About Rationally Speaking

Rationally Speaking is a blog maintained by Prof. Massimo Pigliucci, a philosopher at the City University of New York. The blog reflects the Enlightenment figure Marquis de Condorcet's idea of what a public intellectual (yes, we know, that's such a bad word) ought to be: someone who devotes himself to "the tracking down of prejudices in the hiding places where priests, the schools, the government, and all long-established institutions had gathered and protected them." You're welcome. Please notice that the contents of this blog can be reprinted under the standard Creative Commons license.

Tuesday, June 28, 2011

Bad reasoning about reasoning

by Massimo Pigliucci
A recent paper on the evolutionary psychology of reasoning has made mainstream news, with extensive coverage by the New York Times, among others. Too bad the “research” is badly flawed, and the lesson drawn by Patricia Cohen’s commentary in the Times is precisely the wrong one.
Readers of this blog and listeners to our podcast know very well that I tend to be pretty skeptical of evolutionary psychology in general. The reason isn’t because there is anything inherently wrong about thinking that (some) human behavioral traits evolved in response to natural selection. That’s just an uncontroversial consequence of standard evolutionary theory. The devil, rather, is in the details: it is next to impossible to test specific evopsych hypotheses because the crucial data are often missing. The fossil record hardly helps (if we are talking about behavior), there are precious few closely related species for comparison (and they are not at all that closely related), and the current ecological-social environment is very different from the “ERE,” the Evolutionarily Relevant Environment (which means that measuring selection on a given trait in today’s humans is pretty much irrelevant).
That said, I was curious about Hugo Mercier and Dan Sperber’s paper, “Why do humans reason? Arguments for an argumentative theory,” published in Behavioral and Brain Sciences (volume 34, pp. 57-111, 2011), which is accompanied by an extensive peer commentary. My curiosity was piqued in particular because of the Times’ headline from the June 14 article: “Reason Seen More as Weapon Than Path to Truth.” Oh crap, I thought.
Mercier and Sperber’s basic argument is that reason did not evolve to allow us to seek truth, but rather to win arguments with our fellow human beings. We are natural lawyers, not natural philosophers. This, according to them, explains why people are so bad at reasoning, for instance why we tend to fall for basic mistakes such as the well known confirmation bias — a tendency to seek evidence in favor of one’s position and discount contrary evidence that is well on display in politics and pseudoscience. (One could immediately raise the obvious “so what?” objection to all of this: language possibly evolved to coordinate hunting and gossip about your neighbor. That doesn’t mean we can’t take writing and speaking courses and dramatically improve on our given endowment, natural selection be damned.)
The first substantive thing to notice about the paper is that there isn’t a single new datum to back up the central hypothesis. It is one (long) argument in which the authors review well known cognitive science literature and simply apply evopsych speculation to it. If that’s the way to get into the New York Times, I better increase my speculation quotient.
The second thing that ought to strike the reader as strange is the very idea that one can meaningfully talk about “reasoning” as if it were a well defined biological trait, like having a prehensile tail. Reasoning is a complex activity that draws on a variety of brain structures that certainly predated the “evolution” of reasoning itself, which means that — at best — natural selection has co-opted bits and pieces of those structures as in a sort of Rube Goldberg contraption. That would account for the “puzzling” fact that human reasoning is so prone to failure.
Moreover, as commentator Darcia Narvaez (University of Notre Dame) put it in the Times article, “reasoning is something that develops from experience” and language — which is necessary to communicate our reasoning (and therefore for arguing) — is a very late comer in human evolution. The unspoken corollary being that therefore there has been comparatively little time for natural selection to have much of an impact.
Things get even more odd if one begins to pick apart the Mercier and Sperber paper. They start out by saying that “we outline an approach to reasoning based on the idea that the primary function for which it evolved is the production and evaluation of arguments in communication.” But this assumes, again, that “reasoning” is a sufficiently coherent biological trait that historically took on a well defined “function,” none of which is at all uncontroversial or well established.
But the real problem with the paper comes near the end, when the authors have to admit that human reasoning actually works pretty darn well — when it is used in a group context and people are motivated to seek the truth (as opposed to an individual context, or when people are motivated by personal gain). For instance:
“In group reasoning experiments where participants share an interest in discovering the right answer, it has been shown that truth wins ... In these group tasks, individual participants come up with and propose to the group the same inappropriate answers that they come up with in individual testing. The group success is due to, first and foremost, the filtering of a variety of solutions, achieved through evaluation. ... Reasoning is responsible for some of the greatest achievements of human thought in the epistemic and moral domains. This is undeniably true, but the achievements involved are all collective and result from interactions over many generations.”
No kidding. There is absolutely nothing new here. For instance, sociologist and philosopher Helen Longino has long pointed out that science itself works because it is a social process of continuous peer review, where individual biases are countered by other individual biases (and by the existence of an actual physical world that doesn’t care about human biases). So it turns out that it isn’t that humans are bad at reasoning, but rather that reasoning itself is an inherent social activity, that works well in a group context. Is this a different phenomenon from individual reasoning? Is this too the result of natural selection? At the group level, perhaps? Mercier and Sperber do not say.
There also seems to be a basic logical flaw in the authors’ argument. When, for instance, they say: “in most discussions, rather than looking for flaws in our own arguments, it is easier to let the other person find them and only then adjust our arguments, if necessary.” That may very well be true, but wouldn’t that select for better and better ways to spot bad arguments in other people’s reasoning? And wouldn’t that lead to the evolution of near-perfect logicians? You see how easy it is to spin evopsych scenarios?
Moreover, there is a question of how necessary the invocation of a new theory actually is in this context. Again Mercier and Sperber: “True, most of [our] predictions can be derived from other theories ... In our discussion of motivated reasoning and of reason-based choice, not only did we converge in our prediction with existing theories, but we also extensively borrowed from them.” Oh, so other explanations are both possible and viable, and there are no new data to discriminate among the offerings. Do I smell pseudoscience here?
Finally, a comment on the way these “findings” have been reported. While the Times article is actually a pretty good reflection of the paper itself (and of the peer commentaries thereof), the tone and particularly the title suggest that philosophers, logicians and the like have been misguided in their insistence on the power of human reason. But if anything Mercier and Sperber’s theory (or, more seriously, the vast literature on cognitive biases) argues that we need philosophy, logic, science and critical thinking all the more — as a counter to the natural tendency of humanity to think badly. When commenting on the fact that a relatively small percentage of people is capable of sound reasoning (for instance in the famous Wason selection task — which I teach in my critical reasoning course), the authors say: “this is an acquired skill and involves exercising some imperfect control over a natural disposition that spontaneously pulls in a different direction.” Right, and those skills are honed precisely by studying and by exposing people to constant (as rational as we can muster) dialogue. I wonder why that little observation didn’t make it into the Times article.


