Evolutionary Psychology

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Robert Kurzban

The Evolutionary Psychology Blog

By Robert Kurzban

Robert Kurzban is an Associate Professor at the University of Pennsylvania and author of Why Everyone (Else) Is A Hypocrite. Follow him on Twitter: @rkurzban

Why You Should Stop Waiting For John Horgan to Master the Distinction Between “Ought” and “Is”

Published 29 May, 2012

In the October 1995 Issue of Scientific American, John Horgan published a piece on the previous summer’s annual meeting of the Human Behavior and Evolution Society (HBES), which had taken place at the University of California Santa Barbara, where I was, at the time, pursing my PhD with Leda Cosmides and John Tooby. (A photo of the pair with a Swiss Army knife graces the second page of the article. It’s actually a nice shot.)

Probably the most obviously incorrect aspect of the piece is the title, “The New Social Darwinists.” Social Darwinism is, of course, a political ideology, a set of ideas about values, or political oughts; HBES is, of course, a scientific society, and presenters at the conferences were making positive claims, about what is. Interestingly, in the body of the piece, Horgan explicitly acknowledges the is/ought barrier, writing of the attendees that “[m]ost shun the naturalistic fallacy, the conflation of what is with what should and must be.” His choice of title might, one could generously suppose, be intended as a play on words of some kind.

Still, a recent piece by Horgan suggests that he still hasn’t quite been able to keep “is” and “ought” distinct. In a blog post at Scientific American, Horgan criticized New York Times columnist David Brooks for looking to some of David Buss’s research in trying to explain the killing of 16 civilians by an American soldier. Horgan writes:

Evolutionary psychology, instead of giving Brooks fresh insights and leading him in unpredictable directions, seems merely to validate his dark, Hobbesian perspective on human affairs. Instead of blaming American war crimes on our killer genes or even “original sin” (yes, Brooks actually invoked that medieval superstition in his column), he should look more closely at political leaders, voters and pundits who have helped turn theU.S.into the world’s most warlike society. This is a cultural problem, not a genetic one.

The use of the word “blaming” carries what to me seems like strong normative connotations, as if the scientific explanation on offer somehow exculpates. In fact, Brooks was using Buss’s findings to try to explain not excuse the alleged massacre, writing that “the real question is not what makes people kill but what prevents them from doing so. People who murder often live in situations that weaken sympathy and restraint.” That is, Brooks was not, to my reading, blaming the alleged crimes on genes, but locating the explanation for them in the details of context. Now, the explanations on offer by Buss and Pinker, the latter of whom Brooks also cites, might be wrong. Indeed, Horgan seems to think that it was only recently that members of our species killed one another in large numbers. Whether or not there are adaptations designed for killing, it seems to me that people ought to be held accountable for murder either way.

A completely separate issue raised in the last sentence I quoted above is Horgan’s insistence on the archaic culture/genetic dichotomy, a confusion that, like his troubles with is and ought, he seems not to have been able to shake in the two decades he’s been trying to talk about evolutionary psychology. In the 1995 Sci Am piece, he mulls a hypothetical audience member listening to the late Dev Singh’s presentation on waist-to-hip ratio: “Surely one of Singh’s several hundred listeners—many of whom are female—will object that his research is offensive, silly or, at any rate, unscientific. Men’s tastes are obviously dictated by culture, someone will argue, rather than by ‘instinct’” (Aside: Singh’s “offensive, silly or unscientific” 1993 JPSP paper on waist to hip ratio has attracted 771 citations to date.)

Similar sorts of patterns are visible in Horgan’s thinking in his somewhat bizarre remarks about David Buss:

First of all, Buss is like a parody of an evolutionary biologist, who spins surveys of modern, mostly American college kids into cartoonishly simplistic proclamations about human evolution. As I noted in an October 1995 article in Scientific American, “The New Social Darwinist,” [sic] Buss’s speculations–which discount the role of nurture, culture and reason in shaping our behavior–are prime examples of what the biologist Stephen Jay Gould mocked as Darwinian “just-so stories.”

