Also worth noting that you're picking largely smart and good faith contrarians here, whereas there are even more popular contrarians (weinstiens, Joe Rogan, etc.) who are even less reliably correct but way more popular. I'm always shocked by how certain people like that in the contrarian space have nearly no filter for bullshit so long as it's anti-consensus.
We've lost our faith. People, institutions, countries, organizations...all out of our control, falling apart, or paralyzed. I have yet to meet any WEIRD person who doesn't think themselves somehow isolated from The System, even if they can't define it. Add to that the lure of "speaking truth to power," and everyone can LARP as Martin Luther...or at least Woodward and Bernstein.
I usually think of contrarianism as being wrong most of the time but helping on the margin because it brings light to positions that are underrated due to social conformity factors. I think most meta-contrarians would admit that they’re wrong most of the time. It would be quite silly to take the meta contrarian point and think you are right most of the time just due to the philosophical literature on rational disagreement (or lack thereof).
Well it's a very hard question because of (1) the selection problem and (2) heterogeneous effects.
Engineers obv earn way more with a college degree than they would without it. So if you have a school that's half engineers and half english majors, you could estimate positive average effects even if the english majors aren't benefiting at all.
And then the marginal effects might not take general equilibrium effects into account. Like maybe right now you need a college degree to be a barista (so there are some returns to college), but if 20% fewer people got college degrees, then you wouldn't need one.
I went through this same process 15 years ago. My conclusions from 2009
"contrarianism is a cheap way of allowing ideological hacks to think of themselves as fearless, independent thinkers, while never challenging (in fact reinforcing) the status quo ...To sum up my current view: “contrarianism” is mostly contrary to reality, the “conventional wisdom” is probably wiser than the typical unconventional alternative, and “politically incorrect” views are almost always incorrect in every way: literally, scientifically and morally.
I think this is right, but there are also some contrarian views that have turned out to be correct in a big way, a couple of examples:
-Trump was not actually working with the Russians (this was pretty contrary to conventional wisdom for a long time)
-Non-pharmaceutical interventions (mask mandates, social distancing mandates, school closures) probably have near-zero effect on SARS/CoV2 transmission
-Bad US health outcomes are mostly not due to our lack of a socialized healthcare system
Tbh the pattern I see here is that contrarian arguments that buttress politically radical takes tend to turn out wrong but contrarian arguments that militate against more-radical takes are often right. But that last bit is probably a biased assessment on my part.
Neither Caplan's views on education or Hanson's views on medicine are described correctly. Caplan argues that signaling is the primary explanation for the wage premium, not that it's the only one. Education, especially primary and secondary, results in skill building and such especially for mathematics and English.
I came here to say the same thing. Caplan even clarifies this when discussing immigration and international adoption and how that can benefit foreign-borm children. He believes that education does make people better employees, but it is generally early education (the 3 Rs) that does that and the older one gets the more education is about signaling.
Caplan also says there are fairly substantial gains in certain abilities for people in certain majors. E.g., science majors get better at causal reasoning, social science majors get better at statistical reasoning, and humanists get better at close reading.
It's true that he claims that 80% of the gains from a college degree are due to signaling rather than human capital development, but he makes it clear that this is just a speculative estimate. If it were as low as 60%, I'm not sure he'd think this refutes his position. I think his main point is that a fairly substantial majority of the income premium from schooling is due to signaling.
I came across this post because it was linked in today's Bismarck post, I agree with the thesis but mainly want to thank your for sharing Natalia's piece on sleep as well as Jay M's post on race gaps. Both are excellent, I and I hadn't read either before. Seeing those made me realize I'd like for people I follow to more frequently share what they think is the best argument for/against a variety of topics.
The Joe M piece you cited isn't nearly enough to override the mountain of evidence against the gap being genetic. A few adoption studies with low n values doesn't discount that, while IQ correlates at r = .86 for identical twins, but between r = .19 and .24 for adoptees and their foster parents (Bluchard & McGue, 1981, pp. 1057-58).* We'd never see such if it were primarily environmental.