  1. Massimo, I can't comment about this paper but regarding evolutionary psychology I suggest reading the blog of Robert Kurzban. For example, this post shows how people are willing to infer about adaptations for any other animal, but not humans even thought the same logic and research appraoched are applied:


    I find it very hypocritical to accept one and not the other just because humans are involved.

  2. Your summary seems odd, though I confess I haven't made it to the end of their paper yet--

    "Mercier and Sperber’s basic argument is that reason did not evolve to allow us to seek truth, but rather to win arguments with our fellow human beings."

    They're main point is that reasoning is not primarily a solo business, but functions to facilitate communication between individuals. The way you put it implies they think communication is about winning, *not* truth, but that might be a false dichotomy, on their view. Communication might be seen as (ultimately, in complex ways--long story needed) advancing truth, just in a different way from individual cognition.

    Also--why should this article be faulted for lack of new data? They do use a lot of existing data, and this kind of thing is very common. A similar article is Haidt's very influential and interesting "emotional dog" paper.

  3. First off, you appear to be misunderstanding a fundamental component of evo psych (in this post and in your podcast), and that is the logic of adaptationism. Evo psych does not generate hypotheses about the evolutionary history of organisms, which may well be unfalsifiable in certain contexts, but rather hypotheses about evolved function. Functional hypotheses can quite easily be adjudicated with experiments. The alternative hypothesis, saying that something is an evolutionary accident or “kluge,” is what is actually unfalsifiable.

    "The first substantive thing to notice about the paper is that there isn’t a single new datum to back up the central hypothesis."