Holding aside the tiresome Gouldian trope at the end, his line about “mostly American” college kids is a bit ironic given Horgan’s remark in the 1995 piece (whose title he couldn’t quite render accurately) in which he specifically alludes to Buss’s worldwide research reach. Buss is, in any case, an odd target to choose, and label a “parody” of anything, given his stature and accomplishments, never mind his success in training students who have achieved, or are well on their way to achieving, prominence in the field.

Still, I do think there’s a larger issue here having to do with the is/ought barrier. It doesn’t seem to me that people perceive all “natural” explanations for social phenomena as excusing or justifying those phenomena.  After all, non-evolutionary explanations are also intended to be “natural” ones. But it doesn’t seem that social psychological explanations for, say, racial stereotyping – perhaps due to the tendency to use categories to simplify their world, or what have you – elicit the same sense that to have explained the phenomenon justifies or excuses it

To take a more controversial sort of example, consider the explanation for rape that it is due to male desire for power (as opposed to sex). The idea that men want power over women is a natural explanation, and therefore could, in principle, be perceived as justification for rape. In practice, it doesn’t seem to me that it ever is. My experience is that only certain sorts of explanations are viewed as having moral weight and, of course, it seems like explanations that refer to biological functions are frequently so viewed. If that’s true, there’s probably a natural explanation for that, too. But that doesn’t make it OK.

  • Carin Perilloux

    Great post!

    Perhaps the knee-jerk reaction we see toward EP explanations is not only whether the explanation is rooted in something ‘natural’, but (moreso?) how changeable that contingency is perceived to be by the audience in question (perceptions of naturalness and changeability may often be correlated, but not always).

    For example, when laypeople read about a evolutionary hypothesis stating that men have adaptations that lead them to rape women, this is often presented in popular press, or at least interpreted by popular press readers, as an “If male, then rape” type of contingency. Clearly if this is the perceived contingency, then this is not easily (possibly?) changed by any action we might choose to take to ameliorate the problem.

    On the other hand, let’s take the hypothesis that racism is the result of adaptations for categorizing aspects of our social world. My guess, and I may be wrong, is that people perceive this as more of a “If no other training [i.e., natural state], then people categorize by race” contingency, and therefore something that is changeable.

    • R J King

      I think you are right–we are dealing with folk biology here. The folk biology concept includes the “are we born with X”. Terms like “hard-wired” don’t help here–often they are used with a “its the biology stupid, you can’t change it” kind of flourish which critics then react to.

  • http://popsych.org/ Jesse Marczyk

    Horgan also seemed to have felt that violence in chimps communities was the result of human intervention as well. We transferred our violence memes to them, apparently (http://popsych.org/?p=121).

    That he thinks memetics provides a satisfying explanation says most of what one needs to know about his intellectual prowess in the area.

  • R J King

    I have been trying to spread the meme of “just-growed stories” as a riposte to Gould. Topsy, from Uncle Tom’s cabin when asked how she got there said “I s’pect I just growed”.

  • http://www.facebook.com/Jazitricks Jazi Zilber

    there is a deep cultural divide between facts searchers and world fixers.

    to the point. there is a bunch of causes for every phenomenon (a complex issue on its own) with levels of causation, multiple levels of analysis etc. [before we even start differentiating between actual and potential ;)]

    In an intuitive way, every packet of causation explained “steals” from other explanations. hence, saying that killing is caused partly by nature, seems to take away form the more morally motivating causes.

    Which is a central motive in many haters of evolutionary psychology.

    Ultimately, Horgan feels that giving naturalistic explanations has bad consequences. which is possible. but the questions is how much lying and hiding will we be asked for “for the good”

  • Jhorgan

    If you guys (author and commenters) represent ev psych today, the field is in even worse shape than I realized. You sound like evangelicals whining about a nasty anti-religion screed by Richard Dawkins. Look in the mirror, ask yourselves if your affection for adaptationist explanations of modern social behavior really stems from clear-headed analysis of data or from your emotional commitment to your scientific tribe. Try reading something that challenges instead of bolstering your bias, Sapolsky, Fry, Hrdy or de Waal. Because with supporters like you, ev psych doesn’t need enemies.

