Making Sense with Sam Harris - #73 — Forbidden Knowledge

Episode Date: April 23, 2017

Sam Harris speaks with Charles Murray about the controversy over his book "The Bell Curve," the validity and significance of IQ as a measure of intelligence, the problem of social stratification, the rise of Trump, universal basic income, and other topics. If the Making Sense podcast logo in your player is BLACK, you can SUBSCRIBE to gain access to all full-length episodes at samharris.org/subscribe.  

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Okay, strap in. Charles Murray is a political scientist and an author. He is most famous for having co-authored the book The Bell Curve, along with the late Richard Bernstein. Now, to say that this book was controversial is really beyond an understatement. It is probably fair to say this is the most controversial book in the last 50 years. Now, the book looks at the growing role that intelligence plays in modern societies, and the authors worry about a kind of cognitive partitioning of our society into separate classes. There was a time when being a few standard deviations above the mean in intelligence

didn't get you very much when you're just plowing the field alongside your neighbors. But now you can start a software company or a hedge fund. And this leads to astonishing levels of wealth inequality and cultural isolation. This is a theme that Murray has returned to in his other work, and in a more recent book, Coming Apart, which we also discuss. Now, unfortunately for Murray, what we have here is a set of nested taboos. Human intelligence itself is a taboo topic. People don't want to hear that intelligence is a real thing and that some people have more of it than others. They don't want to hear that IQ tests really measure it. They don't want to hear that differences in IQ matter because they're

highly predictive of differential success in life, and not just for things like educational attainment and wealth, but for things like out-of-wedlock birth and mortality. People don't want to hear that a person's intelligence is in large measure due to his or her genes, and that there seems to be very little we can do environmentally to increase a person's intelligence, even in childhood. It's not that the environment doesn't matter, but genes appear to be 50 to 80% of the story. People don't want to hear this. And they certainly don't want to hear

that average IQ differs across races and ethnic groups. Now, for better or worse, these are all facts. In fact, there is almost nothing in psychological science for which there is more evidence than these claims. About IQ, about the validity of testing for it, about its importance in the real world, about its heritability,

and about its differential expression in different populations. and about his differential expression in different populations. Again, this is what a dispassionate look at decades of research suggests. Unfortunately, the controversy over the bell curve did not result from legitimate good-faith criticisms of its major claims. Rather, it was the product of a politically correct moral panic that totally engulfed Murray's career and has yet to release him. His co-author, Richard Herrnstein, died just before the book was published. So Murray weathered the storm alone.

And it rages to this day. The book was published over 20 years ago. And yet just last month, Murray was shouted down by a mob at Middlebury College, a mob that actually turned violent and sent the faculty member who was chaperoning him to the hospital. And it's that most recent attack, which is part of an anti-free speech hysteria that is spreading on college campuses, that caused me to finally pay attention. I should say that some researchers just performed a rather delightful experiment, which I just wrote about in the New

York Times. They took the text of Murray's speech, the speech he attempted to give at Middlebury, and sent it to 70 or so professors to have them rate it for political content on a scale of one to nine, liberal to conservative, with five being precisely in the middle. And the professors weren't told who the speaker was. And it got a rating of 5.05. Okay, right down the middle. When they sent it to another group of professors, telling them the speaker was Murray, the rating shifted a little, but not by much. The rating shifted a little, but not by much. The speech was now rated 5.77, just right of center.

The man is not Heinrich Himmler. But because I had assumed, as many of you probably have, who heard about the bell curve controversy, that when seemingly respectable people are calling someone a Nazi, and a fascist, and a white suprem supremacist and a eugenicist, well, then there must be something wrong with him, right? He must be getting what he deserves on some level. But what I found when I began reading Murray's work was a deeply rational and careful scholar who was quite obviously motivated by an ethical concern about inequality in our society. This is not a person who was in favor of discrimination.

Whatever the difference in average IQ is across groups, you know nothing about a person's intelligence on the basis of his or her skin color. That is just a fact. There is much more variance among individuals in any racial group than there is between groups. So besides being unethical and politically imprudent, it is totally irrational to treat people as anything other than individuals.

