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« More on the rationality of (dis)belief in evolution | Main | Does disgust drive anti-vax sentiment? Does't look like it to me . . . . »

On the rationality of (dis)belief in evolution -- new paper

More on this anon . . . .

Rationality and Belief in Human Evolution


Dan M. Kahan
Yale University

Keith E. Stanovich
University of Toronto


This paper examines two opposing theories of disbelief in evolution. One, the “bounded rationality” account, attributes disbelief to the inability of individuals to suppress the strongly held intuition that all functional systems, including living beings, originate in intentional agency. The other, the “expressive rationality” account, holds that positions on evolution arise from individuals’ tendency to form beliefs that signal their membership in and loyalty to identity-defining cultural groups. To assess the relative plausibility of these theories, the paper analyzes data on the relationship between study subjects’ beliefs in evolution, their religiosity, and their scores on the Cognitive Reflection Test (CRT), a measure of critical-reasoning proficiencies including the disposition to interrogate intuitions in light of available evidence.  Far from uniformly inclining individuals to believe in evolution, higher CRT scores magnified the division between relatively religious and relatively nonreligious study subjects.  This result was inconsistent with the bounded rationality theory, which predicts that belief in evolution should increase in tandem with CRT scores for all individuals, regardless of cultural identity.  It was more consistent with the expressive rationality theory, under which individuals of opposing cultural identities can be expected to use all the cognitive resources at their disposal to form identity-congruent beliefs. The paper discusses the implications for both the study of public controversy over evolution and the study of rationality and conflicts over scientific knowledge generally.



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Reader Comments (19)

You could just tell me to read the paper, but...

==> This result was inconsistent with the bounded rationality theory, which predicts that belief in evolution should increase in tandem with CRT scores for all individuals, regardless of cultural identity. <==

Why does bounded rationality have to be completely free from any cultural influence? Does the theory hold that it has to be all or nothing? Couldn't there be a combined effect?

Seems to me that bounded rationality reflects a natural baseline psychological instinct, the manifestation of which can be mitigated or influenced by any number of factors - including cultural identification.

For example, I think of what Michael Shermer says here:

As a personality, I like the ambiguity of science and the open-endedness. I have a high tolerance of ambiguity; not everybody does. That's one of the appealing notions of religion ... it offers a balm to ambiguity -- certain absolutes to certain questions.

or what Carl Sagan says here:

I have a tolerance for ambiguity. It's clear to me that there's some questions that humans don't have the answers to and what arrogance to imagine we have answers to all questions. Science is sometimes, I know, attacked for supposed arrogance, but I think it's the most humble occupation and discipline around. Because, instead of trying to impose our preconceptions, our predispositions on the Universe, we are open before the Universe to see what the Universe has to offer. Science is in the business of finding out what's true--to the extent that humans are capable of that--whereas a lot of these other disciplines are in the business of pretending that what feels good is true.

While those quotes don't point to cultural identification as an influence, it does point to individual variance in how a baseline intolerance for ambiguity might predict, to some degree, and not independent of cultural influence, beliefs on education. Why can't, for example, cultural orientation or tolerance for ambiguity moderate the relationship between a baseline psychological preference for bounded rationality and beliefs about evolution?

September 14, 2016 | Unregistered CommenterJoshua

er....that was supposed to be "might predict....beliefs on evolution" not "beliefs on education." Sheece.

September 14, 2016 | Unregistered CommenterJoshua

First sentence after abstract:

==> The theory of evolution is simultaneously one of the most well-established and lest popularly accepted insights of modern science. <==


September 14, 2016 | Unregistered CommenterJoshua

thanks for catching that! Proves again that 28 billion eyes are better than 4.

Yes, the paper points out that it would be ridiculous to say BRD has to take view that culture is irrelevant.

Additive effects are fine, conditional ones not

September 14, 2016 | Registered CommenterDan Kahan

In this case, I'm not sure that “bounded rationality” is very descriptive of what you seem to be talking about. It kind of suggests that the opposite group believe in evolution because their rationality is unbounded, or that their belief is for essentially rational reasons.

It could (hypothetically) instead be due to an inability of certain individuals to suppress their strongly held intuition that all scientists are always right (since the most common reason ordinary people give for believing in evolution is that "all scientists say so", presumably those who don't believe are the ones who are not subject to that delusion...). It's possible that people believe in evolution for essentially cultural reasons too. Just because they got the answer right doesn't imply that their method of getting there was therefore a rational one.