    • H Moss

      Hrdy was a keynote at the NorthEastern Evolutionary Psychology Society’s meeting last year. Just saying.

      • TypicalWiredReader

        If Horgan wants to fall under the rEvolution, that’s his choice…

    • JCrabb

      Perhaps rather than engaging in an ad hominem attack, you could address the points raised by Rob. You demonstrate repeatedly a shallow understanding of how genes and culture interact, as well as an apparent failure to understand the naturalistic fallacy. And given the folks you have declared proper alternatives to adaptationism, you apparently don’t understand the field of ev psych you are criticizing either.

      And your response to these charges is to blindly declare the field worse off for including individuals who point this out?

    • http://popsych.org/ Jesse Marczyk

      “I’m bad at understanding evolutionary psychology, therefore evolutionary psychology is in trouble” – John Horgan

    • http://www.facebook.com/kassorlae Eliyahu Kassorla

      I’m pretty sure important discoveries and what is known as “paradigm articulation” has a component of discussion about them – similar to Lavoisier’s discovery of oxygen helped bring chemistry along in rejection of phlogiston theory (eventually)… that did not make chemistry wrong. So, too, a lively discussion about details – of which there is broad agreement on the topic as a whole – is not “EP in a state of chaos” – it’s paradigm articulation

    • rkurzban

      John, let me express my thanks. First, thanks for taking the time to comment on my remarks here. Second, thanks for the reading list suggestion. I think you would find if you polled readers of this blog and the community you’re insulting that many if not most are indeed familiar with the authors you mention, even if they don’t always agree with them. I wouldn’t be at all surprised to find, for instance, that many in the Human Behavior and Evolution Society might be passing familiar with Hrdy’s work, a guess I feel comfortable with given that Hrdy is an officer of the Human Behavior and Evolution Society. As for the shape of the field, I have a different view, but it seems to me that posterity will be our judge.

    • http://www.facebook.com/Jazitricks Jazi Zilber

      John, calling David Buss “cartoon” is a sign of ignorance, and immediately makes me question your scientific ability to read.

      There are not many who do research in such a throughout, multi faceted etc. ways as as Buss.

      Anyone familiar with research who has read the works of David buss, has no choice but to stand jaw dropped and hope that there will be more researchers of this calibre.

      you will be much better of by not calling Buss names. One may even disagree with him. But respect to a high quality researcher is a natural obligation of anyone that knows what good research is.

    • Ian Weiss

      John, do you actually believe that David Buss or any other evolutionary psychologist wants to persuade people that nothing ought to be done to prevent cold-blooded murder? Do you actually think that the point they’re trying to make is “Look, humans evolved to commit murder sometimes, so get used to it?”

      (He probably won’t respond, but I think this is the type of question that proponents of Ev Psych need to ask critics like Horgan)

    • Thom


      These discussions are meant to be intellectual discourse. Your contribution is simply an ad hominem attack.

      You’ve written a piece. Rob has responded, making some critical comments about the substance of your argument. You’re not obliged to respond back, but if you do, you are obliged to address his points. You’re expected not to just insult the author, and those that agree.

      Not everybody who reads this will agree with Rob et al. But if they see that your only contribution is to throw insults around, you’re not going to persuade them that Rob is wrong. It’s in your interests to address what he has to say. So please, lets hear your response.

  • C_turchick

    I repost here what I posted in response to Horgan’s attack on Trivers…
    John, the self-deception you should be concerned with is your own wrong belief that you understand these topics well enough to have an opinion which you share with others. I have followed you around the internet correcting your views on the topic of human warfare over and over and over. So perhaps a series of questions…
    1)What group social territorial species does NOT engage in group level physical conflict with its conspecifics?
    2)If the Theory of Evolution is correct and the struggle for resources results in selection, how would a species arise where access to resources was largely determined at the group level, as with humans, but there was no conflict over resources at the group level?
    3)At least the following components of human behavior contribute to our waging war: desire to belong to a group, conformity, “patriotic” feelings of commitment to “our” group, stereotyping, tendency to dualistic thinking, automatic positive bias towards in-group, readily triggered negative bias towards out-group…why did these evolved predispositions not push our ancestors towards war when they work quite well to do so now?
    4)Why have you gone so far as to demand that others take an anti-scientific stance on this issue, changing their views because you do not like what you, in error, think the implications of their views are. Either they are right or they are wrong. How can you write for Scientific American and demand researcher bias? Is not making such a demand strong evidence that you are not engaging this issue in a scientific manner yourself?

