculties suddenly disabled when it comes to climate change?

Do you see that there is indeed a mystery here? Never mind the fact that Dan is on the believer side and interprets the results his way - the phenomenon and the mystery is symmetrical. The question can be turned round, and applied to the believers. Nor does Dan seem to mind if we do so - we're all working on the same problem, after all.

August 20, 2014 | Unregistered CommenterNiV

Dan, what do the two political poles say on the question as to whether your blog is infested with a blatant astroturf squad, producing comments tailor-made to your particular position of influence over their colleagues' credibility?

August 20, 2014 | Unregistered CommenterJames Salsman

I was thinking on your results last night and I think what they are indicating is that the answer to the question

”[Is the earth] getting warmer (a) mostly because of human activity such as burning fossil fuels or (b) mostly because of natural patterns in the earth’s environment?”
is mostly a political one (at least in the U.S.), and not one based on actual scientific evidence.

1. If the scientific evidence clearly pointed to one answer, i.e., (a) or (b), then we should expect the number of people picking that answer to increase as their OCSI increased, shouldn’t we? However, instead we get a strong divergence (based on political views).

2. If the answer to the question was not mostly political, then there shouldn’t be a divergence based on political views.

What do you think yourself?


Taking this further, let us assume that being a Liberal Democrat makes you more inclined to answer (a) and being a Conservative Republican makes you more inclined to answer (b). Does that seem reasonable?

Then presumably the high OCSI Liberal Democrats who answered (b) [looks like 15% ± 5%?] and the high OCSI Conservative Republicans who answered (a) [looks like 10% ± 5%?] came to their conclusion for “non-political” reasons.

Of course, there should be a similar percentage of high OCSI people who also got the answer expected by their political beliefs... but for non-political reasons.

So, if we double those 10-15% values, we should get a very crude estimate of the percentage of high OCSI people who answered the question for "non-political" reasons. From “eyeballing” your graph, I’m estimating 20-30%... Maybe you could get a more accurate estimate from the raw data?

Anyway, that suggests to me that amongst high OCSI people, the answer to that key question (“a or b?”) is 70-80% political. Your findings seem to be suggesting that their answers are not based on scientific evidence. What does everyone else think?


I would hope (!) that most practising climate scientists would score a fairly high OCSI in your test. So, it seems likely that this political divergence is at least as pronounced in the climate science community (in the U.S., at least).

In light of this, I wonder what percentage of practising climate scientists in the U.S. are Liberal Democrats and what percentage are Conservative Republicans...

Does anyone know this? I found this paper from 2005 (Rothman et al., 2005 - summary here) which looked at the wider question of U.S. academics. They found that 72% of U.S. professors are liberal vs. 15% conservative, and 50% Democrats vs. 11% Republicans.
Do you think Rothman et al., 2005 is a reliable estimate, and is it still relevant?

If so, do you think similar ratios would apply to U.S. climate scientists in academia?

August 20, 2014 | Unregistered CommenterRonan Connolly

@James Salsman:

I do feel often that I'm trapped in one of my own studies & can't get out.

But in fact, I think most of the commentators recognize that the dynamics I'm trying to make sense of don't discriminate on cultural orientation & that they themselves no doubt are vulnerable to it. That's how I feel.

I also am eager to have any such influence in me counteracted -- and suspect they are too.

Self-examination doesn't help: it's not the case that *knowing* such things means one can distinguish in oneself the views that are being shaped by these mechanisms from the ones that aren't.

Nor is anyone else in a position to be able to see motivated reasoning operating in another person at the individual level (even if the evidence strongly suggests its work in aggregations of opinions) -- and so one is justified in ignoring someone who accuses him or her of being "biased."

Put all this together & I think all any of us can do is offer our best arguments & entertain responses.

I know you were just being playful but you there's a serious point here too.

August 20, 2014 | Registered CommenterDan Kahan

@Paul Mathews:

I agree that the mystery is solved if we posit that "conservative republicans" (using that label just to characterize whatever the unobservable characteristic is that connects those who are high in science comprehension & "reject" climate change) understand what "climate scientists* are saying but "don't believe them," while "liberal democrats" who are high in science comprehension both understand *&* believe.

As I explain in the paper, I have other reasons for thinking that isn't the answer. The short answer is that the tendency on *both sides* to attribute the "other side's" resistance to one's arguments to *their* "distrust of science" reflects the same kind of identity-protective reasoning as the tendency to attribute the other side's resistance to some defect in their reasoning capacities. Every time one tries to test the claim directly -- by experimental means-- it dissolves & leaves behind the residue of symmetrical motivated reasoning on both sides..

But I don't doubt that this is what is "going on in the heads" of particular people. If you tell me that is how *you* see things -- & how various people you talk to do -- I accept that.

But I don't think it plausibly explains the patterns of public opinion I am examining. Just as it would be a mistake for me to treat explanations for aggregations of opinions as explaining why individuals believe what they do, it is a mistake for individuals to treat why they believe things as an explanation for aggregations of opinion.

Notice how those on both sides make broad sweeping claims about the connection between positions & differences in the sides' critical reasoning capacity generally & comprehension of the evidence on climate change in particular.

They are both comically mistaken: the truth is the overwhelming majority of ordinary members of the public on *both* sides have very modest powers of critical reasoning & are filled with misunderstanding about the mechanisms of climate science & what "climate scientists believe" about the same.

Is it informative, under these circumstances, to invoke "trust" or "distrust" of scienitsts as an explanation for variance in public opinion? The people whose opinons we are chacaterizing at that point are ones who can't accurately identify what scientists believe. So even if we thought they had differing levels of "trust" in climate scientists (and again, the evidence doesn't support that claim), it would have to be the case that something other than engagement with the content of the scienitsts' views was explaining variance in how much opposing groups of citizens "trust" them.