The idea that the appearance of intelligent design implies a designer is a respectable one, that was commonly held to be valid even by experts and the well-educated prior to Darwin's book. Darwin's argument that persuaded them otherwise is sophisticated and subtle. If a person does not understand that theory, because it has never been properly explained to them, then isn't the design intuition - the one held by all the experts in the subject prior to Darwin - both reasonable and rational? More so than accepting an implausible-sounding theory that they don't understand simply because the current crop of experts say so? If the last lot of pre-Darwin experts were so wrong, why, rationally, and without knowing of any other reasons to believe what they say, should we think the current lot are necessarily right?

Why isn't people accepting argumentum ad verecundiam the 'irrationality' we need a specially-named thesis to explain?

Rather than 'bounded rationality thesis', I'd call it a 'design implying designer assumption' thesis, or "designer intuition' thesis, or something like that - if that's what you think the critical distinguishing assumption is. There are plenty of other possibilities, though.

September 14, 2016 | Unregistered CommenterNiV


I'll discuss this a bit more "tomorrow," but "bounded rationality" describes the thesis we are critically testing. That position holds that disbelief is a consequence of overreliance on heuristic information processing-- the hallmark of bounded rationality (Kahneman 2003).

Yes it's weird to imply that those who believe do so b/c they are "more rational" when it is in fact well established that most evolution 'believers' couldn't pass a high school biology exam on the modern synthesis. It's clear only a small minority of those who believe or disbelieve have the education & mental acuity to understand the mechanisms of evolution. That's one of the reasons why "believe in evolution" is not considered a valid standardized science comprehension assessment question.

September 14, 2016 | Registered CommenterDan Kahan

So Dan -

I'm just starting to work through your paper...but I'm hoping you could point me to the reference that supports this statement:

This result was inconsistent with the bounded rationality theory, which predicts that belief in evolution should increase in tandem with CRT scores for all individuals, regardless of cultural identity.

September 14, 2016 | Unregistered CommenterJoshua

This is an interesting paper. After looking closely at the statistics, I have one question about the methods, and noticed one graph with mixed-up data.

Is there a way to check, in your data, whether belief in evolution is influencing religiosity? I think that could also be consistent with your results if there was a large effect. Imagine that highly religious people with high CRTs are more likely to believe in evolution than highly religious people with low CRTs-- but the ones that believe in evolution decide to become less religious as a result. Then you would see the same pattern-- high CRTs associated with belief in evolution overall, but the trend within the highly religious group would be flat due to the desertions of the evolution-believers.

A quick check to see if this could be happening would be to see if higher CRT is associated with lower religiosity. I'm not sure it can be decisively ruled out without some sort of time series (longitudinal) data. Or maybe there are other studies looking at that question that could help rule out that possibility.

The points in the graph for study 2 don't match the percentages shown on the lines. That data definitely got mixed up somehow.

September 14, 2016 | Unregistered CommenterWill May

@Will-- I don't think there's any way to figure out whether belief in evolution influences religiosity as opposed to other way 'round w/ these data, their being purely observational. For sure that's the kind of thing where inference relies a lot on theory outside the data. It is the case, though, that CRT is negatively correlated w/ religiosity.

Now on the graph, which one do you think has a glitch? Figure 2, I take it? Panel (C) or (D)? I'm think I'm not seeing the problem!

September 14, 2016 | Registered CommenterDan Kahan

@Joshua-- see discussion pp. 2, 7, 21

September 14, 2016 | Registered CommenterDan Kahan

Yes, figure 2. Panel (D) is the one where the numbers aren't matching, but that implies panel (C) has the wrong data plotted as well. I shouldn't have written "points"-- I mean the small circles representing individuals. For Study 1 and and the national sample you have high religiosity respondents on the bottom, blue=evolution, orange=creationism. But in figure 2 somehow high religiosity ended up on the top, with the colors flipped (I think that's what's going on).

September 14, 2016 | Unregistered CommenterWill May

@Will-- I screw that sort of thing up often enough that I gotta believe you are right, but I'm still not seeing the problem. Maybe you could walk me through it via Skype? Email me.

