Arthur Jensen and J. Philippe Rushton's 2005 paper "Thirty Years of Research on Race Differences in Cognitive Abilities" is a beautiful work for both its rigor and scientific reasoning. The two scientists look at ten separate kinds of evidence that could possibly bring to light the causes of the black/white IQ gap. They are "the worldwide distribution of test scores, g factor of mental ability, heritability, brain size and cognitive ability, transracial adoption, racial admixture, regression, related life-history traits, human origins research, and hypothesized environmental variables." Rushton and Jensen find that every area points to an at least partly genetic explanation.
We could imagine a world where whites were smarter than blacks in only 60 or 70 percent of the countries studied instead of all. Or where the racial differences in IQ scores were the same everywhere except in cases of cross adoption studies. Or a world where there were IQ differences even when blacks and whites were adopted into similar environments but there were no correlations between skin color and IQ amongst blacks. That's not our world. The question on whether there are inherent racial differences in intelligence is like a math problem where the calculator, your own work by hand, your friend, and the back of the book are all independently giving you the same answer.
While Jensen and Rushton's "Thirty Years of Research" is an example of how to reason, The Genius in All of Us: Why Everything You've Been Told About Genetics, Talent and IQ Is Wrong by journalist David Shenk is the polar opposite. I've written many book reviews, which usually consist of me summarizing the work and giving my thoughts on a few ideas. It would be impossible to do so here. While Rushton and Jensen provide a falsifiable theory that makes predictions, and they examine it from several perspectives, Shenk presents a collage of pieces of data only tenuously linked to one another. He provides no clear ideas that could be directly challenged. If I was to sum up Genius, then I'd say it's about how everybody has the potential to be a, well, genius.1 The view that genes directly make us who we are is said to be simplistic; how they interact with the world is so unpredictable that we really don't know how anybody will turn out. Instead of Genes + Environment, the new paradigm is GxE.
Telling people what they want to hear is big business. Richard Nisbett was featuredtwice in the New York Times last year for his book arguing for an environmental cause for the black/white IQ gap. Rushton and Jensen showed that Nisbett's evidence was cherry picked to back up the egalitarian hypothesis. Genius has created a similar buzz. Excerpts from the book can be found at The Atlantic and The Wall Street Journal.
Lists are sometimes indicative of a lack of creativity on the part of the writer, but the logical errors in Genius make my including a long one impossible to resist. Consider this as instructional piece on how not to reason. Here is just a sample of Shenk's mistakes.
Cherry-picking the data
Shenk cites a 2003 study by University of Virginia psychologist Eric Turkheimer purportedly showing that intelligence is less heritable in lower socio-economic status (SES) groups. This article was a favorite of Nisbett, too, though Jensen and Rushton pointed out at the time that
The Turkheimer et al.  study that Nisbett cites is an outlier. In Britain, the exact opposite of Turkheimer's result was found in over 2,000 pairs of 4-year-old twins (N = 4,446 children), with greater heritability observed in high-risk environments . A re-analysis of the Hawaii Family Study of Cognition also found contrary results to Turkeimer's. Nagoshi and Johnson  found no reduction in the relationship between parental cognitive ability and offspring performance in families of lower as opposed to upper levels of socioeconomic status. In the 1,349 families they studied, the relationship remained the same across tests, ethnicity, and sex of offspring.
Expect the Turkheimer study to keep appearing in books of the egalitarianist genre. (Though I must point out that while Nisbett's Intelligence and How to Get It had some decent internal reasoning and accepted many hereditarian claims having nothing to do with race, neither can be said of Genius.)
Lying by Omission
Shenk: "the very belief of possessing inferior genes is perhaps our greatest obstacle to success." Really? So in that case, the more self-confident kids should have the highest grades. They don't.
Assuming correlation implies causation
In trying to argue against The Nurture Assumption by Judith Harris, Shenk claims that parents actually do matter by pointing to studies showing that low SES caregivers who are involved with their children have better results with them. The simplest explanation is that parents who take better care of their offspring are genetically more competent and they pass these traits on to their relatively well-adjusted kids. While I'm used to journalists making the correlation/causation mistake when ignoring hereditarian arguments, this is the first instance I've seen the error in a work where an author is pretending to argue directly against them.
It's actually worse than that, as Shenk picks and chooses which evidence he wants to bring forward based on whatever he needs to prove the particular point he wants to make. So most of the time he claims that the general public interprets cross-adoption studies wrongly, until he can find the one he likes. Sometimes they're ignored, as when he brings to light evidence that children of professionals hear more words growing up and acts as if this proves the importance of environment. Only that Shenk doesn't argue for the primacy of nurture, because he uses the tool of...