    That's not the point. They sought to provide an explanation, not a hypothesis, for a cognitive phenomenon. And it is undoubtedly a compelling one: the explanation is parsimonious, has a broad explanatory scope, unifies disparate phenomena, fits with what we know about evolution (i.e. traits as complex and nonrandomly organized as human reasoning tend to have functions), is precise (indeed, far more precise than “it develops according to experience”), and it yields many exciting new predictions (e.g. will people learn more efficiently if the content is framed in an argumentative context?).

    "But this assumes, again, that “reasoning” is a sufficiently coherent biological trait..."

    What else would reasoning be if not biological? A cloud of pixie-dust?

    "...wouldn’t that select for better and better ways to spot bad arguments in other people’s reasoning?"

    Yes, and indeed people are better at spotting flaws in their opponent's arguments than they are in spotting flaws in their own.

    "And wouldn’t that lead to the evolution of near-perfect logicians?"

    No more than an arms race between predator and prey would lead to the evolution of rodents that travel the speed of light.

    "You see how easy it is to spin evopsych scenarios?"

    It is easy to spin any kind of scenario, whether it be a sociocultural scenario, a "kluge" scenario, or a cartesian mind-dust scenario. The question is not how easy it is to generate a theory; the question is how well that theory fits the evidence. This theory, I think, fits the evidence rather well.

  4. @Gil

    I'm quite certain Massimo is not arguing that we cannot or should not make inferences regarding adaptations in humans. Evolutionary claims regarding cognitive abilities suffer from limitations in evidence that structural adaptions do not. One must be therefore be more careful when proposing an evolutionary mechanism for the development of a given cognitive trait.

    @pin pin

    Can you please provide an example as to how this hypothesis could be tested? Specifically, I'm curious as to how this can be tested from an evolutionary standpoint.

    I'm also a little confused at your statement that, "they sought to provide an explanation, not a hypothesis. . ." What's the difference?

    Furthermore, while it may be true that we are better at arguing than finding T(t)ruth, it's a big to jump to how this came to be about from an evolutionary standpoint.

    "But this assumes, again, that "reasoning" is a sufficiently coherent biological trait. . ."

    The emphasis is on "sufficiently coherent" not "biological." I agree with Massimo that it's more than a bit simplistic to speak of "reason" as a discrete function upon which selective pressure can act.

    Finally, the reason it's easy to spin evopsych is that we only have one data point, viz. what is currently observable. For "reason" we can only go as far back as written records exist and I doubt (though I may be wrong as I'm no anthropologist) that most of the pre-Classical records give us much insight in whatever we might call "human reason." So how exactly can we figure out how our current reason evolved?

  5. Gil,

    It's not a matter of hypocrisy, it's the fact that adaptive hypotheses are much more difficult to test with humans than with other animals, as I briefly pointed out in the post. A much more rigorous critique of evopsych can be found in Making Sense of Evolution, which I co-authored with Jonathan Kaplan.


    Indeed, the two hypotheses aren't mutually exclusive, but neither can actually be tested. My point about lack of new data is that this is typical modus operandi in evopsych: much speculation, little hard evidence. As for Haidt, if you search this blog you will quickly discover that my opinion of his research isn't exactly stellar.


    Please, I can assure you that I understand the logic of adaptationism perfectly well. I'm an evolutionary biologist by training. Interesting distinction you make between an explanation and an hypothesis: so in science we can get away with explaining things without actually testing?

    And no, I wasn't talking about pixie dust. If you read my post carefully you'll find that I said that it is hard to imagine "reasoning" as a sufficiently simple and coherent trait on which natural selection could have acted directly. More likely it is a jumble of different cognitive traits that evolved in a complex manner. Not to mention that reasoning, just like language, is heavily influenced by culture.

    Predators can't evolve to run to the speed of light because of a physical barrier, but human reasoning is demonstrably so prone to bias and fallacies that it looks to me more like the result of a jumble of different processes than of a neat process of selection.

    And in science the question is most decidedly not whether an explanation fits the evidence, because it is notoriously too easy to produce just so stories that fit. The crucial question is how we can test the hypothesis.