Gervais's study 2 is amazing: some 99% of above-avg-religiosity rspts & substantial majority of above-avg ones were "disbelievers." Part of explanation is that Univ of Ky undergrad sample is more religious than nat'l avg; other part, I suspect, is that the question wording is the most aggressively "anti-God" of all the "believe in evolution" formulations

September 15, 2016 | Registered CommenterDan Kahan

In my opinion,, you need a more specific term for what is being analyzed than "religiosity" . In a Kentucky sample, even at the University, I'd think you'd be biased towards a specific form of Abrahamic religious traditions, namely Evangelical Christians: And even Evangelical Christians are far from a monolithic category. History: Beginnings here: Now Less and less connection to any national organized religious group more stock in "born again" personal transformations.

September 15, 2016 | Unregistered CommenterGaythia Weis

"I'll discuss this a bit more "tomorrow," but "bounded rationality" describes the thesis we are critically testing. That position holds that disbelief is a consequence of overreliance on heuristic information processing-- the hallmark of bounded rationality (Kahneman 2003)."

My point is that *both* alternative behaviours can be explained (and often are, by diferent people) by the *same* "bounded rationality" hypothesis. Belief in evolution is explained as a consequence of overreliance on a form of heuristic information processing: blind trust in scientific dogma. Disbelief in evolution is explained as a consequence of overreliance on a form of heuristic information processing: blind trust in religious dogma. Belief is founded on "just so" stories about "survival of the species" and "survival of the fittest" without any real understanding of what these terms mean, or when they apply. (For example, explain why there are so many men, when you could almost double your rate of production of descendants by producing 95% daughters to 5% sons. From the point of view of intuitions about reproductive success, the 50% rate seems inexplicable.) Disbelief is often founded on intuitions about information and randomness and probability, which humans are likewise notorious for getting wrong (as Kahneman shows at length).

When *both* outcomes are explained by the *same* hypothesis, the hypothesis *cannot* be an explanation of the difference. It's not explained by "bounded rationality" per se, but by the specific variety of bounded rationality - whgich particular heuristics people are relying on, and why.

Kahneman says in the paper you link that his bounded rationality includes preferences as a factor in the heuristics people use.

"Slovic and his colleagues (see, e.g., Slovic et al., 2002) introduced the concept of an affect heuristic. They showed that affect (liking or disliking) is the heuristic attribute for numerous target attributes, including the evaluation of the costs and benefits of various technologies, the safe concentration of chemicals, and even the predicted economic performance of various industries. In an article aptly titled “Risk as Feelings,” Loewenstein et al. (2001) documented the related proposition that beliefs about risk are often expressions of emotion."

So assuming people "like" conclusions that agree with their political preferences and cultural identity, we would already predict political/cultural differences under the BRT hypothesis. Those who 'like' evolution and the worldview it supports will believe in it, irrespective of the reasons. When the same outcome is predicted by both hypotheses, and when both outcomes are predicted by one of the hypotheses, the likelihood ratios get messed up.

"Bounded rationality" as Kahneman defines it is too broad a hypothesis for this sort of distinction. It predicts everything, and so explains nothing. It's a general and generic description of all human behaviour, and so is equally applicable to everyone.

The only "rational" position to take in the evolution debate, unless you do actually understand Darwin's theory and the evidence for it in some detail, is agnosticism. As a layman you simply don't know, can't know, and either of the other positions has to be based on faith and unreliable heuristics.

September 16, 2016 | Unregistered CommenterNiV

OOOOOOooooooooooohhhhhhhh, I totally misinterpreted the graph. Totally misunderstood the colors and everything. Never mind, sorry about that. It's good!

September 16, 2016 | Unregistered CommenterWill May

@Will-- then the graph needs to be redone; it shouldn't fool people. Naughty, naughty graphic!

September 16, 2016 | Registered CommenterDan Kahan


Well, like I said, it's someone else's hypothesis & we reject it.

But our own is that the more cognitively proficient the more one will either believe or disbelieve conditional on what sort of person one is. The evidence we present supports that. The evidence deserves to be taken only as seriously as it deserves to be taken. But what you need to address is what it would mean for your position if what we found does indeed turn out to be the best view of how beliefs/nonbeliefs are distributed. We have a section *just for you* on why one can't argue against the rationality of the answers that the most rational rspts supply!