Murray and Herrnstein were absolutely clear about this in The Bell Curve. So what happened to Murray, as far as I can tell, has had nothing to do with errors of scholarship, of which undoubtedly there must be some, or for the way he's conducted himself since, or for his personal motives for discussing these topics in the first place. Rather, his scapegoating has been entirely the result of his having merely discussed differences in human intelligence at all. Now, it's certainly true that the definitions of both intelligence and race are open for debate, to some degree. And there can be cultural influences in the concepts we use that we

don't totally understand. But the efforts to invalidate the very notions of general intelligence and race have been wholly unconvincing from a psychometric and biological point of view, and are obviously motivated by a political discomfort in talking about these things. And I understand and share that discomfort, but any fair reading of Murray would acknowledge that he understands and shares it too. And one rarely encounters a fair reading of Murray. Whenever you see discussions of the bell curve, you can be sure that their authors felt themselves under immense pressure to dismiss it. And they wind up ignoring much of what Murray and Herrnstein actually wrote.

Then they argue in very sloppy ways against the concept of general intelligence. And this sloppiness still has the effect of being defamatory. I'll give you a sense of how insidious these attacks upon a person's reputation become. There are all the consequences that Murray knows about, obviously. The death threats, the hecklers, the disinvitations from speaking events. But then there are the things he can never know about. For instance, a couple of years ago, I was invited to write an essay for an academic journal. And I saw that one of the other contributors was Charles Murray. And at that

point, I hadn't read his work. And I only knew about him, or thought I knew about him, by reputation. And my first thought was, why do I need to be in a journal alongside Charles Murray? I just had Ben Affleck call me a racist on television for my criticism of Islam I was dealing with that blowback and the last thing I needed, I thought was to be publicly associated with Charles Murray now Murray can have no idea how many times people have shunned him in that way

nor do I have any idea how much that's happened to me for the lies that have been spread about my work. Now, I'm sure there are many things that Murray and I disagree about that we did not explore in this podcast. He's far more convinced about the social benefits of religion than I am, for instance. But I had another agenda. At one point, I think I likened our conversation to visiting a nuclear power plant after an accident to assess the damage. And it did feel like this. Honestly, it felt like the intellectual equivalent of going into Fukushima with a Geiger counter to see just how hot things are. Not something I was ever planning to do. And I do remain skeptical about the wisdom of looking for cross-cultural

or interracial differences in things like intelligence. I'm not sure what it gets you, apart from a lot of pain. So many of the topics I discussed in the podcast with Murray are not topics I would ordinarily think about or recommend that you think about. But the purpose of the podcast was to set the record straight, because I find the dishonesty and hypocrisy and moral cowardice of Murray's critics shocking. And the fact that I was taken in by this defamation of him and effectively became part of a silent mob that was just watching what amounted to a modern witch burning, that was intolerable to me.

So it is with real pleasure and some trepidation that I bring you a very controversial conversation on points about which there is virtually no scientific controversy. And it's with a man who could not have been a more genial and well-spoken guest. Meet Charles Murray. I am here with Charles Murray. Charles, thanks for coming on the podcast. It's my pleasure. So I first heard of you, as many people did, when you published your book, The Bell Curve, in 1994,

I believe. And this is along with your co-author, Richard Herrnstein. And this was without question one of the most controversial books in living memory. It focused on IQ and the differences in mean IQ between groups of people. And it was just treated like, let's say, radioactive communication. And like most people who first heard of you at that point, I didn't actually read the book. And I just assumed that where there was smoke, certainly that much smoke, there had to be at least some fire. And I just assumed that you had said something in those pages that was so intellectually or morally indefensible that that explained the backlash against you. And this is a backlash that continues to this day, and we'll talk about that. But I've since, in the intervening years, ventured into my own controversial areas as a speaker and writer and experienced many hysterical attacks against me

and my work. And so I started thinking about your case a little, again, without ever having read you. And I began to suspect that you were one of the canaries in the coal mine that I never recognized as such. And seeing your recent treatment at Middlebury, which many of our listeners will have heard about, where you were prevented from speaking and your host was physically attacked. I now believe that you are perhaps the intellectual who was treated most unfairly in my lifetime. And it's just an amazing thing to be so slow to realize that. And at first, I'd just like to apologize to you for having been so lazy and having been taken in to the degree that I was by the rumors and lies that have surrounded your work for the last 20 years. And so I just want to thank you doubly for coming on the podcast