But now we are talking about a smaller subset of those on both sides who seem to display higher levels not only of science comprehension but of awareness of the mechanisms of climate science as understood *by* climate scientists. For *them*, is variance in "trust" the explanation?

Maybe, but it seems ad hoc to me....

Maybe we could come up w/ a test?

What if we re-ran the experiment that we did in Cultural Cognition of Scientific Consensus & included measures of science comprehension or OCSI. I predict that we'd find the tendency to condition recognition of a scientist's expertise on his having the position that fits one's cultural predispositions would intensify as subjects' OSI & OCSI scores increased. If that is how people are reasoning, then those who are high in OSI & OCSI will be the *least* likely to change their mind in the face of valid contrary scientific opinion -- b/c they'd be the least willing to recognize the views of such scientists were valid. I take it you would predict the opposite result? That those highest in OSI & OCSI would converge?

BTW, forget climate change for a second (I try to forget about it for at least 23 hrs a day; I'm pretty sure that improves my ability to think about it for the remaining hr). What do you make of the situation in case 4-- the Pakistani Dr described by Hameed? I think this is a real phenomenon & is very interesting. The Dr thinks that those who can't understand his stance(s) are obtuse; I think he has a point.

August 20, 2014 | Registered CommenterDan Kahan


1. No, I'm not convinced that one can infer the state of the scientific evidence from whether people high in science comprehension converge.

Yes, I can see, certainly, why one might expect those highest in science comprehension to be least subject to cultural conformity effects & thus to converge on the best evidence generally.

But experiments -- in which the strength of the evidence is held constant & the cultural significance of it manipulated -- suggest that those highest in science comprehension are (at least on issues that have this weird polarizing quality) the most disposed to conform their view of the strength of the evidence to their cultural predispostiions.. If these experiments are validly modeling how people process information in the world, then we woudl have reason to expect *nonconvergence* despite common access to valid evidence. (I feel impelled again to state that I think this is not the norm; it is a pathology-- but we are trying to understand exactly that, so we can treat this impediment to englightened collective decisionmaking).

2. It's interesting to try to see if we can learn things from "nonconformers," including those who are higher in science comprehension. But so far I've not myself been able to learn much....

3. I don't myself believe that the data I'm rpresenting can tell us anything about how professional scienitstis reason. Indeed, I think cultural cognition is part of the machinery by which nonexperts are able -- usually reliably -- to discern who is an expert and what it is that experts have been able to figure out w/ use of the specialized knowledge & methods they employ. Expert judgment is another thing entirey. I am sure it is subject, too, to biases of various sorts & possibly even to ones that account for the polarizing distortions of reason we see in public opinion. But the claim that this is going on would need evidence based on samples of expert scientists; one simply can't draw inferences from them from the public b/c whether expert judgment is distince is the very issue under consdieration.

4. I also don't think OSI is valuable for assessing what scientists know. I discussed this recently (also take a look at , which originally was gonig to be a post on why Sir Fred Hoyle would be indistinuishable from a smart highschool student on OSI, but then went off on its own path).

Of coruse, I could be wrong on every one of these points. This is how I see things based on the weight of the now-available evidence

August 20, 2014 | Registered CommenterDan Kahan


What you say *is* what I want to hear. It just isn't what I see in the evidence.

I've tried very manner of reasoning style dispositoin measure I can -- from science literacy to numeracy, form critical refelection to actively open-minded thinking. They all show the same thing: magnification of the disposition to fit evidence to cultural predispositions (at least on the weird class of issues under discussion; I do think it is a mistake to examine these dynamics only w/r/t those issues that display the characteristics in question as opposed to all the ones that could).

I also find that people who are highest in those capacities are the most likely to use their capacities to construe evidence to fit their predispositon to believe "the other side" is less open-minded than they are.

Am happy to reconsider all this. But at least take a close look at the work to date & tell me where you think the holes are & what you'd propose to do to fill them.

August 20, 2014 | Registered CommenterDan Kahan


My first hypothesis would be @RonanConnolly's-- that high science-comprehending woudl converge on best evidence.

But as I explained, the evidence doesn't seem to fit that hypothesis.

I don't assume that everyone would converge on any particular position on climate change, either, if the @RonanConnolly hypothesis were true. They might well converge on conclusion that evidence supports not firm conclusions-- when the eivdnece is indecsive, it is biased to default to the view that it supports one's political predispositions!

August 20, 2014 | Registered CommenterDan Kahan


You are right, of course: the question is same -- mystery just as deep-- no matter what one thinks about global warming.

Put aside whether the "knowing disbelief" issue is posed by the data on OCSI .... What do you make of Everhard & Hameed's Pakinstani Dr? He thinks we (for being the confused people the clever interviewer is speaking for) are obtuse. I have this feeling that he -- someone in a society that has a long way to go to make the transition to being a secular liberal democratic market state -- gets something that we, as the lucky inhabitants of such states, don't.

BTW, as I adverted to in one of my last comments, the "I ♥ IRT" post started out as a response to your incredulity at my statement that a smart high school student & Sir Freddie "Mercury" Hoyle would score the same on OSI. Maybe you can see why?

August 20, 2014 | Registered CommenterDan Kahan

Fascinating post and discussion. With regards to the question

”[Is the earth] getting warmer (a) mostly because of human activity such as burning fossil fuels or (b) mostly because of natural patterns in the earth’s environment?”

I don't know how to answer this question. Given the inadequate evidence (lack of knowledge about solar impacts, inability to adequately model the network of multidecadal internal variability, etc) my current best assessment is 50-50. And this is something I have studied carefully for the past 5 years and have published papers on.