Obstruction or "Throwing up Smoke"
If you don't like the results, pretend like the question is meaningless. Since nature has won, we're now told that the phrase "nature/nurture" "makes no sense today." Once again, that is until you find one of the few studies that lean towards nurture.
The chapter on racial differences never lets the reader know that there is an IQ gap between the races. Instead, the author points to black domination of running and tries to prove it's based on culture. He thus indirectly argues against a genetic basis for the black/white achievement gap, without offending the delicate sensibilities of his readership.
Shenk pulls out Lewontin's Fallacy, claiming that there is more genetic variation within each race than between races. While this is true when comparing isolated loci between individuals, a geneticist looking at a few more can classify people with 100 percent accuracy.
Ignoring the Law of Diminishing Returns
Since we've seen gains in IQ over the last 100 years (Flynn effect) there's no such thing as innate intelligence. I suppose that gains in height mean that we'll all eventually be ten feet tall.
Pretending to Concede an Argument and then Ignoring It
I counted at least eight instances of the author saying some variation of "Of course genes matter, but..." and then going on to act as if for all practical purposes genes don't matter.
A social science book would be boring without any anecdotes at all. The problem comes from making them central to your argument instead of peripheral to it. Michael Jordan trained harder than anybody else, we know. But how do you explain the success of Allen "We talkin' bout practice?" Iverson?
Did you know that no race has "an exclusive lock on a particular body type or secret high-performance gene"? I read Professor X who told me that Mongoloids had the conformist gene, Negroes had the running gene, and Nordics the multi-cultural gene. Thankfully David Shenk has set me straight. Incredibly, the author feels the need to tell us that "complex traits like physical coordination, personality, and verbal intelligence" are not inherited in a Mendelian fashion. Whom does he think he's refuting?
And lest the reader think I'm being unfair by picking out a small part of Shenk's argument as my "strawman," know that as far as I can tell unpredictability at the individual level and the obvious fact that complex traits are controlled by an interaction of genes (xE) is all that he means by "GxE, not G+E." Elsewhere, a trio of journalists are quoted as telling us that "Identical genes don't produce identical people."
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I could go on for a very long time, but that's more than enough. Often egalitarians have a method they use to convince the reader they're the intellectual winners by telling us straight out that the issue is settled. One of many examples from this book (which also manages to include the fallacies "Obstruction" and "Burning Strawmen") is as follows: "The catchy phrase 'nature/nurture' sounded good a century ago, but it makes no sense today, since there are no truly separate effects."
Shenk doesn't use the more sophisticated nurturist tactic of trying to sound convincing by putting the adjective they want to use to describe what they don't like in the subject instead of the predicate. For example, instead of saying "The Bell Curve was a pseudo-scientific work and did much damage" an author will write "The psuedo-scientific Bell Curve did much damage," as if the epithet is an afterthought and not the main point. It seems that this tactic is only used to describe inherent population differences, however, and rarely for hereditarianism in general. Perhaps this is because liberals know they can't casually go around calling everything "discredited." People may start to wonder why they spend so much time on things that nobody important takes seriously. Thus they use the adjective switch for only what truly frightens them, the knowledge that can lead to the end of their egalitarianist scheming and to white liberation from guilt, self-hatred and the acceptance of the multi-culturalist state: the findings of race science.
Nobody ever thought that one gene controlled intelligence or self-control or that an inherited trait exists independently of its environment. Refuting these non-arguments does not by any stretch of the imagination mean that it's meaningless to talk about the relative importance of nature and nurture. Twin studies showing that genes are more important than all environmental factors combined are brushed aside because the heritability estimates "pertain only to groups-not to individuals." (and then you're supposed to forget that he said this a little later when he cites the Turkheimer study) But I thought the title of this book was "The Genius in All of Us," not "The Genius that Might Exist in Some of Us and Prove to be the Exception to the Rule." Is this supposed to be a science or self-help book? Neither, it's a political one.
Even if it is the issue that dare not speak its name throughout the book, Genius is about more than just race. It's a complete denial of reality, a hope for a world that cannot be and a sign of desperation in the ranks of the genetic deniers. For it's only with topics that they care deeply about that smart people can look at the evidence and come up with something as poorly reasoned as The Genius in All of Us.
1 -- This seems to be the message except the few times when he says that not anybody can do anything. Maybe he means that everybody has at least one area they can become a "genius" in, though it's really hard to tell. If Shenk was asked to describe his own book in two sentences, at least one of them would be contradicted by something else he says in it.