It's exactly like arguing for creationism versus evolution. You don't have the luxury of dismissing a small number of studies. You have to dismiss the overwhelming majority of gathered knowledge of entire fields.
Meant to write "NOT being genetic", or something else that'd convey the same meaning. Psrdon my errpr.
This is not to say that it is solely genetic, as we know environment certainly influences intelligence. But given that black and white Americans have been living in pretty similar environments on average,* yet the gap remains about the same as it was a hundred years ago, I feel confident in saying the source of the gap is either entirely or primarily genetic.
* It's difficult to believe there's a meaningful difference in either led exposure or the consumption of iodized salt between races in the same country.
I don't think the gap is the same as a hundred years ago. Someone else linked to evidence that the gap shrunk to around 10 IQ points rather than a full standard deviation. African Americans also used to be a much more rural population, and people who grow up in rural areas tend to have lower IQs.
The evidence against the gap narrowing is quite robust, especially seeing as how many of the things we know that lower general intelligence, such as abusive orphanages and iodine deficiency, are pretty much nonexistent in the First World:
This would only be relevant if black people and white people were in abusive orphanages and had iodine deficiency at different rates in America, and there's no reason to believe this was the case. Same thing with rates of lead exposure. Anti-knocking lead was the main source of lead exposure, and that hit everybody equally.
I disagree with most of the examples. details below.
but contrarianism is wrong many times, of course!
1. Caplan on education.
Caplan literature review on education isn't a "public intellectual polemic". but rather an in-depth literature review much more comprehensive than the one Atis linked to.
I think Atis never read Caplan book. and by error assumed it to be just some blog post shallow opinion. (which Caplan can produce of course!)
can one argue "my literature review is better than Caplan"? sure. but Caplan is no less qualified.
and the signalling theory is education isn't a fringe view either. it's an old debate in economics.
2. Scott Alexander Vs Hanson. turns out it's far from conclusive. Scott original refutation seems to have interpreted Hanson much more expansively than Hanson intended (per Hanson). they went back and forth 4 posts. I don't think it's very conclusive!
3. COVID lab Vs raccoon dogs.
first, great example of where the whole "trust boring autists" is irrelevant.
the "system" intentionally lied. boring autists where forced to toe the party line and social media companies censored any mention of lab leak.
Moreover, many of those "boring autists" themselves thought it might well be lab leak.
at the end, the lied enforced on us might've turned out to be true. but originally "the experts" lied shamelessly.
4. Guezy in sleep.
Guezy made TWO claims:
A. the main claim. the book "why we sleep " is dishonest, unreliable and can't be considered "science based"
this is what went viral. is still true. was never refuted.
B. Guezy "bro feeling" opinion:
"I don't think we really need that much sleep".
his personal opinion. not evidence based. and he changed his mind later.
5. genes and IQ.
this is a policed topic.
who in his right mind would trust Chinese citizens about the veracity of Xi Yinping thought?
if you work in a university, or any public institution, you cannot say that Racial gaps in intelligence are of genetic origin.
therefore, it's "boring autists on a leash with a gun pointed to their head" Vs free People.
this doesn't prove the hereditarians right. but the reliability of university employed experts here equals that of OJ Simpson lawyers.
the example cited on adoption says
"I conclude that, while much of the data is low quality and no conclusive judgments can be made, most of the data is compatible with a primarily environmental explanation of the gap.". no slam dunk.
it's a debate with many lines of evidence. this guy choose one of them and didn't find a smoking gun.
6. Caplan is not even wrong re mental illnesses. I agree. but a much weaker version of his view might be true.
TLDR.
1. contrarianism is high risk. lots of incorrect views. obviously don't start by trusting everything contrarians say.
2. lots of the "refuting examples" in the blog aren't convincing.