to talk about these things. Well, that's very kind of you to say, but I'm curious, have you looked at the bell curve? Yes, yes. So now I'm deep into your work. So I know what you wrote there, and I know what I think about it, and I'm eager to talk about it. Me too. There's an aphorism from Nietzsche that I think will apply to this conversation, or at least I fear it will apply. And it's something like, when you force someone to change his opinion about you, he holds the effort this requires very much against you. And I think many of our listeners will be ill-disposed to change their opinion about you and your work. But I'm determined to

ram past that resistance insofar as that's possible. Well, could I just make a request of your listeners who really do resist that? I don't ask you to read the whole book, The Bell Curve, but it's not that much money on Kindle. And there's got to be somewhere on the internet, there's got to be chunks of the text. Just read a few pages of the thing. This is not a hysterical, this is not an Ann Coulter book.

It's not a Milo book. It's, of all the charges about the book that drive me nuts the most, I think perhaps it was Stephen Jay Gould, who probably a lot of your listeners are too young to remember, but who wrote the review of it in The New Yorker. And Gould himself was the author of a book called the mismeasure of man which many people see as the canonical refutation of uh of iq as being an important concept but anyway in the review gould was referring to the regression equations well as it happened with the division of work i did all the regression analyses and i was reading the review and gould made a little parenthetical remark,

I bet they only did them once. And I threw the book against the wall. I literally, my wife was in the room and I took it and I just threw it. Because thinking of the hundreds of hours that I spent on that. And not only that, when we had all of the analyses done, I'm afraid, Sam, a lot of this podcast is going to sound very self-referential and pompous. I don't know how to get around it. But this is the truth. When we got done with all of those analyses, I went back and I recreated them from scratch. I mean, recreating the variables again, doing the whole thing, and so that I could just get rid of any dangers of, uh, of a screw up. I had to make the identical screw up twice. In other words, there's still be a mistake.

Anyway, the, but the book, I would argue, all you need to do is read in it for a while and you will realize that things you have heard about it are simply wrong. Yeah. Well, I want to get to the most controversial points you make in the book and what you actually say about it are simply wrong. Yeah, well, I want to get to the most controversial points you make in the book and what you actually say about them and what kind of public policy recommendations you make on their basis, because it is the opposite of a white supremacist, neo-Nazi book, and you have been called both of those things. So let's get into it. What was your basic thesis in the bell curve? The thesis of the bell curve actually is very similar to the thesis of coming apart, which hardly anybody noticed. And that is, at the time we did it, we were saying we are looking at

a future which is being shaped by the radically increased value of IQ in the marketplace over the last century, and has also been affected by the increasing effectiveness of the higher educational system in getting intellectual talent wherever it resides and pulling it into elite universities. And the combination of these two things is creating a cognitive elite that is increasingly powerful, increasingly affluent, has its own culture, and is increasingly isolated from and ignorant of the rest of society. That essentially was the, well, that's a thesis of that book. That's the reason the subtitle is Intelligence and Class Structure in American Life. subtitle is intelligence and class structure in american life and as i said coming apart the first few chapters have large chunks of the bell curve um imported into it because in coming apart i was essentially saying it's no longer something that we're in danger of it's something that has happened

so that was that was the thesis and we spend uh the first eight chapters, well, no, first we spend three or four chapters talking about the nature of the cognitive elite and how it came about. Then we take eight chapters and we have the relationship of IQ to a variety of social outcomes, unemployment, poverty, educational attainment, crime, the relative roles of IQ and the basic socioeconomic variables in explaining the dependent variable. And for doing that, Dick, Herrnstein, and I restricted ourselves to a sample of non-Latino whites. And the reason we did that was we said, we know that the whole issue of IQ and race is very heated, and we're going to simplify things. We are saying this relationship of IQ to important social and economic outcomes exists in a population of non-Latino whites. And then after that, we can go to the issue of, well, does it apply to the nation as a whole? And that's the point at which we got into race. Right. So the most controversial area of the book is in your discussion around the mean difference