    The fantasy that “we” are peaceful and “good” is what feeds into the fantasy that our conflict with “them” is caused by their being violent and evil. The fantasy you are fighting to preserve is an integral part of what allows us to justify going to war and killing people we do not know. Only by starting by admitting that all humans are predisposed to going to war can we begin to address war in an effective way that reduces its occurrence. Your efforts only hinder this progress. Please stop.

    I find it incredibly ironic that you would publish demands that others engage in researcher bias and now here you accuse others of being biased. So, bias is good as long as it is in the service of your delusion?

  • http://www.facebook.com/kassorlae Eliyahu Kassorla

    Rape is not about power in an evolutionary context – as explained by Tim Birkhead in his book about sperm competition, Promiscuity, is about reproductive cheating. Birkhead describes a spider that has a morphological appendage to pierce the females egg sack, depositing his sperm directly. Females of that species have developed both a harder keratin layer to prevent the force-choice, as well as a slight move of the egg-sack, preventing the “fist-come, first impregnated” manner of reproduction. In a context of female choice within sexual selection, there is a greater drive towards development of adaptations to deal with the great struggle. Birkhead also explains that in species with high inter-male competition, especially sperm competition – where females will mate with more than one male – that there is a positive correlation between the strength of sperm competition and the length of the female reproductive tract.


  • Jreed

    Naturally, there is some merit in the growing field of evolutionary psychology. However, it seems to get carried away with itself. For some reason, we are asked to swallow its conclusions without the same caliber of evidence that we expect of other sciences.

    Let us not confuse one kind of evidence with another: the psychological studies that show how the world “is” can be mighty impressive. My problem with evo psyche is that the leap between “is” and “how-it-got-to-be-this-way” is often unfounded.

    For example, the data on the Wason selection task is remarkably thorough. It seems countless variations on the Wason task have been performed, testing every alternative hypothesis to the “cheater detection” explanation. So what do we have? A mountain of fascinating data. What do some conclude? There is a module in the brain that evolved for the specific purpose of detecting cheaters. Hmm….

    PS: As long as we’re complaining about ad hominems, we should note the fallacy of appeal to popularity in this post. The number of citations the paper on waist to hip ratio has attracted does not make the conclusion more robust. It is evidence that people find these stories so compelling. They make sense. (They sometimes make way too much sense.) A compelling story is not science.

    • Alex

      I think your comment here on the cheater detection module may be a bit confused. Those who engage in evolutionary psychology use the tools of biology in order to generate falsifiable predictions and insight into how the mind works.

      The cheater detection module was not the conclusion, it was the starting point. If all evolutionary psychology did was look at data after the fact and craft a story to support those data it would be a very useless field–this may be what some people do, but no one who is really an evolutionary psychologist. Instead Tooby and Cosmides thought about the mind and what kind of systems a mind like ours should have. They then generated a hypothesis about a cheater detection module and tried their best to falsify that explanation. There hypothesis happened to be supported by the data and if it hadn’t been they would have revised their hypothesis–like all science.

      The goal of evolutionary psychology is to figure out how the mind works, not to figure out the exact historical circumstances that gave rise to our minds. This goal is in the first sentence of the Primer provided by Tooby and Cosmides ” The goal of research in evolutionary psychology is to discover and understand the design of the human mind.”

      Evolutionary psychologists are reverse engineers who use biology to constrain the types of functions that they posit. Ev psychers certainly use the information we have about the historical conditions of the EEA to constrain and generated hypotheses about the mind. However, the end game is to explain how the mind works–the evolutionary story only matters inso far as it helps them achieve that goal.