Politically I am independent, with libertarian leanings. I have no idea what we should do about climate/energy policy - it is indeed a wicked problem. I don't associate with any 'group' on this - I've been thoroughly insulted by both 'sides'. I am do my best to think this through for myself, and it isn't easy, see my paper Reasoning about climate uncertainty

I cannot understand why more people don't view all this as I do - we just don't know how much humans have contributed to climate change. The manufactured consensus by IPCC assessment process has resulted in massive confirmation bias and groupthink. Perhaps the unexplainable skeptics are thinking like I am.

August 20, 2014 | Unregistered CommenterJudith Curry

As usual, Judith Curry is on the mark. We just don't know, and much money has been spent by the IPCC and others without bringing us any closer to knowing.

Further, much more has been spent on trinkets like windmills which don't solve a problem which we are not even sure we have.

Let's do the science looking at all the variables and maybe then we will know if there is a problem and how big it is.

If there is, then let's have some solutions which actually work, and are cost effective.

Until then, both sides have a faith, not science based position so of course they disagree.

August 20, 2014 | Unregistered CommenterSoarer

Dan -

You're reading too much into this. It's clear what's going on.

"Scientific literacy" is associated with "skepticism" among "conservatives" (using that imperfect term for now) because they are unbiased; an unbiased view of the science means that one can see that there is no evidence of any real risk of ACO2 negatively affecting the climate.

"Scientific literacy" is associated with belief that ACO2 does pose a risk among "liberals" (using that imperfect term for now) because they are biased; the only reason that they think that there's evidence of a risk of significant impact on the climate from ACO2 is because they allow their political orientation to affect their reasoning.

See how simple that is?

Among "conservatives" greater understanding of science means increased clarity in reasoning - hence the association between greater polarization and greater scientific literacy for that group.

Among "liberals" greater understanding of science means decreased clarity in reasoning - hence the association between greater polarization and greater scientific literacy for that group.

The basic mechanism of "motivated reasoning" - you know, how identification mixes with fundamental components of cognition and psychology to influence how people reason - only works with "liberals." "Conservatives" are immune to such influences.

And all that identity-aggressive and identity-defensive behaviors that are so abundantly found among "skeptics." That's just coincidence. Don't think, in any way, that those behaviors can support a conjecture that motivated reasoning is at play among "conservatives.

Identity-aggressive and identity-defensive behaviors only indicate motivated reasoning among liberals.

Once you see that human psychology and cognition are completely different among "conservatives" than among "liberals," everything comes into focus - and you can see how simply all of this can be explained.

Glad I cleared that up for ya!!!

August 20, 2014 | Unregistered CommenterJoshua

Of course, there are some other theories for the differences in association between scientific literacy and views on climate change among "conservatives" and "liberals," respectively.

If you look at where "scientifically-literate" "skeptics" gather in the Internet, you can see some of those theories in display. Now before you look at these links - remember that among "conservative" "skeptics," scientific-literacy is associated with a more evidence-based view of scientific evidence. Ok, ready to look at the links now?

One theory is that scientifically-literate "liberals" are trolls:

Another theory is that scientifically-literate "liberals" are paid to voice their views, independent of weighting evidence scientifically:

August 20, 2014 | Unregistered CommenterJoshua

Judith Curry: "I cannot understand why more people don't view all this as I do"

A lot of the issues on this thread are hard, and I'll happily admit to being as confused as Dan on the principle points. But there is an answer to Judith's problem. Most scientists don't agree on the " 50/50 + there's too much uncertainty" position because no sufficiently convincing evidence to support it has been presented. This position is simply a Bayesian prior without any actual positive evidence to confirm it - no study that anyone has published that I am aware of has ever given that as the most likely situation. On the other hand, the attribution statements in AR4 and AR5 are based on multiple studies, allow for uncertainties in solar forcing, and have estimated uncertainties that rule out <50% contribution at least at the 10% level. This is not 'groupthink' on 'confirmation bias' on the part of mainstream climate science, but rather the opposite.

Some links:
On attribution
The AR4 attribution statement
The IPCC AR5 attribution statement

August 20, 2014 | Unregistered CommenterGavin

Gavin says: Most scientists don't agree on the " 50/50 + there's too much uncertainty" position because no sufficiently convincing evidence to support it has been presented.

The problem is with how the problem has been framed, see my paper Reasoning about climate uncertainty. Failure to adequately explore uncertainties in external forcing and how this influences attribution (Ben Santer was very concerned by this at the APS Workshop), lack of understanding of solar indirect effects and failure to understand the network of modes of internal multidecadal variability leaves a simple solution - external forcing dominated by anthropogenic factors.

Absence of evidence is not evidence of absence. Your argument fails to acknowledge ambiguity and ignorance regarding climate dynamics, assuming that everything of significance happening on a timescale greater than a decade is is associated with external radiative forcing.

Your flashlight has a narrow beam.

August 20, 2014 | Unregistered CommenterJudith Curry

Judith sums it up rather nicely and draws us rightly back to the science, which musings upon 'what goes on inside the minds of sceptics' tend to detract from. The impartial and unadulterated scientific evidence gathered thus far, from my point of view, as a layperson on the outside looking in, unlike Judith who is in the 'thick of it', points to AGW being real, but not especially significant or 'dangerous' when compared with the magnitude of natural forcings. Climate science is still a relatively new field and knowledge of the way climate and weather patterns interact with various natural forcings is still very much in the development stage and far, far from 'settled'. Even the supposed 'settled' science of CO2 radiative forcing is not, as some like to claim, a done deal, simply a matter of basic physics.
So one wonders why the need for studies like this which seeks to investigate why intelligent, scientifically literate people question a climate change scenario which is based more upon risk assessment and political expediency than it is upon hard scientific evidence? It appears that people are looking for excuses why other people question the reality of dangerous man-made global warming rather than looking at the more obvious and probable reasons.
Any study like this must surely take as its starting point the assumed 'fact' that CAGW is real and the scientific evidence for it is compelling. It must, otherwise there would be no point to it. Hence in the graph above, we see that 'ordinary climate science intelligence' is plotted against 'probability of correct answer' which automatically assumes that option (a) is right whilst (b) is wrong. Alas, that just is not the case. That's not what I - or any other 'psychologically/culturally compromised' sceptic - says; it is what the unadulterated scientific and observational evidence says. The jury is still out.