3. whenever the system enforces a view using censorship/penalties, it's no contest. I'm not trusting Pravda. even though it's sometimes telling the truth.
IQ, racial issues, lab leak etc.
enforced dishonesty.
the contrarians aren't always right. but they are your only honest source.
"Sam is right, yet I think he understates the problem. There are various topics where arguing for one side of them is inherently interesting, yet arguing for the other side is boring. There are a lot of people who read Austian economics blogs, yet no one reads (or writes) anti-Austrian economics blogs. " I'm not sure I agree with the example or the generalization from it (if it were true). In the vast majority of urban educated upper middle class social circles in America, doing things like arguing against the minimum wage will just get you subtle or not so subtle scowls. Admittedly, you (and I ) might lurk in corners of the internet where this is reversed. But even in the other subculture that we both probably asspciate with (Effective Altruism), the opposite is true. In fact, there are systematic reasons why we should expect center-left positions to be less true than they appear to be - given so much of the elite and urban mass affluent population wants badly not to stray from this part of the spectrum. But sure, if you find yourself in a very specific bubble, it's fair to take a haircut on the contrarian positions that dominate within that bubble.
I agree that social pressure opposes many of the contrarian views I've discussed. My claim is that there are some topics--e.g. opposing hereditarianism--where people don't want to write long essays opposing them. So if you're a person who doesn't follow issues carefully, you'll probably believe the mainstream view even if it's false, but if you do follow issues very carefully and read a lot of internet blogs, you'll be biased in favor of the contrarian view.
On the topic of hereditarianism I've come across people who've flat out told me they would oppose it even if it were factually correct. They don't want to debate it.
Many good points here but I wonder if you overestimate the reliability/objectivity of obsessive autists researching things? They may be better at getting at some truths than other people are, but may turn out to be worse in other respects.
Your understanding of the lab leak hypothesis is laughably naive. Your understanding of HBD is similar. I suppose in both situations its probably for the best that you stick to consensus since you don't seem able to evaluate the claims yourself.
I'm not going to venture a guess on whether contrarianism is wrong in general - I don't know. But I think your description of the racial gaps debate is inaccurate. First, the view that genetic factors partially explain racial inequality in cognitive ability is only contrarian in the broader society. According to the most recent surveys on the topic, a majority of intelligence researchers agree that genetic factors at least partly explain racial gaps in cognitive ability.
Second, I've read Jay's blog in detail and I do like it, but he relies on older studies with severe methodological shortcoming - studies with small sample sizes and unknown selection bias - and never confronts the newer, more compelling evidence that the gaps have a genetic origin. For that, I would recommend Russell Warne's In the Know or, if you want a short piece on the topic, then: https://gwern.net/doc/iq/2021-warne-2.pdf
I agree with you on contrarianism as a general principle being wrong, but I don't find the piece on the heritability of IQ gaps very convincing.
The main issue is that he overrates adoption studies. There are all kinds of confounding selection effects with adoption that we don't really understand. What kind of self-selection is at play with women who give their children up for adoption at birth? Is the selection the same for both black and white women? It doesn't seem implausible that there's positive selection for black women (because single motherhood is much more normalized in black communities, and black girls who want to go to college are more likely to give up their children for adoption) and negative selection for white women (because white women with low intelligence are more likely to get pregnant accidentally). The lower IQ of late-adopted black children is attributed to more time in less enriching environments, but maybe it's just that parents who lose custody of their children are less intelligent than parents who give them up for adoption.
With mixed-race children, what is the average intelligence of BMWF couples whose children get put up for adoption? BFWM? How does this vary in the US vs. Europe? Who knows? Without knowing the IQs of biological parents, it's hard to get much out of adoption studies.
He makes a big deal out of IQ gaps not widening in the MTAS study, but with the small sample size (16 white adoptees at T2!), the error bars are so wide that we can't really draw any conclusions from that. He actually acknowledges the error bars where it helps his case (the black-white gap in young biracial children was not statistically significant), but not where it hurts his case.