across races in population IQ. Right. It's important to point out here that even the topic of IQ, the topic of intelligence, is taboo. And people get uncomfortable in hearing that intelligence is something that even differs among people. Then when you add the fact that this difference is heritable and that it matters over the course of a person's life, that already is something that makes people very uncomfortable. Already, you seem to be opening the door to eugenics and other scary ethical and political ways of thinking. And then when you add to that the fact that there are detectable differences in mean IQ between races, then just everything goes completely haywire for people.

So I want to move through these concepts and claims somewhat systematically. But I guess before we do that, is there anything that has happened in the intervening years, either in your own research or in the research generally, that has changed the picture significantly from when you wrote The Bell Curve. Have any of your important claims changed? There have been many of our claims have had a lot of additional stuff. For example, take something like G, the general factor of intelligence. Right, which is what IQ tests measure.

Exactly. And this is something which, going back to Stephen Jay Gould again, he said, no, it all depends on how you do the factor analysis. You can either make G appear in your analysis or it could go away. It's a statistical artifact. Well, even at the time we wrote, in 1994, an awful lot of the things that Steve Gould claimed back in 1980, 81, I mean, they were just, no psychometricians took them seriously.

The work that had been done on it was very solid. The reality of G was already understood. But since then, it turns out that there are a whole variety of aspects of brain functioning, the quantity of gray matter versus white matter, all sorts of things which they're linked specifically to G, not just IQ scores in general, but they are most tightly linked to this general factor for intelligence. So if you had to say one thing that has had just an awful lot of additional verification and elaboration.

It's the reality of G. And, of course, Sam, we are also within a matter of years, I don't think that many years, before we will understand the functioning of intelligence down at the level of alleles and single nucleotide polymorphisms. We are already making a lot of progress on that. As of, to give you an idea of how fast the progress is, in 2013, I was doing a paper and so I set out to see, are there any SNPs, single nucleotide polymorphisms? They're the

sites in the genome that can take more than one form, and they account for all of human variation. I said, well, have the geneticists found any of these that have a direct relationship to social behavior or mental functioning or whatever? And I came up with, I think, seven or eight. And I looked again a year and a half ago, and it was in the low dozens, and now it's in the hundreds. And in a few years, it's going to be in the thousands. And so we will understand IQ, general intelligence, genetically. I think most of the picture will have been filled in by 2025.

There'll still be blanks, but we'll know basically what's going on. And just to finish up the other, was there anything that I changed my mind on after the bell curve came out? And the answer is no. There's been some interesting tidbits that I've been fascinated by, but the science in the bell curve was extremely conservative. I don't mean that politically. Dick and I, I mean, we weren't stupid. We knew that we were dealing with a complicated and controversial topic. And so we stuck very close to the scientific mainstream so that after the book caused such a furor, and this is easy enough for your listeners to Google for themselves,

they can just Google knowns and unknowns IQ and it'll pop up. The American Psychological Association established a task force in the year after the bell curve. And the task force consisted of 11 of the most eminent experts in cognitive functioning in the country, including people of various ideological perspectives. Because believe me, well, if you've been in academia, you know there's as much ideology within each discipline

as there is in politics. But anyway, the task force came up with a set of knowns and unknowns, and it tracked just about perfectly with the statements in the bell curve. So it wasn't the Dick and I were brilliant. It's the Dick and I were very, very cautious. So no, nothing has been overturned since the bell curve came out. And there's been nothing overturned in the area of racial difference in mean IQ. Oh, before I answer that question, I just thought of the sweetest vindication, uh, of the bell curve. So I better mention that there was a whole cottage industry of books in the year after the bell curve came out attacking the book.

