American IQ scores have rapidly dropped, proving the 'Reverse Flynn effect'

Honest question that keeps bothering me.

In the absence of reasonably strong natural selection pressure to select for IQ, how could IQ not be falling over time?

It is not. IQ doesn’t measure a kind of intelligence which inherits, and is subject to natural selection (there is even a debate whether such intelligence exists; or at least is of any significant between individuals).

IQ at best measures something that correlates with SAT. And with better education, less exposure to damaging pollutants, etc. it should always be on the rise (as demonstrated by the Flynn effect; an effect which this poor paper desperately tries to refute).

IQ research has always been about proving the superiority of one race over others, this superiority doesn’t exist, but that doesn’t stop these pseudo-scientist from trying. They bend the definition of “intelligence” and device test batteries (and in this case, interpret test battery) in skewed and bias ways to manipulate results like these. Regrettably media outlets like the Popular Mechanics and lifestyle journalists like Tim Newcomb take these researchers at their words and publish their results, despite their results pretty much being lies.

The heritability of IQ is very well established, usually estimated in the 50-80% range. You are fighting an uphill battle here because even if people haven’t seen the scientific evidence this effect is so strong that virtually everybody has seen anecdotal evidence of high IQ parents having high IQ children, but just seem to assert a very heterodox and counter-intuitive position without further elaboration.

It is incredibly arguable if during an obesity crisis if population wide health is actually improving and if population wide health isn’t improving that could certainly contribute to lower IQ. We’re also seeing population wide declines of health in other ways like sperm count. Food is becoming less nutritious as soil depletes. Our fish stocks being about to collapse is going to be another hit against brain health as omega 3s will become rarer in the diet.

I’m not fighting an uphill battle. Ever since The Bell Curve came out, there has been a slow but steady distancing of both psychological research and policy makers from the whole field of IQ research. Modern psychology couldn’t care less about on the heritability factor of IQ, and most policy makers don’t want to touch it with a 10 foot pole. Heck the SAT has even been renamed as they don’t want to be affiliated with anything resembling IQ any more.

The heritability of IQ is only well established within true believers of a pseudo-science tightly linked with the eugenics movement. Most psychologists today believe that the supposed heritability was observed because of bias within the research. And given the people who were doing these research in the 1970s and the 1980s, and their motivation for doing those, there is no question on what these biases were. Some of the researchers went so went quite far in bending the data such that it would fit their narrow—and racist—world view. They tried really hard to define intelligence such that it would make rich white people smarter, they were regrettably successful for far to long, but ultimately failed.

Your anecdotal evidence of high IQ parents (ugh!) having high IQ children is the same anecdotal evidence that sociologists have been describing for decades that high SES parents have high SES children, and is the main reason for why parents with high SAT scores are likely to have children with high SAT scores.

What IQ researchers discovered was basically the same thing that Marx described in 1867, class, however the eugenics were no communists, and instead of providing the simpler explanation, that society rewards the ruling elite, and wealth inherits, the eugenics went all conspiratorial and blamed other races for their perceived decline in society.

The following is my opinion, based on my research:

* IQ is real, measurable and heritable. The evidence for this is overwhelming.

* Nobody argues about the broad heritability of other human traits such as hair/eye color, height, athletic ability and the like.

* The argument over IQ is a consequence of terrible historical experiences with eugenics and racial discrimination. Many have adopted the quasi-religious viewpoint that IQ is not heritable to sidestep the discussion.

* As a consequence, social policy resembles the cycles and epicycles of Ptolemy's cosmology. Namely, all manner of social, economic and historical outcomes which are explained parsimoniously by understanding IQ as heritable are instead attributed to a Rube-Goldberg machine of racism, class warfare and the like.

* Accepting IQ as heritable does not, in an enlightened society, require acceptance of racism or classism, any more than people are forced to discriminate against those who, say, are genetically weaker athletes due to low relative VO2 levels.

* Social policy could be enhanced and better targeted by targeting those at the lower end of the IQ curve with subsidies such as basic income.

* Accepting IQ as real, heritable and measurable represents one of the only paths out of the present morass of corrupt political patronage programs around specific groups, just as rejection of Ptolemy's worldview enabled turning away from the demon-haunted world of religion.

People say IQ is "heritable" all the time, but it's easy to say that without giving any evidence that one understands what heritability means. Lots of things are heritable and not genetically determined, and there are things that are absolutely genetically determined that aren't really heritable.