IMO classical twin studies are a better approach, and these indicate that an implausibly large black-white environmental gap (multiple standard deviations) is needed to explain the IQ gap without help from genetics.
What we do know, beyond any reasonable doubt, is that the popular, mainstream explanations for the black-white IQ gap are wrong. Controlling for parental income does not close the IQ gap. It does narrow the IQ gap, but this is predicted by the genetic hypothesis (because controlling for parental income also partially controls for parental IQ). It's not underfunded schools, because majority-black schools aren't actually underfunded, and because white children in majority-black schools have better test scores than black children in majority-white schools. It's not lead, because that's basically been a solved problem for 20 years, and the gap remains.
Serious, intellectually honest environmentalists, like Flynn, acknowledge that if the environmental hypothesis is correct, it must involve some kind of non-economic environmental "X factor" that has not yet been confidently identified.
Also worth noting that you're picking largely smart and good faith contrarians here, whereas there are even more popular contrarians (weinstiens, Joe Rogan, etc.) who are even less reliably correct but way more popular. I'm always shocked by how certain people like that in the contrarian space have nearly no filter for bullshit so long as it's anti-consensus.
We've lost our faith. People, institutions, countries, organizations...all out of our control, falling apart, or paralyzed. I have yet to meet any WEIRD person who doesn't think themselves somehow isolated from The System, even if they can't define it. Add to that the lure of "speaking truth to power," and everyone can LARP as Martin Luther...or at least Woodward and Bernstein.
I usually think of contrarianism as being wrong most of the time but helping on the margin because it brings light to positions that are underrated due to social conformity factors. I think most meta-contrarians would admit that they’re wrong most of the time. It would be quite silly to take the meta contrarian point and think you are right most of the time just due to the philosophical literature on rational disagreement (or lack thereof).
https://www.overcomingbias.com/p/best-case-contrarianshtml
But see also https://slatestarcodex.com/2013/06/09/all-debates-are-bravery-debates/ and https://www.overcomingbias.com/p/contrarian-excuseshtml and
I Lowkey think I read these and forgot and then subconsciously resaid them. My bad
As someone blessed/cursed with a contrarian nature, I agree. I can see flaws in anything, but actually building something? No.
I actually discussed this with Econ profs and afaict the evidence *for* benefits of education is mostly at high school level
This is for example a quote from a DM with someone who seems quite knowledgeable and is a verified econ prof (not caplan ofc)
Well it's a very hard question because of (1) the selection problem and (2) heterogeneous effects.
Engineers obv earn way more with a college degree than they would without it. So if you have a school that's half engineers and half english majors, you could estimate positive average effects even if the english majors aren't benefiting at all.
Hoxby has presented evidence in many papers that there are a lot of programs / schools (esp. for-profit programs) that have very low returns, e.g. https://www.nber.org/system/files/chapters/c13709/revisions/c13709.rev0.pdf
And then the marginal effects might not take general equilibrium effects into account. Like maybe right now you need a college degree to be a barista (so there are some returns to college), but if 20% fewer people got college degrees, then you wouldn't need one.
The FDA is incredibly slow in letting people try drugs for fatal diseases like mine: https://bessstillman.substack.com/p/please-be-dying-but-not-too-quickly . I think that’s an essentially contrarian opinion but it’s also one that many insiders seem to silently agree with.
I agree
I went through this same process 15 years ago. My conclusions from 2009
"contrarianism is a cheap way of allowing ideological hacks to think of themselves as fearless, independent thinkers, while never challenging (in fact reinforcing) the status quo ...To sum up my current view: “contrarianism” is mostly contrary to reality, the “conventional wisdom” is probably wiser than the typical unconventional alternative, and “politically incorrect” views are almost always incorrect in every way: literally, scientifically and morally.