This is the pseudoscience. And these guys don't know what they're doing. and then pointed out that in many cases, the role of IQ was far greater than the role of socioeconomic status, that Dick and I had not simply, we hadn't put enough independent variables into the equation. So we had occupation, we had income, and we had educational attainment, which to tell you the truth are basically the three components that social sciences had been satisfied with in measuring socioeconomic status until the bell curve came along. But we hadn't put in enough. So they were throwing in everything but the kitchen sink, a lot of which were things that

were very closely related to parental IQ. So a lot of the criticisms of the bell curve said, oh, if we add, let's say, the number of books in the house, then you can cut down a little bit on the role of IQ. Well, now, what do you suppose the relationship of number of books in the house is to parental IQ? Yeah. And so on and so forth. sweet vindication was when Christopher Winship at Harvard, and I'm blocking on the other guy's name. I'm sorry. Anyway, they did an analysis that Dick and I should have thought of,

because our major database was the National Longitudinal Survey of Youth. And this is on me, by the way, because I was taking the lead on the quantitative analyses, I knew that there were siblings in the NLSY database, but it didn't cross my mind to do fixed effects analysis, where in effect, you were analyzing the outcomes for siblings. And if you do that, you can control for everything in the shared home environment, just about everything. So you can do much more than add in one or two more independent variables. It's a really elegant control. And the, um, analysis was done and the authors were not happy about it, but, but listen, I don't want to, I don't want to, uh to diss them because they were honest. And they did point

out that, in fact, that when you use the sibling analysis, that the independent rule of IQ that Dick and I claimed was not attenuated more than fractionally. And in fact, they said explicitly they were surprised that it had not been. And in effect, all of our analyses about the effect, independent effect of IQ on social outcomes had a very powerful vindication. So I had to get that in. All right, now you asked about racial differences. Well, Dick and I considered the possibility of just leaving race out. And we decided that it was just the elephant in the corner and we couldn't do it. But we also could not talk about the national implications of our analysis of whites only unless we grappled with the questions, does an IQ test or an SAT test or any of these others,

does it measure the same thing in blacks as it does in whites? Is it as predictably valid? Is it contaminated by cultural bias? Is it contaminated by lack of motivation or a stereotype threat as something that came up after the bell curve, but now people would say stereotype threat doesn't work? We had to deal with that. We had to present the story of IQ tests as applied to African Americans and other minorities, and make the case that actually the tests measure the same thing in various populations. So we set out to do so. And we tried to work into the topic sequentially. The first simplest thing being are the test scores different for whatever reasons? And the answers for that are yes. They are for blacks and whites, there's about as a standard deviation as the usual

size of the difference. I'm assuming by by the way, that an awful lot of your listeners are statistically literate and they know roughly what I mean by a lot of these terms. But just to put it in more traditional terms, if you are one standard deviation below the mean, that means you're at the 16th percentile. If you're one standard deviation above the mean, that means you're at the 16th percentile. If you're one standard deviation above the mean, you're at the 84th percentile. That'll give you a sense of what a standard deviation is. IQ is normed so that the average in the whole population is always 100 or as close to 100 as possible. Although we'll get into this. IQs have been, those scores have been creeping up decade by decade for reasons that are not totally understood. So what you're

talking about is if the average... And the standard deviation of 15. So what we're talking about, if the average for white America was 100 at the time you wrote that book, the average for black America was 85 IQ. Right. Now, obviously, different tests give different results. And as time goes on this afternoon, we can get into, has the gap been converging, and then things like that. But one standard deviation for a considerable period of time has been a good benchmark for the size of it. By the way, there is also a difference between whites and East Asians. It's harder to pin that one down for a variety of technical reasons. Among others, until recently, we didn't have really good representative samples of Chinese living in mainland China, but it's probably three or four points.

And that's kind of a soft number, but clearer statement about differences with whites and East Asians is that East Asians have elevated visual spatial IQ. And with Latinos, which of course is not a racial group, it's an ethnic group, that's all over the lot. But there you're looking at that on the order of the low 90s as a mean for those in the United States. So first, we do simply the numbers on the differences exist. I think I should clarify a few things. So the disparity with East Asians is in the favor of the East Asians now, so they're higher in visual-spatial reasoning. So I feel like I should give a little context here just on the general concept of IQ and what it purports to measure, general intelligence. There is just this fact, which is now among the most well-attested

facts in psychology, that a person's ability to reason logically and mathematically and visual spatially, and along with their semantic knowledge of the world or the size of their vocabularies, for instance, all of these abilities are highly correlated. So it's this correlation that has been dubbed general intelligence, or G. And this is what IQ tests measure. So the IQ tests have separate parts that interrogate these separate abilities separately, but a person's ability in all of these areas is highly correlated. And one thing that's important to point out is that things didn't have to be this way.