  6. Massimo and SioFox, what I was trying to say is that the logic for identyfing adaptations should be the same of humans and other animals. Would you say the we can't learn about chimps just because there are no other species that are close to them present? Why is it ok for biologists to offer function for behaviorals of any animals (such as the sloth in the Coyne post that RK commented) and no one say it's a "just so story" but when ev psychs use the same logic they are immediately attacked and the science is undermined? I just don't find it very consistent or nor logical.

  7. Massimo--

    Have you actually objected to Haidt's research, or just to his popular articles?

  8. The argumentative theory is non-falsifiable. Any successful argument against it only serves to prove it paradoxically.

  9. Gil,

    There is nothing wrong with the logic (as I pointed out in the post), it's that humans are particularly bad empirical subjects when it comes to the evolution of behavioral traits. At least in chimpanzees one could measure ongoing natural selection (though with difficulty), but in humans that's irrelevant, because the modern physical and social environment is very different from the evolutionarily relevant one.


    I like some of Haidt's research, but disagree with some of his conclusions, and I think some of his stuff is pretty low quality. But that's another post.

  10. Gil, I agree the that *logic* should be the same of humans and other animals. I think one of the key points of the article to which you link is the supposition that Coyne makes regarding whether or not shitting on the ground is learned v. genetic. He makes the assumption that it is primarily genetic. I'm no zoologist so I'd actually like to see evidence supporting that assumption. It should be experimentally straight forward to test this. If it was demonstrated that ground-pooping was learned instead of primarily genetically based I wonder if he would change his tune?

    I'd also like to see the same evidence for whether "reasoning" is an inherently genetic function or to what extent learning influences "reason." I agree with Massimo that it is more likely that "reasoning" represents a collection of cognitive modules rather than a coherent, independent trait.

    There are cognitive functions that lend themselves better to evopsych explanations than others (some heuristics, some neonatal behaviors, etc). The minute you start talking about ill-defined concepts such as "reason" you can start to expect the sloth shit to start flying.

  11. Massimo, I agree that is difficult but in other species we don't always measure ongoing selection. Many times biologists infer adaptations solely based on behavior without knowing anything about the past. It's true that humans also have culture but this doesn't meen that we can't test specific hypotheses after controling for culture. There are many studies that show universal mate preferences that fit specific hypotheses bases on sexual selection theory for example.

    SioFox, I can't really comment about this particula article that I havn't read. It might well be that it's complete and utter nonesense. But why is it that any time that someone conduct a bad study and mention the world evolution, people happily dismiss the whole field of ev psych? I assume that in any other scientific field every study is done perfectly and with no reservations.

  12. Reasoning/arguing is how we avoid Quine's "gavagai" problem. It is how we learn to coordinate our conceptualizations and meanings. The difficulties that feral children have, might be partly because they have not had much chance to engage in reasoning during their formative years.

    I would guess that arguing to reach mutual agreements and reduce conflict is far more common than arguing to win.

  13. Gil,

    I understand what you're saying. There's clearly a spectrum of scientific inquiry. Some questions lend themselves to scientific exploration more readily than others. I'm sure we can agree on that.

    Evolutionary psychology like sociology is inherently more difficult to study scientifically than physics or biochemistry. I think of it as largely pre-scientific in much the same way that psychology was for much of its existence. It's interesting. Many people are asking insightful questions and coming up with interesting answers/explanations. What we really lack is the methodology to make a lot of evopsych conjectures scientific hypotheses.

    I think that's what makes Massimo's point about there being no new data so salient. New hypotheses generally come about because new data don't fit the old hypothesis. In the case of this article I'm not even sure what the old data really is. That individuals reason poorly?

    You are quite right in stating that it would be unfair to single out any article and dismiss an entire discipline. That is, of course, unless each of these bad studies are representative of the discipline itself.

    I'm not an evolutionary biologist or a psychologist so maybe I've only been exposed to the bad studies (this article wasn't even a study). If you have some examples good evolutionary biology I'd be very glad to look them over. If the data are there, I'll certainly change my position re:evo psych.

  14. Massimo,

    I didn't mean to imply that you don't understand adaptationism, merely that you left it out of your discussion of evolutionary psychology in the podcast you cited. Indeed, you mention various methods of showing that something evolved (e.g. comparative evidence, ongoing selection) yet you conspicuously leave out what George C. Williams referred to as "evidence of special design." I find this especially odd, given that this principle is fundamental to much of evolutionary biology. Do you disagree with Williams that evidence of special design is a valid way of showing that something evolved? Or do you just think that this kind of evidence is usfeul for every animal except homo sapiens?