August 20, 2014 | Unregistered CommenterJaime Jessop

==> " The impartial and unadulterated scientific evidence gathered thus far, from my point of view, as a layperson on the outside looking in, unlike Judith who is in the 'thick of it', points to AGW being real, but not especially significant or 'dangerous' when compared with the magnitude of natural forcings. "

The question is, do you think that the evidence gathered thus far shows that ACO2 poses a risk of being especially significant or 'dangerous' when compared with the magnitude of natural forcings?

Surely, you are aware that the consensus view of the impact of ACO2 is exactly that, that CO2 emissions pose a risk of especially significant or 'dangerous' impact on our climate?

==> "So one wonders why the need for studies like this which seeks to investigate why intelligent, scientifically literate people question a climate change scenario which is based more upon risk assessment and political expediency than it is upon hard scientific evidence?

Here's something that I think is interesting. Why would intelligent, scientifically literate people describe the consensus view about climate change as indicating anything other than a risk of serious impact from ACO2? Why would they look right past the "hard scientific evidence" that your characterization is inaccurate?

Here's an example:

Now it seems to me that scientifically-minded people could very well-argue the reasoning and science of Emanuel's evaluation of the magnitude of various probabilities, but what would cause them to mischaracterize his position as anything other than what he says?:

"...the importance of societal risk in the low-probability tail of the climate change probability distribution. "

August 20, 2014 | Unregistered CommenterJoshua

Judith, You appear to be simply making declarations based on how you feel about the situation rather than demonstrating that there is a problem. Effectively you are asking people to approach the topic with exactly the same preconceptions as you but without any evidence to convince anyone that they are more valid than theirs. This isn't how issues get resolved in science. If you think an approach is flawed, show that it gives the wrong answer in idealised cases, or that it is incoherent with something for which there is far more evidence, or something. I am however curious about your 50/50 mean estimate. What is that based on? It is a quantitative statement so presumably must be based on a quantitative calculation...?

In any case, to dismiss the work that has been done (which, if you read it, does account for errors in forcings and responses and for different estimates of the magnitude and structure of internal variability), is totally your right. But don't be confused about why other scientists don't agree with you.

August 20, 2014 | Unregistered CommenterGavin

Going back to Joshua's comment:

It reminded me of a interview by Melanie Philips, when she talked to playwright Richard Bean about the how the intelligent Guardian reading Left, reject scepticism in climate science, how this peer pressure infects the media and increasingly politics in the UK.

August 20, 2014 | Unregistered CommenterAndrew


I wouldn't claim that the "mystery is solved". I'm just saying there is no contradiction and there are various possible explanations for the observations, some of which I listed. And Judith gives another one, groupthink, which is strengthened by the 'circling the wagons' response to criticism.

The way to find out "what's going on in their heads" is of course to ask them!
So maybe next time you or anyone else does one of these surveys asking about knowledge, opinion and political views, there could be a box at the end asking "please explain in 100 words why you believe warming is human/naturally caused".

What do I think about case 4? Well that gets into religion which is something I have no understanding of! And I don't think there's a meaningful analogy there - at the risk of getting myself in deep trouble, religious people and especially muslims have deeply held beliefs that heavily influence their lives and thinking.

Somewhat related to that, one final thought on the politics thing. In US elections, only just over half the population turn up to vote, and it's not much higher here in the UK. If half the population can't be bothered to vote, does it make sense to say that their views on climate change are determined by their political views?
See Judith's comment about being independent and not part of a group.

August 20, 2014 | Unregistered CommenterPaul Matthews

Gavin, I've written 100,000's of words on my blog and published several papers on this topic, not just my 'feelings'. What kind of defensible reasoning framework allows a highly confident attribution of warming since 1970, but has no explanation for comparable warming from 1910-1940. Etc.

The real cultural cognition issue is why so many climate scientists are convinced with high confidence based on such flimsy and ambiguous evidence.

August 20, 2014 | Unregistered CommenterJudith Curry

You have it backwards. The question is why, with increasing knowledge politically left leaning people become more certain of something that is clearly unknown.

August 20, 2014 | Unregistered Commenteraaron

"The question is, do you think that the evidence gathered thus far shows that ACO2 poses a risk of being especially significant or 'dangerous' when compared with the magnitude of natural forcings?"

Joshua, I don't think in terms of this rather nebulous concept of 'risk' which you so cleverly use to rephrase my original statement. As I stated, the evidence gathered thus far, from my point of view, points to AGW not being especially significant or dangerous, i.e. climate sensitivity being at the low end of IPCC estimates.

"Surely, you are aware that the consensus view of the impact of ACO2 is exactly that, that CO2 emissions pose a risk of especially significant or 'dangerous' impact on our climate?"

Whose consensus view? And what justified, quantifiable 'risk' are we talking about? Risk (probability) varies from 0 to 100%. I'm afraid I have very little regard for consensuses in science, whether real or 'cook'ed up. I think you will probably find that there is no overwhelming consensus viewpoint among ALL geo-scientists when it comes to the question as to whether man-made global warming is significant and dangerous, or not. But that's beside the point. 99.9% of all scientists everywhere might agree that CAGW is real and happening but it is worth absolutely nothing if the actual scientific evidence does not confirm that viewpoint - and the actual scientific evidence, from where I'm standing, is revealing that natural climate forcings are, at the very least, significant compared to anthropogenic (enough to cause the 'pause' for instance) and may possibly overwhelm any anthropogenic signature.