In fact, it's intuitively plausible that if a person is going to be really good at math, say, that this ability could come at the cost of his being good at language or vice versa. But that's generally not the case. I mean, there's just a very strong case to be made for this factor of general intelligence. That's actually how it got started, was Charles Spearman, back in the beginning of the 20th century, a brilliant psychologist. Well, he noticed that it didn't make any difference what the test was for, whether it was for British history or algebra or how to fix a car or anything, no matter what the test was, as long as it tapped into something in the brain, the test score seemed to be correlated. That was his first insight. And his second insight was that the magnitudes of the correlation varied by tests. And then even before he invented factor analysis, he would look at the pattern of correlation and say, you know what? These tests seem to be clustering on something.

And then statistically, he invented a way of capturing that. So it was that it's that correlation. But Sam, other people are saying to themselves right now, wait a minute. And by the way, I could say this about myself. My verbal skills are way better than my math skills or vice versa. And that's true. But think of it in terms, since most of your listeners have taken SAT or other kinds of tests, think in terms of the comparative score on the SAT verbal versus the SAT math. And I bet, yes, there may very well have been a substantial difference between your two scores. There was between mine, but it's not that you were below

average in one and above average in the other. You were above average in both. You were just more above average in the other. And the same thing would be true if you were below average. Usually there are always exceptions. I have a close relative who is way up at the tippy tippy top on verbal and is way below average on math. But that's unusual enough that the psychologist who tested him said that in 30 years of testing people had never seen that before. By and large, you have the kinds of correlations you're talking about.

It's very well established. Yeah, and there are a few other wrinkles here. So there's people can be dyslexic and be very high in intelligence, but the dyslexia impedes their academic performance. And there are other aspects to human ability intellectually, like creativity and ambition, and there's just other things going on that explain a person's success academically or occupationally. Oh, let me throw in my very favorite analogy about the role of IQ in success.

Comes from Stephen Goldberg, who's a professor of sociology at, I think, City College of New York. It's great. He says the role of IQ in explaining success is IQ has the same role as weight does for offensive linemen in the NFL. He said if you take the starting linemen in the NFL and you correlate their productivity with their weight, the correlation is going to be basically zero because the heaviest linemen are not the best linemen. But you have to be 300 pounds to get the job. And that's the way with IQ. Motivation, what they now call grit, and a variety of other things are decisively important. But if you're going to be a theoretical

physicist, you have to weigh 300 pounds to begin with. And then among theoretical physicists, those other qualities will be really, really important in determining how good you are. Right. And the other piece we should put in here is that it's also one of the most robust findings in psychology at the moment, or I should say behavioral genetics, really, that IQ is highly heritable. It's somewhere in the range of 50% to 80%, depending on how old a person is. It actually seems to become more heritable the older we get, which is strange. I mean, there's this concept of genetic amplification where the boundary between genetic difference and environmental difference is kind of hard to draw because you can think of the fact that genetic tendencies early in life can lead to changes

in environment. So when we think about environment, we tend to think about the environment that gets imposed on a child by the parents or by society. But you also have to think about the things children choose to do with their lives and then increasingly do as adults. So if you become obsessed with computers and then go get a job at Google, well, then your environment has been shaped by what you have paid attention to, and what you have paid attention to and your aptitude, the underlying aptitudes that caused you to do that were, to a very significant degree, it seems, at least 50% dictated by the genes you inherited from your parents. Yeah, all of that is true. And it is also true that we are a long way from disentangling all of this, there are enough really good twin studies. And by that, I don't mean twins raised apart. I'm talking about the classic twin studies where you're comparing identical

twins with fraternal twins, which allows for some very useful and powerful disentangling of environment and genes. So are there gene environment interactions where to some degree a child creates his or her own environment that in turn reinforces the genetic material? Absolutely. Does that mean that if only you can jack up artificially the environment, you're going to make much difference in a child's IQ? And the answer to that is not long-term. You can get some short-term effects, but the problem of fade-out is universal. Yeah, so that's also another wrinkle here, which I think adds to people's concern about talking about this whole area, this lack of anything obvious to do about remedying any inequalities we find here. That's, I think, a major source of angst, and it's kind of a preamble to something