    One quick point. You write:

    "...in science the question is most decidedly not whether an explanation fits the evidence, because it is notoriously too easy to produce just so stories that fit. "

    Under this view, the theory of evolution is a "just so story," for Darwin used it to explain preexisting data.

  15. SloFox, I agree that ev psych is not physics or chemistry but it has to be at least at the same level as other psychological sub fields.

    You see, here the double standard. Why is ev psych inherently more difficult to study than social psycology? If we accept that theoretically we should take into account both evolution and culture, then any theory in the social sciences that doesn't rule out evolutionary forces is flawd.

    I am not sure what you mean by lack of methodology withing ev psych? if you read papers in the field you will dfind some of the most creative and rigorous scientific methods that you can find in any of the other social sciences. Good ev psych studies postulate hypotheses based on the available data or theory and go to test it, ideally cross-culturally. I don't see anything wrong with coming up with theories and hupotheses even without testing them immediately as in this article. This happendsall the time. Of course we need to find data that will either support or refute any hypothesis.

  16. With their ability to gain power without reason does that make republicans and reality TV stars the next stage of evolution?

  17. Gil, I briefly mentioned the major ways in which biologists test adaptive hypotheses, and at least one of them has to apply, otherwise one is into the realm of pure speculation. It just happens that all three are exceedingly difficult in the case of humans.

    Pin, Williams' argument is the same as Dennett, when he says that adaptation should be considered the null hypothesis. I don't buy it, partly because of my distrust of null hypotheses to begin with (again, see my Making Sense of Evolution, with J. Kaplan). Yes, apparent design certainly suggest selection, but the choice is never that simple. In this case, parts of the brain apparatus necessary for reasoning may well have evolved by selection, but in response to different pressures from those hypothesized by the authors. And some structures may have been co-opted at one time or another. So, it isn't a question of adaptation vs random stuff, it's a question of many possibilities for adaptation, and many more for constraints and exaptations.

  18. Gil,

    I think that social psychology and evolutionary psychology both rest on shaky ground. I agree with you that truly comprehensive psychological theories should take evolution into account. I just think that the evolutionary component is likely to remain somewhat nebulous.

    One of my fundamental objections to evolutionary psychology rests on the difficulty we have in defining cohesive cognitive traits. To cite a common example, "Is language a coherent cognitive function?" My answer is maybe. From a neurological POV language represents a collection cognitive capacities that are so intricately intertwined they, in many ways, represent a coherent system. Does selective pressure act on the components or the system as a whole? Probably both, but how do we figure this out?

    Certain genetic studies (e.g. FOXP) can help tease out an answer. Without an understanding of the environment in which these changes took place, however, we must still make a leap of faith regarding what we see now and the conditions under which a given trait/gene was selected. I don't think cross-cultural testing necessarily solves this problem. It may demonstrate the ubiquity with which a trait or function is present but it doesn't seem to add much regarding selective advantage.

    The bottom line for me is that the conclusions that are often drawn by evolutionary psychology (e.g. the article in question) require huge assumptions to be made. Assumptions are fine as long as they can be subsequently tested. I think our understanding of modern psychology is still too limited be making the assumptions. The limitations we have in studying human psychology make examining them through an evolutionary lens even more complicated.

    I think it's very interesting to speculate. I don't have a problem with that. I enjoy reading about evo psych hypotheses. I just think the science is still really weak. There's nothing "wrong" with coming up with hypotheses. For me evo psych hypotheses will probably remain on the low end of my belief asymptote for quite a bit longer--probably the rest of my lifetime--unless some revolutionary data comes along.

  19. Massimo,

    As regards the constitution of "reason," I wonder, for example, if we accept that the development of language or the capacity to speak and to signify objects is a major component of "reasoning," that claims for the evolutionary selection of language ability may also be a direct (?) selection for "reasoning" capacity.

    In other words, the linguistic capacities that evolution developed may not be capable of being separated from "reasoning" capacity. As humans engaged in more complex linguistic uses, I tend to believe that such events necessitated reasoning capabilities (that may be a blind assertion, but it seems sensable). And, from there, it seems appropriate that evolutionary forces that were molding humans to be greater users of language, were just as equally molding them to be users of "reason." That which made language capacity a trait to be selected cannot be separated from the reason "reason" was being selected.