August 20, 2014 | Unregistered CommenterJaime Jessop

Or, to reframe the question again, "When observing new a phenomena, why do knowledgeable liberals tend to attribute the phenomena to action of man and knowledgable conservative to nature, when faced with uncertainty?"

August 20, 2014 | Unregistered Commenteraaron

Of those "100,000s of words", perhaps you could point to just the ones that provide the basis for your estimate? Or better yet, the published paper from which it is derived? If you want to claim that scientists are basing their claims on 'flimsy evidence', it doesn't look good if you provide none of your own.

On the technical point you raise about 1910-1940, we've gone over that before but I'll repeat it for anyone reading here. There is simply far more information about the more modern period. Now, we have ocean heat content data, we have stratospheric temperature trends, we have less uncertain solar trends and better (though not perfect) aerosol emission inventories. So it is should be obvious that attributions for a period that has less data, and is shorter (a 30 year period, ~half the length of 1950 to 2012 and so with a relatively higher importance for internal variability), are going to be less certain. And if you want to pick a time in the 9th C AD, that will be even more uncertain too. It just makes no sense to say that you can do attribution for one case because another situation with less information is uncertain.

You can do better than this flimsy logic.(I would have said "should do better" - but that would be advocacy).

August 20, 2014 | Unregistered CommenterGavin

==> ". If half the population can't be bothered to vote, does it make sense to say that their views on climate change are determined by their political views? "

Evidence shows a very strong association, in the U.S. at least, between views on climate change and political (or "world view") orientation. Understanding that correlation doesn't equal causation, then the question is what might be causal.

Since most people in the U.S. don't know very much about the science itself, arguably not enough to weigh the validity of the respective scientific arguments, and aren't likely to possess the technical skills needed to evaluate that evidence even if they did have the knowledge, then the question remains why would their be such a strong association?

I'm not in a position to speak for Dan, but my understanding? of the evidence he presents is not that view on climate change are determined by political viewpoints, but that views on climate change are largely the result of how group identification influences how people weigh evidence. I would add that perhaps, political views and views on climate change result from the same causal mechanism, as opposed to one (political views) causing the other (views on climate change).

I'm curious - what would you offer as explanation for why surveys of opinion in the U.S. seems to show that (1) high %'s of the public have a definitive view one way or the other (about the potential risk posed by ACO2), (2) relatively large #'s (in particular people who identify with the Tea Party) think that they are well-informed on the subject and need no more information than they already have to evaluate the science, (3) opinions are associated with political (or "world view") orientation, and (4) why identity-aggressive and identity-defensive behaviors are so ubiquitous (from both sides) in discussion of climate change?

August 20, 2014 | Unregistered CommenterJoshua

"Put aside whether the "knowing disbelief" issue is posed by the data on OCSI .... What do you make of Everhard & Hameed's Pakinstani Dr? He thinks we (for being the confused people the clever interviewer is speaking for) are obtuse. I have this feeling that he -- someone in a society that has a long way to go to make the transition to being a secular liberal democratic market state -- gets something that we, as the lucky inhabitants of such states, don't."

I'm not sure what to make of the doctor, because I don't think we've got a complete description of the distinction the doctor is making. I'm not sure that there's necessarily a contradiction either. Evolutionary theory implies a set of facts about genes and biochemical processes that are useful in oncology. But for those biochemical facts to be true does not imply that evolutionary theory is true.

However, I recognise in general that people are very good at believing several mutually incompatible things at once - it's actually a core mechanism of human intelligence. The AI people call it 'framing', in which knowledge is divided into separate contexts or compartments - each one is a distinct model of the world, what entities are in it, and the way it works. One of the problems with building AI is that if you try to construct a single self-consistent model of the world, it keeps running in to these conflicts with the way people do things. Humans flip from one model to another, picking whichever seems most useful for a given mental task, and then smoothly shifting to another incompatible one, often without even realising it.

The philosophy of science calls them 'paradigms'. A classic example is Newtonian physics. Ask a modern physicist to solve a simple problem in mechanics, and they'll very likely use the Newtonian paradigm. While they are doing so, they 'believe in' Newtonian mechanics - there's no conscious simulation or approximation going on. But if you ask them straight out whether Newtonian physics is true, they'll say no.

Or for perhaps a more familiar example, consider the 'flat Earth' approximation. When navigating around town, you think of travelling one mile north followed by one mile east as getting to exactly the same place as one mile east followed by one mile north. Mentally, you use a flat geometry, and you're not consciously thinking of it as an approximation. While you're doing it, that's how you know the world works. But if I ask you outright whether the Earth is flat, you will of course say no. And if I ask you then whether the two routes lead to the same place, you'll likewise say no, because you've shifted to a different mental model in which it isn't so.

People do this all the time without realising. In science, because consistency and precision is so important, we have to some degree identified and delineated these distinct models, and are aware of them. But we do it in everyday life too, and have no need there to keep track of them. As a result, we don't see the contrasts and conflicts, and so likely think we have only one belief, and assume that we follow logical inferences through, so if we believe X, and X implies Y, it is presumed we must believe Y as well. When it becomes apparent that people don't, we figure they must be irrational or illogical somehow, and wonder how they ever cope.

When we understand that knowledge and belief isn't singular, but is actually a complex combination of different models, all partially distinct from one another, we realise that all attempts to determine what a person 'believes' as a single proposition are doomed. It depends what frame they're working in, and they can believe one thing one moment and the opposite the next. Nor are they necessarily being illogical or irrational in doing so. And scientists, contrary to what one might expect from their reputation for strict logical consistency, are especially adept at it - as they often need to switch mental toolkits to deal with difficult problems.