      • Jreed

        Alex, Thank you for your comment. You have painted a flattering portrait of EP: it’s reverse engineering that uses “the tools of biology in order to generate falsifiable predictions and insight into how the mind works”. However, it sounds to me like you have described neurobiology, not evolutionary psychology. (And again, I am not dismissing all of EP).

        So to revisit the cheater detection module: you’re not suggesting that Cosmides & Tooby started from something physical in the brain before they tested their hypothesis. You’re saying they “thought about the mind and what kind of systems a mind like ours should have.” From there they came up with the notion of a CDM and tried to falsify that. But that’s a strange strategy: solar system data might fit with Ptolemy’s epicycles, but that doesn’t mean the earth is at its center. An explanation can fit data perfectly–in fact, multiple explanations for the same data can co-exist– but as a realist, I’m looking for the one that’s right. I remain unconvinced.

        What I will concede is that we have to start somewhere, just as astronomers did. That, I think, is why you defend C&T, and why it sounds like I am attacking them. I’m not. I just don’t buy the CDM. I looked at the selection data for over a year, and if there had been a physical module I could have consulted, I might have believed we could bridge the two (the anatomical structure with the baffling and fascinating psychological data). Instead I am left with no reason to believe in the module, which you say prompted the investigation. (I guess we should be clear on what we mean by “the investigation,” because Wason’s selection task from 1966 was not devised with CDM in mind. It was all those variations on the theme later that were meant to directly confront the CDM question.)

        • Mike McCullough

          Hello, JReed and others–Looking for an identifiable anatomical structure to correspond to a discrete cognitive process may be asking too much of neuroscience at this point in time. Enough neurons are packed into a voxel (the unit of spatial resolution of an fMRI) to embody many thousands of discrete computational devices, and with a suitably compressed code, a single sensory neuron could transmit through its natural firing rate approximately 30 words of meaning per minute. You may not need that many neurons to get really powerful computation done. Thus, we probably shouldn’t lose too much sleep over whether or not we have the MNI coordinate for a given mechanism.

          • Jreed

            Mike, I had no real hopes of finding an identifiable anatomical structure. That was more a rhetorical point: that if there were such a structure, it would lend credence to the cheater detection module (in the “original, Fodorian” sense–meaning encapsulated). I would have guessed that in the real brain, not only can we *not find coordinates for most mechanisms (assuming they exist), but that they are distributed and capable of redundancy.

        • Alex

          I am not saying that their model is correct because it hasn’t been falsified yet, but merely noting that the fact that they used principles of natural selection to generate their hypotheses does not place a special burden of proof on them.
          Their hypotheses about the mind are just as falsifiable as the hypotheses generated other ways (such as consulting one’s intuitions). Like good scientists they made every effort to falsify their hypothesis, it just happened not to be falsified. The Ptolemaic model was eventually falsified and if C&T are wrong about cheater detection their explanation too will be falsified.

          You are using a very different meaning of the term module then evolutionary psychologists (the link below does a good job explaining this confusion, I think it’s an unfortunate word that is used to mean two very different things) By a module you seem to mean something like physical localization in the brain whereas evolutionary psychologists instead use the term module to mean a functionally specialized computational device. There is no reason a priori to think that because a system is specialized it should occur in only one brain region. Therefore, one can do a very good job understanding how the mind works by studying these computations and not knowing exactly where in the brain these things happen. One can also do a great job running experiments without knowing anything about natural selection. However, neuroscience and evolutionary psychology are important tools for answering questions about how the mind works.

          Link for EP’s usage of the term module:

          • Jreed

            Alex, I don’t think that “the fact that they used principles of natural selection to generate their hypotheses” places a “special burden of proof on them.” I merely argue that they should have the same burden of proof as any other science.