I'll be coming back to. There is this notion that if traits are genetically determined, that's bad. And if traits are environmentally determined, that's good because we can do something about them if they're environmental. And if there is one lesson that we have learned from the last 70 years of social policy, it is that changing environments in ways that produce measurable results

is really, really hard. And we actually don't know how to do it, no matter how much money we spend. Right. We should also, another background point here is that virtually everything important psychologically, most things that interest us psychologically about people, these traits are also highly heritable. This includes like the big five personality traits, extroversion, agreeableness, conscientiousness, neuroticism, and openness. A person's personality is also, at this point, about 50% ascribed to genetic inheritance and the rest to environment. Right, but here we get the wrinkle. We could talk forever. But anyway, I'll just throw

this in, that there is the shared environment and there's the non-shared environment. And that's one of the things that Twin Studies has elucidated. And it's the non-shared environment that takes up almost all of that 50% of personality characteristics that is not explained by genes. Non-shared environment can be all sorts of things. It can be you had different teachers in schools, you ran with different peer groups. It can also be that the parents treat children differently. So the warmth of maternal warmth that a mother shows toward one twin can and sometimes is much different than the warmth

shown to another. So, but the thing about the non-shared environment is it's not susceptible to systematic manipulation. It's idiosyncratic. It's non-systematic. There are no obvious ways that you can deal with the non-shared environment in the way that you could say, oh, we can improve the schools, we can teach better parenting practices, we can provide more money for whatever you want to provide money for. Those all fall into the category of manipulating the shared environment. And when it comes to personality, as you just indicated, it's 50-50, but almost all of that 50 is non-shared. Yeah, which seems to leave parents impressively off the hook for how their kids turn out. Although it is true that parents, and I'm a father of four, we resist that. And with the non-shared environment and the small role left for parenting, I will say it flat out.

I read that research with the most skeptical possible eye. I was looking for holes in it assiduously. This is Judith Rich Harris, right? Judith Rich Harris wrote a book on this topic, didn't she? Judith Harris, Judith Harris, yes. And that was back in the 1990s. And talk about, um, well, look, you said that you heard about the bell curve and didn't read it for a long time. I heard about her book and I didn't read it for a long time.

Funny how that happened. I did. I didn't want to believe it. And she was, was very sound it was very rigorously done and and at this point i don't know of anybody who's familiar with the literature who thinks there's that much of a role left of the kind that parents thought they had in shaping their children right well i'm not gonna stop trying i think it's it's a very hard illusion to cut through. As I read Harry Potter tonight to my eldest daughter. You know, but I think that it's good to reflect on that. Reading Harry Potter to your eldest daughter is a good in itself. Yeah. And the fact that she behaves differently 20 years from now is not the point. No, exactly. It is an intrinsic good, and it's for my own pleasure that I do it largely at this point. Again, I'm painfully aware, and I think our listeners will be, that we are proceeding

along a razor's edge in this conversation, and that my attempt to have it defensively is all too obvious. I want, given your experience and given just how combustible these issues are, I just want to make sure we're putting the relevant pieces in play when our listeners need to receive them. One thing that just occurred to me people should also understand is that in addition to the fact that IQ doesn't explain everything about a person's success in life and their intellectual abilities, the fact that a trait is genetically transmitted in individuals does not mean that all the differences between groups, or really even any of the differences between groups in that trait, are also genetic in origin. Right?