It's also the way suspension of disbelief works when reading fiction. You immerse yourself into the fictional world, building a mental model in which the fictional events and relationships are 'true', to the extent that you can (temporarily) completely forget the real world and that the book you're reading is fiction. It's part of the way the human mind works.

And if you allow for the possibility that people are shifting between different mental toolkits to answer different questions, depending on context, it's possible to see how you might get different answers depending on the subject, just as you'll get different answers to physics questions if you ask in a Newtonian framework or a relativistic one. In different social contexts (like 'us' versus 'them') you will make allowances to a different degree. Both positions are 'right' in their own context.

It's a hypothesis, anyway.

"BTW, as I adverted to in one of my last comments, the "I ♥ IRT" post started out as a response to your incredulity at my statement that a smart high school student & Sir Freddie "Mercury" Hoyle would score the same on OSI. Maybe you can see why?"

I'm not sure I do. I feel no incredulity that a high school student and Fred Hoyle could score the same on your OSI test, any more than I'm incredulous that a tree might show the same low tree ring growth in a scorching hot year as in a freezing cold one. What I was arguing with was the position that the former question is measuring scientific knowledge, just as I'd take issue with the proposition that tree ring widths are measuring temperature. There's a relationship between them, but it's not identity. And even if there are a lot more high school students than Fred Hoyle's, so the correlation is almost all one way, they're still not measuring the same thing.



"On the other hand, the attribution statements in AR4 and AR5 are based on multiple studies, allow for uncertainties in solar forcing, and have estimated uncertainties that rule out <50% contribution at least at the 10% level."

"The approaches used in detection and attribution research described above cannot fully account for all uncertainties, and thus ultimately expert judgement is required to give a calibrated assessment of whether a specific cause is responsible for a given climate change."

The AR4 attribution statement, at least, was not founded on a quantified analysis of the uncertainty. Attribution requires validated models of climate, independently shown to be able to make accurate predictions (and of all components of the climate state, not just of a carefully selected few). As the IPCC says: "Both detection and attribution require knowledge of the internal climate variability on the time scales considered, usually decades or longer." So far as I know, that hasn't been demonstrated.

There's a big gap between 'the best we can do' and 'demonstrated to a calculated 90% confidence'.



"The impartial and unadulterated scientific evidence gathered thus far, ..."

"Surely, you are aware that the consensus view of the impact of ACO2 is ..."

Why the change from one to the other?



"The way to find out "what's going on in their heads" is of course to ask them!"

:-) That's something I've been telling Dan for ages! Happy to see someone else with the same view.

August 20, 2014 | Unregistered CommenterNiV

Thanks for the links to your other interesting posts! I’ve read some of them before, but there’s some good points there I’d forgotten.

”1. No, I'm not convinced that one can infer the state of the scientific evidence from whether people high in science comprehension converge. “

Actually, I wasn’t suggesting that you could infer the state of the scientific evidence from your result!

Instead, I was suggesting that the answer your participants gave specifically to the GW causality question [i.e., “(a) mostly man-made” or “(b) mostly natural”] is mostly a result of their political beliefs, and not based on scientific evidence.

That is, amongst the high OCSI scorers, for 70-80% the answer to that particular question depended on their political beliefs... and not their scientific knowledge (as many would have assumed).

In other words, your study might not tell us what “the scientific evidence” is, but it could tell us “how people interpret the scientific evidence”. Do you see what I mean?


The divergence between high OCSI Liberal Democrats & Conservative Republicans on this question is not necessarily a contradiction or puzzle.

I don’t know how much you’ve researched the GW causality question, but there is actually surprisingly little scientific evidence one way or the other.

Before the “mostly man-made” supporters start giving out to me about this claim, let me quickly clarify...

Yes, it’s true that there are a lot of “attribution studies” based on Global Climate Models (GCMs) which say the answer is (a). So, if you believe that the GCMs are reliable/accurate, then you might confidently claim “the scientific evidence says (a)”.

However, if you believe that the GCMs are unreliable/inaccurate, then the remaining “scientific evidence” for (a) is surprisingly flimsy and/or ambiguous. Sceptics would argue that there are many reasons to doubt the reliability of the GCMs, e.g., “the pause”, “the missing hotspot”, “the 1940s blip”, etc.

A second piece of “scientific evidence” often cited in support of (a) is the “hockey stick” studies. However, as NiV has pointed out above, sceptics would argue that there are many serious errors/flaws in these studies, e.g., the over-reliance on Yamal and/or bristlecones, the “divergence problem”, the “convergence problem”, the failure of sensitivity experiments involving proxy substitution, etc.

Obviously, all of these arguments have been controversial, and I appreciate that a lot of people here have very strong opinions on many of these points (myself included!).
However, for the purposes of this discussion, I don’t think we need to get into a debate over who is “right” or “wrong” in each case. We’re talking about why some people chose (a) as the answer and others chose (b) as the answer. Do we agree?

With that in mind, I’ll make these two suggestions:
i) Most people who are aware of the above technical debates would probably have a high OCSI
ii) Depending on their views on these technical debates, they could – with a good understanding of the scientific evidence - justifiably answer either (a) or (b)

This, I think, is part of the answer to your puzzle. In terms of the available scientific evidence, you can confidently claim either answer to be “right” (and simultaneously ridicule people who choose the other answer! ;) ). It simply comes down to your interpretation of the various arguments mentioned above,

e.g., Do you believe the GCMs are reliable or not? Do you believe “the 1940s blip” is just a minor “blip” (possibly due to some non-climatic biases), or does it show that natural variability has been seriously underestimated? Do you think “the hiatus” shows an unusual “lack of global warming”, or do you think, “but, it’s still the hottest decade on record”? Are claims that “the hiatus” can be explained by unnoticed deep ocean heating an example of “unproven ad hoc speculation”, or are they “a consequence of simple physics”?