    I agree that reason comes from various brain functions, but in the similar manner, linguistic capacity developed in coordinance with our visual capacities, our memory capabilities, etc. For some of these traits, the claims made for why they were developing may be that they were in direct correspondence with what they contribute to our more general capacity for reason. Some of it may add to "reason" coincidentally, but it is possible that some development, and I claim our "linguistic" capacity more often than not (especially later in our development), were being selected for because of there relations to reasoning capacity.

    That is probably just blind theorizing than empirically testable science, which is where I place most of evo. psych. anyways.


  20. After reading the article more thoroughly, I discovered that the authors' definition of "reasoning" is much more circumscribed than how Massimo or The New York times has characterized it. I agree that it is implausible that "reason" in its broadest sense cannot be said to have a single coherent function. However, what they are calling "reasoning" is not nearly this broad. For instance, they write:

    "What characterizes reasoning proper is indeed the awareness not just of a conclusion but of an argument that justifies accepting that conclusion."

    "The mental action of working out a convincing argument, the public action of verbally producing this argument so that others will be convinced by it, and the mental action of evaluating and accepting the conclusion of an argument produced by others correspond to what is commonly and traditionally meant by ‘reasoning’ (a term that can refer to either a mental or a verbal activity)."

    So it looks like they are just using "reasoning" as a synonym for "producing and evaluating arguments," in which case it is not all that far-fetched to claim that this faculty evolved for the purpose of winning disputes.

    Furthermore, they do not even go so far as to pin this as its main function. For instance, they write:

    "...we are not arguing against the view that our reasoning ability may have various advantageous effects, each of which may have contributed to its selection as an important capacity of the human mind. We do argue, however, that reasoning is best adapted for its role in argumentation, which should therefore be seen as its main function."

    So, all in all, it looks the authors actual position has been caricatured beyond recognition by journalists and philosophers eager to make them sound stupid. Clearly, people should have read the article more thoroughly before jumping in to hack down straw men.

  21. Correction: when I wrote "pin this as its main function" I meant "sole function."

  22. Lyndon,

    You are quite right that anything that might reasonably qualify as the capacity for "reason" is intricately intertwined with language--at least in humans. There are those that argue that without reason there can be no language and without language no reason. I am not one of those but will concede that the more abstract and conceptual aspects of reason likely require language. I think this can get particularly tricky when you start talking about AI (so I won't).

    Even if we say that language is necessary for reason it is probably not sufficient. I would argue that cognitive capacities such as memory, concept formation, problem solving/logic, etc. are also key components of "reason" and, in humans, also at least partially intertwined with language. There is evidence supporting the development of these and other components of reason in many mammalian species, independent of language. Whether or not you believe these animals have the capacity to reason it is very certain that pre-linguistic humans and their ancestors also had these capacities.

    Language very well may have been the icing on the cake allowing for better synthesis of these capacities and allowing them expand well beyond any other species. That doesn't answer the question of *why* it was selected for. It might be that language improved the ability to reason and therefore imparted a survival language. But it may not. Maybe language-enabled humans were able to woo their mates with poetry and non-language-enabled humans could not and the rest of reason was a serendipitous offshoot. This is obviously ridiculous but language offers many advantages independent of reason. If we could somehow impart language on other primates we might find ourselves in a Planet of the Apes situation. Language is definitely a game-changer but maybe or maybe not because its ability to hyperbolically augment our capacity for reason.

    There's also some wonderful literature about the importance of emotions in decision-making. This certainly factors into individual failures of reason as a mechanism for truth discovery and contributes to things such as confirmation bias and other irrational behaviors.

    I don't think there's a consensus among evo psychologists regarding language development let alone reason. Data might help sort out the theories a bit. Good luck to them in coming up with it.

  23. pin pin,

    The authors of this particular paper may have been unfairly caricatured as part of an overall smack-down of evolutionary psychology. Their paper was pretty thorough and I enjoyed their review of the "reasoning" literature. They cover a lot of ground and confirm the (well-established) conclusion that human beings are pretty bad at using reason to evaluate the truth content of arguments.