Critically important point. Yeah, so the jury can still be out on this topic, and we'll talk about that. But to give a clear example, so if you have a population of people that is being systematically malnourished, they might have genes to be as tall as the Dutch, but they won't be because they're not getting enough nourishment. And in the case that they don't become as tall as the Dutch, but they won't be because they're not getting enough nourishment. And in the case that they don't become as tall as the Dutch, it will be entirely due to their environment. And yet we know that height is among the most heritable things we've got. It's also like 60%

to 80% predicted by a person's genes. Right. The comparison we use in the book, which actually was drawn from Richard Lewontin, the geneticist, is that if you take a handful of genetically identical seed corn and divide it into two parts and plant one of those parts in Iowa and the other part in the Mojave Desert, you're going to get way different results. It has nothing whatsoever to do with the genetic content of the corn. Right, right. A more general way to talk about this is when genes are identical, any differences you see have to be due to environment, and when environment is identical, any differences you see have to be due to genes.

Yeah. Going through my head are things like measurement error and this and that and the other thing, but your basic point is correct. Right. And there are many other things that IQ is correlated with. High IQ is correlated with things like liberal values and things like being less racist and less authoritarian and less sexist, even less religious. I mean, in particular, less fundamentalist in your religiosity.

Now, that's not to say that there are not exceptions to every trend we would talk about. So I'm sure you can find a racist, sexist, Bible-thumping genius somewhere, but there won't be as many of these people. And the link between IQ and traits like that are also strong, but stronger for some others. But again, so there's this one piece, which is IQ itself having nothing to do with race has been a somewhat taboo topic, particularly on the left politically. But what's interesting is that it wasn't always the case because the left used to be kind of boosterish about IQ testing because it seemed to promise a direct road to meritocracy. It would get us out of these class differences and people could just be judged on their own merits. That's why the SAT was invented. The SAT was going to be, and in fact,

The SAT was going to be, and in fact, it did serve this function. It would be a way for kids who did not go to Groton and Exeter and the rest of it to get a chance to show how smart they were. And they could be brought into the colleges. And Harvard in particular and its president back in the 1940s were very hot on using tests for precisely that purpose. And by the way, I went to Harvard in 1961, which pretty well dates me, from Newton, Iowa. And I was absolutely convinced that I got in because I was able to take an SAT score and get a good score, even though I went to a mediocre public school. Sorry about that, Newton High School. And in that sense, the enthusiasm for IQ is appropriate insofar as it's a good way to identify intellectual talent. But at this point, Sam, it's almost as if we are in the opposite position of conventional

wisdom versus elite wisdom that we were, say, when Columbus was going to sail to America. When Columbus was going to sail to America, it is true that an awful lot of the ordinary people still thought that the Earth was flat. But among the elites, it was understood that the earth is round. Well, now it is ordinary people are perfectly comfortable with the idea that some people are smarter than others. They're perfectly comfortable that what we call smart gets you kinds of jobs that you can't get otherwise, all that kind of stuff. It's the elites who are under the impression that, oh, IQ tests only measure what IQ tests measure, and nobody really is able to define intelligence, and this and that, they're culturally biased, on and on and on and on. And all of these things are the equivalent of saying the earth is flat. These are not opinions that you can hold in contest with the scientific literature

any more than you can be an Aristotelian physicist in contradistinction to a Newtonian physicist. This stuff is not subject to debate anymore. But the elite wisdom now in colleges is, and a lot of your listeners are saying, what I'm saying is pseudoscience. It's very frustrating. Yeah, you just referenced two things which I think are widely believed, which are certainly known to be false, and were known to be false at the time you wrote your book, again, more than 20 years ago. And the first claim is that IQ tests simply measure people's ability to take IQ tests. That is a shibboleth that is rattling around the brains of certainly many of our listeners. No one in touch with the literature has thought that was true for a generation. And then there's the idea that

these tests are well known to be culturally biased so that you just cannot get valid data on certain groups. And this is something we've never been able to overcome. That also is not the current opinion of psychometricians anywhere. Is that correct? Yeah. And let me describe a little bit why we know those two things in terms of why we know that IQ tests measure something other than the ability to take an IQ test. If you'd like to continue listening to this conversation, you'll need to subscribe at SamHarris.org. Once you do, you'll get access to all full-length episodes of the Making Sense podcast, along with other subscriber-only content, including bonus episodes and AMAs and the conversations I've been having on the Waking Up app. The Making Sense podcast is ad-free

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