Easy to tear down, hard to build up.
I think this is right, but there are also some contrarian views that have turned out to be correct in a big way, a couple of examples:
-Trump was not actually working with the Russians (this was pretty contrary to conventional wisdom for a long time)
-Non-pharmaceutical interventions (mask mandates, social distancing mandates, school closures) probably have near-zero effect on SARS/CoV2 transmission
-Bad US health outcomes are mostly not due to our lack of a socialized healthcare system
Tbh the pattern I see here is that contrarian arguments that buttress politically radical takes tend to turn out wrong but contrarian arguments that militate against more-radical takes are often right. But that last bit is probably a biased assessment on my part.
Yeah that seems plausible.
In what ways have these contrarian views “turned out to be correct in a big way”? Please, link away.
0 connections with Russians is just factually untrue and not even Trump says that.
This would also be the contrarian’s take if they spent too much time among contrarians.
Neither Caplan's views on education or Hanson's views on medicine are described correctly. Caplan argues that signaling is the primary explanation for the wage premium, not that it's the only one. Education, especially primary and secondary, results in skill building and such especially for mathematics and English.
I came here to say the same thing. Caplan even clarifies this when discussing immigration and international adoption and how that can benefit foreign-borm children. He believes that education does make people better employees, but it is generally early education (the 3 Rs) that does that and the older one gets the more education is about signaling.
Caplan also says there are fairly substantial gains in certain abilities for people in certain majors. E.g., science majors get better at causal reasoning, social science majors get better at statistical reasoning, and humanists get better at close reading.
It's true that he claims that 80% of the gains from a college degree are due to signaling rather than human capital development, but he makes it clear that this is just a speculative estimate. If it were as low as 60%, I'm not sure he'd think this refutes his position. I think his main point is that a fairly substantial majority of the income premium from schooling is due to signaling.
I came across this post because it was linked in today's Bismarck post, I agree with the thesis but mainly want to thank your for sharing Natalia's piece on sleep as well as Jay M's post on race gaps. Both are excellent, I and I hadn't read either before. Seeing those made me realize I'd like for people I follow to more frequently share what they think is the best argument for/against a variety of topics.
The Joe M piece you cited isn't nearly enough to override the mountain of evidence against the gap being genetic. A few adoption studies with low n values doesn't discount that, while IQ correlates at r = .86 for identical twins, but between r = .19 and .24 for adoptees and their foster parents (Bluchard & McGue, 1981, pp. 1057-58).* We'd never see such if it were primarily environmental.
It's exactly like arguing for creationism versus evolution. You don't have the luxury of dismissing a small number of studies. You have to dismiss the overwhelming majority of gathered knowledge of entire fields.
* Thanks, Russell T. Warne!
> The Joe M piece you cited isn't nearly enough to override the mountain of evidence against the gap being genetic.
Did you mean to write "against the gap being environmental" or "in favor of the gap being genetic"?
Meant to write "NOT being genetic", or something else that'd convey the same meaning. Psrdon my errpr.
This is not to say that it is solely genetic, as we know environment certainly influences intelligence. But given that black and white Americans have been living in pretty similar environments on average,* yet the gap remains about the same as it was a hundred years ago, I feel confident in saying the source of the gap is either entirely or primarily genetic.
* It's difficult to believe there's a meaningful difference in either led exposure or the consumption of iodized salt between races in the same country.
I don't think the gap is the same as a hundred years ago. Someone else linked to evidence that the gap shrunk to around 10 IQ points rather than a full standard deviation. African Americans also used to be a much more rural population, and people who grow up in rural areas tend to have lower IQs.