These are all questions to which different people all with a strong knowledge of climate science could have different answers to. How you answer those questions could easily change your answer to the “mostly man-made” vs “mostly natural” question. As a result, the (a) vs (b) question can be answered either way depending on how you interpret the scientific evidence.

In this context, to me, it is interesting that apparently 70-80% of your high OCSI scorers answer this scientifically-ambivalent question based on their political views, rather than for scientific reasons.

You mentioned to @Jelte the possibility that,

They might well converge on conclusion that evidence supports not firm conclusions-- when the evidence is indecisive, it is biased to default to the view that it supports one's political predispositions!

It seems that this is indeed the case here! This would probably be a surprising result for those who believe that the answer to this key question is “obvious” from the scientific evidence.

3. I don't myself believe that the data I'm representing can tell us anything about how professional scientists reason.

Agreed. But, professional scientists are people too (!). If high OCSI scores introduce a strong tendency for Liberal Democrats to answer “mostly man-made” and for Conservative Republicans to answer “mostly natural”, then this tendency should also be present amongst practicing climate scientists (in the US at least). After all, presumably most practicing climate scientists would score highly on your OCSI tests, right?

We might have thought that as OCSI increases the answers would become increasingly science-based. If we assume practicing climate scientists have very high OCSI scores (seems reasonable, no?), this would imply that their answers will be the most science-based of all! However, as you point out, ”the evidence doesn't seem to fit that hypothesis”. It seems as OCSI increases, the divergence increases!

With this in mind, if the Rothman et al., 2005 findings are at all representative of the political views of U.S.-based climate scientists, this would introduce a significant “mostly man-made” bias into the average “scientific consensus” among the U.S. climate science community. That would be an interesting result.

P.S. I’m not in the U.S., but I’d probably be a high-scoring OCSI liberal who’d answer (b).

August 20, 2014 | Unregistered CommenterRonan Connolly

NiV, I'm well aware there is an element of expert assessment in assigning confidence to the attribution statements, I discuss it clearly in the 2nd RC piece I linked to above. The IPCC assessed confidence levels are substantively looser than the calculated confidence levels for precisely that reason. You and Judith, as I said above, are free to assume that nobody knows anything and downweight the calculated assessments as much as you want. However, if you want to convince anyone else that is sensible, you need to provide some actual positive evidence that the structural uncertainties are much larger than claimed. You could do this via a different attribution framework, different kinds of models (which I'm sure you agree are required in any attribution effort), or providing evidence that the standard approaches give erroneous answers in known situations etc. However, without that, you are only left with your rather unconvincing (but immovable) Bayesian prior.

August 20, 2014 | Unregistered CommenterGavin

"However, if you want to convince anyone else that is sensible, you need to provide some actual positive evidence that the structural uncertainties are much larger than claimed"

This is reversing the normal burden of proof in science. *You* have to provide positive evidence that the structural uncertainties are *not* much larger than claimed before you can make that claim. If you're going to claim a quantified numerical uncertainty, like 90%, you need to show and justify *every step* of the calculation.

Otherwise, it's not science, it's opinion. And while everyone is certainly entitled to their opinion, it's a more dubious behaviour for people to claim their quantitatively and objectively unfounded opinion to be science.

August 20, 2014 | Unregistered CommenterNiV


For sure, the science communication problem is same no matter who one assumes is right. I assume solution doesn't depend on that either -- or at least can't see why it would. Need to counteract whatever it is that interferes with the usual convergence of reasoning people on best available evidence.

August 20, 2014 | Registered CommenterDan Kahan

NiV, Sorry, you have the story backwards. People have of course looked at whether models in general underestimate internal variability (they don't appear to), and whether the attribution is robust to the variations in model skill (it is) etc.. See or for instance. You can still always appeal to the unknown unknowns to save your preconceived position, but that gets increasingly untenable since you not only have to assume that something else is causal, but also that it cancels out all the expected impacts of anthropogenic forcings. What Dan is puzzling over is exactly why people cling to such increasingly implausible positions on issues with political salience when the mainstream science has moved on.

August 20, 2014 | Unregistered CommenterGavin

"People have of course looked at whether models in general underestimate internal variability (they don't appear to), and whether the attribution is robust to the variations in model skill (it is) etc"

So are you saying that, contrary to the IPCC's position, all the uncertainties are quantified?

"In this method, the reliability of a model ensemble is evaluated from the point of view of whether the observations can be regarded as being sampled from the ensemble."

That would be useful, so long as you can first show that the ensemble has not been selected to fit the observations. The verification has to be independent.

"Because of the pronounced effect of interannual noise on decadal trends, a multi-model ensemble of anthropogenically-forced simulations displays many 10-year periods with little warming. A single decade of observational TLT data is therefore inadequate for identifying a slowly evolving anthropogenic warming signal. Our results show that temperature records of at least 17 years in length are required for identifying human effects on global-mean tropospheric temperature."

Excellent! This is the first step in a verification of the models. The bounds of the distribution of internal variability have been identified, enabling a prediction. So long as the period of little warming of the TLT data remains less than 17 years, the models remain a candidate. As soon as the data exceed 17 years of zero trend, the models are falsified. This is precisely the sort of quantitative argument you need.

You now need to work out how long a period has to pass with no 17+ year zero-trend periods for you to be fairly certain that they're not going to. (e.g. a statement of the form: "if n independent 17 year periods pass with no zero-trend cases, the probability of such periods must be less than p". From memory, you need about 3-5 times the threshold mean period between events.) And then, if such an interval *does* pass, you will be able to *start* using the models to make decisions.