            Thank you for the paper on modularity. My concept—my definition—of modularity came from Fodor, it involved “fixed neural localization,” and in this paper Barrett & Kurzban refer to the “original” concept of modularity as “Fodorian.” Since it came from Fodor, this is not a case of “module” having a discipline-specific meaning in EP—it’s not quite fair to suggest that I naively misunderstand the word. It seems the word has evolved for the purposes of EP. I am perplexed as to why evo psychologists would continue to use the word “module” if it is so problematic. My knee-jerk response is: If we stipulate that “module” now means (B&K) “functional specialization, rather than Fodorian criteria such as automaticity and encapsulation,” are we not just redefining “module” to the point where it’s merely a metaphor? Where is the scientific triumph in having a robust metaphor? (Actually, I can argue with myself on that one.) But I have to finish the paper—maybe they answer this question. I am intrigued; it’s too bad I didn’t have this in 2003.

          • Alex

            I think they (EPs) do have the same burden of proof, they run experiments to verify or falsify their hypotheses. Again, they are making hypotheses about how the mind works, not about the exact historical circumstances that caused it to be so. Just like any cognitive science hypothesis, theirs is falsifiable.

            As for the module confusion,I admitted that you are not being naive, I think it would be better if Ev Psych eschewed the term “module” which leads to endless confusion. However, it has become so integrated with the field that I think it might be hard to remove this term.

            Thinking of mental systems as distinct functionally specialized devices that perform computations is extremely useful for discovering how the mind works and is much more than just a metaphor. The natural selection bit comes in when EPers think about candidate computations the brain should be designed to perform. One could just as easily use their intuitions to generate such a hypothesis, but adaptive analysis tends to generate more nuanced and correct hypotheses–or at least that is what people who practice EP believe to be true. That’s it, just an approach/tool for understanding how the mind works, no more, no less.

  • Helian

    Most of the commenters here are aware of the absurdity of accusations of genetic determinism, social darwinism, telling of just so stories, the double standard in demands for “evidence,” etc. However, I doubt that they are seriously intended to impress professional evolutionary psychologists. They are directed at a much larger and less sophisticated audience. They are manifestations, not of a difference of opinion regarding scientific truth, but of a battle between ideologies.

    Evolutionary psychology isn’t happening in a cultural and social vacuum. If ever a discipline demanded consilience, EP is it. The idea that it can be treated as an isolated specialty, as if it were some arcane branch of solid state physics or fluid mechanics, is fundamentally flawed. Many academics are trying to teach it that way, and they are doing their students a grave disservice. EP is relevant to, and, in many cases, contradicts cherished ideologies and worldviews. For example, an understanding of the history of socialism and the contradiction between the sort of human beings it required and human beings as they actually are is at least as important to a thorough understanding of the field of EP today as expertise in kin selection or the sex life of bonobos. Without that understanding, evolutionary psychologists will never understand the ultimate cause of the objections of the Horgans of the world, and will never get off the treadmill of answering them in detail, over and over again. After all, most of the same objections were made in Lewontin’s “Not in our Genes,” published in 1984, and, for that matter, in Ashley Montagu’s “Man and Aggression,” published in 1968. The reasons for such objections have never had any thing to do with science. They are to be found in the ideology of the people who make them.

  • Emp123

    Speaking of the is/ought gap, lately I’ve been thinking about the Shakers. The Shakers practiced celibacy and, surprise, surprise, they went extinct. So someone might say you can’t infer from “if your group practices celibacy they will go extinct” to “you ought not practice celibacy.” Fair enough. But the result is the same, a world without the celibate group. It seems to me that the way is not to bridge the is/ought gap but just go around it. Values have survival value. You can’t rationally argue with the Shakers, or other self-destructive groups, in the sense of laying out a valid written argument where the conclusion of “ought” follows deductively from the “is” premises, but you can urge groups that want to stick around (wanting to stick around is itself a advantageous value) to do what will allow them to stick around. And so a new field of normative ethics (one that I think might eventually be the entirety) would be the study of adaptive/advantageous/enduring values that those who wish to stick around would be advised to adopt. It doesn’t replace the is/ought issue, it just renders it uninteresting the way that the Shakers’ values, while interesting in an historical sense, are uninteresting when looked at from this view. Someone who wants to claim that your survivable values aren’t absolute is free to go their own way and adopt poorly survivable values, but their values are doomed to die out. (Of course this renders the possibility that there might be conflicting values that have equal survival value.)

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