The evidence against the gap narrowing is quite robust, especially seeing as how many of the things we know that lower general intelligence, such as abusive orphanages and iodine deficiency, are pretty much nonexistent in the First World:
https://psycnet.apa.org/record/2012-24333-012
Iodine deficiency wasn't non-existent a century ago. Also, Rushton is unreliable: https://entitledtoanopinion.wordpress.com/2012/05/06/rushton-is-the-spengler-of-race-realism/
This would only be relevant if black people and white people were in abusive orphanages and had iodine deficiency at different rates in America, and there's no reason to believe this was the case. Same thing with rates of lead exposure. Anti-knocking lead was the main source of lead exposure, and that hit everybody equally.
I disagree with most of the examples. details below.
but contrarianism is wrong many times, of course!
1. Caplan on education.
Caplan literature review on education isn't a "public intellectual polemic". but rather an in-depth literature review much more comprehensive than the one Atis linked to.
I think Atis never read Caplan book. and by error assumed it to be just some blog post shallow opinion. (which Caplan can produce of course!)
can one argue "my literature review is better than Caplan"? sure. but Caplan is no less qualified.
and the signalling theory is education isn't a fringe view either. it's an old debate in economics.
2. Scott Alexander Vs Hanson. turns out it's far from conclusive. Scott original refutation seems to have interpreted Hanson much more expansively than Hanson intended (per Hanson). they went back and forth 4 posts. I don't think it's very conclusive!
3. COVID lab Vs raccoon dogs.
first, great example of where the whole "trust boring autists" is irrelevant.
the "system" intentionally lied. boring autists where forced to toe the party line and social media companies censored any mention of lab leak.
Moreover, many of those "boring autists" themselves thought it might well be lab leak.
at the end, the lied enforced on us might've turned out to be true. but originally "the experts" lied shamelessly.
4. Guezy in sleep.
Guezy made TWO claims:
A. the main claim. the book "why we sleep " is dishonest, unreliable and can't be considered "science based"
this is what went viral. is still true. was never refuted.
B. Guezy "bro feeling" opinion:
"I don't think we really need that much sleep".
his personal opinion. not evidence based. and he changed his mind later.
5. genes and IQ.
this is a policed topic.
who in his right mind would trust Chinese citizens about the veracity of Xi Yinping thought?
if you work in a university, or any public institution, you cannot say that Racial gaps in intelligence are of genetic origin.
therefore, it's "boring autists on a leash with a gun pointed to their head" Vs free People.
this doesn't prove the hereditarians right. but the reliability of university employed experts here equals that of OJ Simpson lawyers.
the example cited on adoption says
"I conclude that, while much of the data is low quality and no conclusive judgments can be made, most of the data is compatible with a primarily environmental explanation of the gap.". no slam dunk.
it's a debate with many lines of evidence. this guy choose one of them and didn't find a smoking gun.
6. Caplan is not even wrong re mental illnesses. I agree. but a much weaker version of his view might be true.
TLDR.
1. contrarianism is high risk. lots of incorrect views. obviously don't start by trusting everything contrarians say.
2. lots of the "refuting examples" in the blog aren't convincing.
3. whenever the system enforces a view using censorship/penalties, it's no contest. I'm not trusting Pravda. even though it's sometimes telling the truth.
IQ, racial issues, lab leak etc.
enforced dishonesty.
the contrarians aren't always right. but they are your only honest source.
"Sam is right, yet I think he understates the problem. There are various topics where arguing for one side of them is inherently interesting, yet arguing for the other side is boring. There are a lot of people who read Austian economics blogs, yet no one reads (or writes) anti-Austrian economics blogs. " I'm not sure I agree with the example or the generalization from it (if it were true). In the vast majority of urban educated upper middle class social circles in America, doing things like arguing against the minimum wage will just get you subtle or not so subtle scowls. Admittedly, you (and I ) might lurk in corners of the internet where this is reversed. But even in the other subculture that we both probably asspciate with (Effective Altruism), the opposite is true. In fact, there are systematic reasons why we should expect center-left positions to be less true than they appear to be - given so much of the elite and urban mass affluent population wants badly not to stray from this part of the spectrum. But sure, if you find yourself in a very specific bubble, it's fair to take a haircut on the contrarian positions that dominate within that bubble.