    They also demonstrate pretty convincingly that, on the whole, the way in which we produce and evaluate arguments can be useful in argumentation (at least with those who are just as bad at evaluating arguments for truth content).

    None of this, however, means that reasoning is a coherent trait that underwent evolutionary selective pressures. One of my big beefs is not the fact that they discount the other advantages that reason may have imparted to our species but the fact that they assume without providing any evidence that "reasoning" is a coherent function.

    Before we were able to argue with words we argued with sticks. From an evolutionary standpoint, arguing with words may have been more advantageous than arguing with sticks (digression: I'm not sure this is true. To paraphrase Woody Allen, when it comes to neo-Nazis baseball bats are more effective than satire). Once we were able to speak, our methodology for settling disagreements may have changed independent of any selective pressure.

    It is interesting (though admittedly absurd) to note that if the authors' arguments are truly flawed with regard to coming closer to the truth then their seemingly persuasive article is itself anecdotal evidence for their argument that "reasoning is best adapted for its role in argumentation." I think someone else made this observation earlier.

  24. pin,

    I doubt that your quotes can turn the authors' definition of reasoning into anything more amenable to evolutionary analysis, for the same exact reasons already expressed above.

    I would also like to underscore again that I'm not "just a philosopher," I am an evolutionary biologist with 25 years of experience in the field. I can recognize a just-so story when I hear one.

    Incidentally, if you really want to restrict the authors' objective to explaining formal logical reasoning, then I don't see how *any* explanation based on natural selection could possibly work, considering how very very recent (and how much of a cultural product) formal logical reasoning actually is.

  25. Massimo and SloFox,

    Thanks for the continued discussion. Of course, the evidence they provide doesn't prove that what they call "reasoning" (producing and evaluating arguments) evolved for the function they propose. I think, however, that it is suggestive, and hopefully will inspire more research on the topic. It should be noted that evo psych is very much enmeshed with the view that the mind works more or less like a computer, and evo psych analyses typically spring forth from this assumption. If this assumption is valid, then we are capable of reverse-engineering the computations the brain performs rather than their instantiated smattering of brain regions. The authors certainly tried to frame "reasoning" in computational terms, but perhaps they did not succeed in this endeavor. If they had provided a more rigorous model, and then provided copious evidence in support of this model, and then reverse-engineered the model with regard to its function in argumentation, would you have been more convinced? I certainly would have. I agree that it is difficult to test adaptive hypotheses, but it is far from impossible. Adaptationist reverse-engineering is the key, and whether or not you guys agree with this method, it has been tried in tested in evolutionary biology, and has paved the way for our detailed understanding of the human body (i.e. the heart is for pumping blood, the liver is for detoxifying, etc.). If something is improbably organized in a functional way (whether it be a stomach or a lung or a system of computations) then chances are it evolved to fulfill that function, for natural selection is the only process we know of (indeed, the only process in principle, as Dawkins would say) that can give rise to such functionally organized complexity. Grammatical language, I think, has passed the probability threshold for being considered an adaptation (for instance, see pinker's "language as an adaptation to the cognitive niche"). Certain emotions are getting there, pregnancy sickness has gotten there, certain sex differences are probably there, etc.

    At this point you are probably thinking that learned behaviors can account for some of this functionally organized complexity in humans. Perhaps expert chess players may show functionally organized computations for performing chess, and so this gives the lie to adaptationist analyses on humans.

    This line of argument is fallacious, as a trait like chess playing that takes years of conscious effort and precious brain energy to acquire violates Williams' principle efficiency. A true adaptation would develop spontaneously and consistently with minimal input. This is why evolutionary developmental psychology is so important in adding to the case that something is an adaptation. For instance, if confirmation bias could be shown to develop concurrently with reasoning skills in children, this would bolster sperber and mercier's case.

    Again, while adaptationist analyses are more difficult in humans because the learning alternative needs to be ruled out, they are far from impossible, as pinker's work illustrates. The two most common ways of ruling them out are through developmental studies and through cross-cultural research.

    One last pont: the authors were decidedly not trying to reverse-engineer formal logical reasoning, which is of course a modern phenomenon. They were trying to reverse engineer more basic intuitions -- present in all cultures -- of whether an argument sounds "right" or "wrong."


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