September 16, 2016 | Registered CommenterDan Kahan

"But what you need to address is what it would mean for your position if what we found does indeed turn out to be the best view of how beliefs/nonbeliefs are distributed."

The issue is with the following statement: "This result was inconsistent with the bounded rationality theory, which predicts that belief in evolution should increase in tandem with CRT scores for all individuals, regardless of cultural identity."

I don't think this is correct, because it doesn't specify in what way rationality is bounded.

Like I said, the only "rational" position on evolution for the vast majority of the general public, without the scientific training to decide for themselves, is agnosticism. Belief in the absence of valid reasons is irrational - and is mostly down to their over-reliance on the 'Argument from Authority' fallacy/heuristic. CRT might intuitively be expected to counter that tendency - inclining people to critically examine their own and their authorities' assumptions. My version of the Bounded Rationality Thesis therefore predicts belief in evolution should decrease in tandem with CRT!

We have managed to come to opposite predictions from the 'same' hypothesis! The point is that they're not actually the same, because I've considered only the 'Argument from Authority' heuristic, and you've only included the 'Paley's Watchmaker' heuristic. If we follow Kahneman, and look instead a Slovic's "affect heuristic", we would predict that people will be biased towards the hypotheses they like the most, the ones they feel most comfortable with. Evolution believers are more comfortable with the scientific consensus and so more willing to rely on authority than they would be if the authorities came to conclusions they opposed. Vice versa for disbelievers. It's not a conflict between BRT and something else, but between two (or more) different varieties of the BRT.

As I've said before, my position is that people do not simply pick positions based on identity, but instead rationalise their conclusions using heuristics of varying fidelity and sophistication, and have a tendency to keep searching longer, using more sophisticated heuristics when the simpler heuristics they start with are giving answers they don't believe.

That's why decreasing CRT decreases polarisation. People without high scientific literacy are just as motivated by identity and culture, but are unable to generate the counter-arguments they need to avoid the conclusions they don't like.

Under this hypothesis, it's not that people are more rational with regard to accepting conclusions they like - they're actually more rational (when capable of it) when rejecting conclusions they don't like. They're not rejecting rational argument entirely and instead holding positions purely because of their identity and culture - they're instead applying their rationality selectively depending on their identity and culture. Everyone always has rational reasons for their own beliefs - so they believe. But *all* such 'reasons' are based on heuristics, models, and assumptions (even in pure mathematics). Rationality in this sense lies on a spectrum.

"We have a section *just for you* on why one can't argue against the rationality of the answers that the most rational rspts supply!"

which section? I'm guessing section 4? Maybe this bit..? "To be sure, BRD needn’t be viewed as making the absurd prediction that religiosity is irrelevant to endorsement of evolution; but when it becomes clear that CRT is irrelevant for predicting beliefs among individuals who harbor a religious cultural identity, BRD itself becomes absurd. Having shown themselves to be “better able to analytically control their thoughts” (Gervais, 2015, p. 321), religious individuals who score highest on the CRT remain no “more likely to eventually endorse evolution’s role in the diversity of life and the origin of our species” (ibid.) than those who have evinced the lowest capacity to stifle reliance on intuitions. This result implies that it simply incorrect to attribute conflict over evolution to overreliance on heuristic processing."

Maybe. There are two sets of invalid heuristics to overcome: blind faith in scientific dogma inclining one to unjustified belief, and blind faith in religious dogma inclining one to unjustified disbelief. Suppose that in the very religious both are overcome by CRT in equal measure - the number who are persuaded of evolution by rejection of arguments from religious authority equals the number who are more persuaded against by their greater ability to find arguments for rejection of scientific authority. For the least religious, the balance between the two effects is different. (I'm assuming the completely non-religious are lost in the data - even for the least religious group only 82% rejected theistic guidance in human evolution.)

It's hard to say.

By the way, I really liked this bit:
"It is, we’ve explained, individually rational, in an expressive sense, for persons to be guided by the habits of mind that conform their beliefs on culturally disputed issues to ones that predominate in their group. But when all individuals do this all at once, the results can be collectively disastrous."

For example, everyone following the "scientific consensus"? :-)

September 17, 2016 | Unregistered CommenterNiV

@NiV-- that plus the discussion of Spearman’s positive manifold, which addresses the signficance to give to covariances among standardized assessment items when assessing the validity of any one of them

September 19, 2016 | Registered CommenterDan Kahan

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