Actually, that's pretty funny, considering the recent record. Would you agree that 17 years of zero trend falsifies the models?

"You can still always appeal to the unknown unknowns to save your preconceived position"

That's not my preconceived position.

My view is that yes, about half the observed warming is likely to be anthropogenic on general theoretical grounds, absent any good reason to think otherwise, but that this has not been demonstrated quantitatively, let alone at a 90% level, and the evidence for/against it is very weak. I consider it plausible/informed conjecture, rather like supersymmetry is in high energy physics.

It's a respectable conjecture, but it remains conjecture.

August 20, 2014 | Unregistered CommenterNiV

NiV, I'll ask you the same as I asked Judith - on what do you base your confidence that the attribution for the last ~50 years is 'about half' to human activities? (I ask because I am genuinely unclear of what modeling framework you can be using that is so superior to the ones that the mainstream scientists working on this use).

As for your other points... you might want to think about it more carefully: On mismatches between models and observations, Reconciling warming trends.

August 20, 2014 | Unregistered CommenterGavin

I read something a little while ago (don't remember where) which claimed conservative have a "negativity bias". They worry more about loss and safety. [Which reminds me of a piece many years ago at overcoming bias that showed that people who are depressed think more rationally;)]

It was suggested that this should make them more accepting anti-global warming policy contrary to polls.

I think what is happening more is that the anxious, conservative thinkers instead are used to thinking about threats, prioritizing threats, determining whether it is feasible deter a threat, and may be more prepared to deal with uncertainty and threats. So, they are less likely to take a costly action that is unlikely to change actual risk, better to prepare.

Anyway, perhaps this "negativity" bias is at play. Conservatives seeing a limit as to how much man is capable of affecting a massive and complex system. Changes are only marginal and eventually dampening effects dominate. And liberals have a "social" bias, seeing human action having infinite potential to impact any type of system.

So, when conservatives think with lots of knowledge, they see small relationships with minor compounding where dampening effects eventually dominate in the physical world. Liberals, being more social, may be more biased toward belief in positive feedbacks which are common in the social world.

August 20, 2014 | Unregistered Commenteraaron

I'm pretty much with Paul Matthews here, I don't see the same head scratching contradiction here that Dan does.

In a way in fact, it is entirely to be expected. It does not follow that the more educated one is an a subject, the more likely it is that you will fall towards a consensus. That depends entirely on the definitiveness of the data. In the case of a chaotic, overwhelmingly complex system, where understanding is, being generous, incomplete, it is only to be expected that a competent observer might be able to make a wide variety of plausible scenarios from the same sets of data, and indeed that their position might be complementary to whatever other biases they hold.

I find it much more interesting to observe the amount of people that, instead of observing this type of phenomena and questioning whether this diversity of opinion could be related to the quality, or utility of our understanding of a subject, instead immediately set out to analyse how someone could possibly disagree with them!

Neither, by the way, do I hold that in necessarily follows that the consensus opinion of climate scientists can claim special rights to a position as the de facto best understanding of the climate system as a whole. There is no reason that discovering what is understood about a specialist position, or several individual specialist positions should correlate with whatever a consensus opinion of these same specialists might be.

Complex engineered systems are not arrived at by a consensus of specialists in the same way that a pencil won't result from a brain storming session between a lead miner and a lumberjack, and there are a multitude of people who, everyday, combine the knowledge of specialists into engineered products as they would combine any other sets of tools, that would actually reject any concept of duality from the outset, because they don't recognise the special weight afforded a premeditated specialist consensus.

August 20, 2014 | Unregistered CommenterJames

Gavin and Joshua (citing Kerry Emanuel) broach the relevant topic: how much risk do we want to take?

No one has mentioned that people are in general risk averse – thus the ubiquity of insurance of all kinds. Only the motivated reasoner will deny this, such as the very well published medical researcher, climate change denier and colleague of mine who when I mentioned that because people are risk averse, we might want to buy some insurance in the form of reduced carbon emissions blurted “I never buy insurance”, which I know to be untrue.

So the relevant question is really not how much stronger the evidence need to be of anthropogenic climate change, but given the non-zero risk of a very large cost if it is true, how much insurance do we want to buy in the form of emission reduction? And the answer is not zero.

And further, there is low hanging fruit so that the initial costs are relatively low.

August 20, 2014 | Unregistered CommenterHaynes

Appreciate your work Dan and the insights of the comments.

I have a question that touches on one of the foundational ideas in this discussion--that people converge on the best available scientific evidence. What happens if there is no best available scientific evidence? What if the evidence is ambiguous, sometimes contradictory, etc? How would you expect people to behave in that circumstance? I would expect them to emphasize the evidence that suits their ideology and ignore the evidence that does not. Those who have no "dog in the fight" ideologically would just tune everything out until the evidence was more clear.

Isn't this exactly what we see? And isn't this the simplest explanation for what we see? I know there is a lot out there that claims there is a clear consensus on AGW but how do we know those claims don't stem from the same motivated reasoning that causes people to line up by ideology on this issue? In a survey of members of the American Meteorological Society, 48% of the membership gave an answer other than "Yes, mostly human" to a question asking if there was global warming and what its cause was. The same study found that ideology was a stronger predictor of opinion on AGW than expertise in climate science.

Of course people can argue endlessly about how to assess the scientific evidence, and I don't want to go there. I simply want to explore the idea that 1) people usually converge on the best evidence, 2) there is no convergence on the AGW issue, and 3) therefore the simplest explanation is that there isn't actually best evidence in regards to AGW on which to converge.

August 20, 2014 | Unregistered CommenterEvan
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