I agree that social pressure opposes many of the contrarian views I've discussed. My claim is that there are some topics--e.g. opposing hereditarianism--where people don't want to write long essays opposing them. So if you're a person who doesn't follow issues carefully, you'll probably believe the mainstream view even if it's false, but if you do follow issues very carefully and read a lot of internet blogs, you'll be biased in favor of the contrarian view.
On the topic of hereditarianism I've come across people who've flat out told me they would oppose it even if it were factually correct. They don't want to debate it.
Many good points here but I wonder if you overestimate the reliability/objectivity of obsessive autists researching things? They may be better at getting at some truths than other people are, but may turn out to be worse in other respects.
Your understanding of the lab leak hypothesis is laughably naive. Your understanding of HBD is similar. I suppose in both situations its probably for the best that you stick to consensus since you don't seem able to evaluate the claims yourself.
I'm not going to venture a guess on whether contrarianism is wrong in general - I don't know. But I think your description of the racial gaps debate is inaccurate. First, the view that genetic factors partially explain racial inequality in cognitive ability is only contrarian in the broader society. According to the most recent surveys on the topic, a majority of intelligence researchers agree that genetic factors at least partly explain racial gaps in cognitive ability.
https://www.sciencedirect.com/science/article/pii/S0160289619301886
Second, I've read Jay's blog in detail and I do like it, but he relies on older studies with severe methodological shortcoming - studies with small sample sizes and unknown selection bias - and never confronts the newer, more compelling evidence that the gaps have a genetic origin. For that, I would recommend Russell Warne's In the Know or, if you want a short piece on the topic, then: https://gwern.net/doc/iq/2021-warne-2.pdf
I agree with you on contrarianism as a general principle being wrong, but I don't find the piece on the heritability of IQ gaps very convincing.
The main issue is that he overrates adoption studies. There are all kinds of confounding selection effects with adoption that we don't really understand. What kind of self-selection is at play with women who give their children up for adoption at birth? Is the selection the same for both black and white women? It doesn't seem implausible that there's positive selection for black women (because single motherhood is much more normalized in black communities, and black girls who want to go to college are more likely to give up their children for adoption) and negative selection for white women (because white women with low intelligence are more likely to get pregnant accidentally). The lower IQ of late-adopted black children is attributed to more time in less enriching environments, but maybe it's just that parents who lose custody of their children are less intelligent than parents who give them up for adoption.
With mixed-race children, what is the average intelligence of BMWF couples whose children get put up for adoption? BFWM? How does this vary in the US vs. Europe? Who knows? Without knowing the IQs of biological parents, it's hard to get much out of adoption studies.
He makes a big deal out of IQ gaps not widening in the MTAS study, but with the small sample size (16 white adoptees at T2!), the error bars are so wide that we can't really draw any conclusions from that. He actually acknowledges the error bars where it helps his case (the black-white gap in young biracial children was not statistically significant), but not where it hurts his case.
IMO classical twin studies are a better approach, and these indicate that an implausibly large black-white environmental gap (multiple standard deviations) is needed to explain the IQ gap without help from genetics.
What we do know, beyond any reasonable doubt, is that the popular, mainstream explanations for the black-white IQ gap are wrong. Controlling for parental income does not close the IQ gap. It does narrow the IQ gap, but this is predicted by the genetic hypothesis (because controlling for parental income also partially controls for parental IQ). It's not underfunded schools, because majority-black schools aren't actually underfunded, and because white children in majority-black schools have better test scores than black children in majority-white schools. It's not lead, because that's basically been a solved problem for 20 years, and the gap remains.
Serious, intellectually honest environmentalists, like Flynn, acknowledge that if the environmental hypothesis is correct, it must involve some kind of non-economic environmental "X factor" that has not yet been confidently identified.