If you're going to build a whole chain of logic, one that attempts to solve racism somewhere in the middle and ends with the "demon-haunted world of religion", it's useful to clearly define your terms first.

I was using "heritable" as a synonym for "genetically determined." Thanks for the clarification. To be a bit more specific, it is obviously possible to environmentally lower someone's IQ from their genetic potential. Examples include lead poisoning and denial of basic nutrition. Similarly, you can environmentally prevent someone from being able to run as fast as they might genetically have been able to by injuring their legs in various ways in childhood.

in both of those cases, as in all things genetic, expanding the ceiling is a far different matter. There is no known treatment I could have been given to enable me to run a 2 hour marathon. Similarly, there is no known way to cause a 100-IQ person to reliably test at a 140 IQ.

That said, progress is being made on artificial intelligence and genetics, so that could all change.

I don't understand how your logic holds together once you concede that heritability doesn't mean "genetically determined". This is the problem with lots of arguments about "heritability" of IQ; heritability is simply the ratio of genetic effects to the total variance in a population. If we're asking whether IQ is genetic, then saying that something is "highly heritable" is simply restating the question.

(I find it helpful to remember that lipstick-wearing is highly heritable despite zero genetic determination, and number of toes isn't very heritable at all despite total genetic determination.)

In particular, you can't convincingly go from discussing the seemingly profound effects acknowledging IQ heritability will have on racism, in order to avoid "demon-haunted" religious arguments, to a shrug and a handwave about genotypic (and epigenetic) effects vs. environmental effects. With due respect to your good-faith attempt to establish a logical baseline to this whole situation, the demons are haunting your argument, not those of people who'd push back on it.

It's an earlier rebuttal and you can find more precise and current ones now, but Ned Block's heritability piece is a good starting point for this stuff (you can just Google for "ned block heritable", the SERP will be dozens of links to it.)

Your first sentence is a complete misread of my comment, so I'm not going to reply. I said exactly the opposite of what you claim I said. Please re-read what I wrote and try again.

Edit:

I read a bit of Ned Block's piece. I believe he more or less immediately dismisses my view as "Extreme geneticism". While I don't agree that different groups in a given country grow up in the same circumstances, I also don't believe this matters much, if at all. If life teaches anything, it's that it's incredibly difficult to construct a machine that absolutely prevents the success of one group or another. Life is diverse and adaptable and finds a way. There are plenty of examples of groups historically facing terrible environments who nonetheless prospered.

Block also complains about a lack of sufficient data on the question of IQ. Fine, but one must immediately ask why there is such a lack of data. And that returns us to the demon-haunted world of quasi-religious opposition to such research.

Bottom line is, if you want to argue for the Rube Goldberg machine of -isms that produce differential outcomes in groups, prove it. I believe that, just as in other areas of human endeavor such as athletics, the prior should be that genetics are the most important input.

You should read all of Ned Block's piece. It's very good.

He is not just dismissing your view as "extreme geneticism". He literally explains how fallacious it is to conflate heritability with genetic determination. Using that to make judgments about genetic determination of IQ is therefore methodologically flawed and the only intellectual honest course of action is to dismiss these types of judgments outright.

It is interesting that you apply Occam’s razor now, but not when the question is whether we need IQ at all in our models. In a different post when asked about the utility of IQ you answered:

> In general, the goal is to quantify an individual's mental potential

But IQ researchers have been trying to do that for over half a century, and so far have yielded pretty limited results, especially compared to models from other fields such as cognitive psychology or neuropsychology, neither of which use IQ in their models. The principle of parsimony states that: “Entities must not be multiplied beyond necessity”. In modern psychology IQ is a useless entity.

However now you are talking about pedagogy or developmental psychology where IQ and other models of intelligence is still being used (though it is getting more and more fringe). Over there nobody cares about the heritability of IQ, only whether or not they predict certain learning disabilities and (and this is old school) which traits of intelligence predicts which learning outcomes (though I would argue behavioral psychologists that don’t use IQ nor intelligence have better luck with their models). Again, if you insist on Occam’s razor, and believe (IMO wrongly) that IQ is the preferred method then heritability should be left out of the model.

Now there is one more thing I’d like to address:

> I’d love to see such a selective demand for rigor applied to, say, studies that suggest secondary education makes a difference in outcomes.

I encourage you to read a study in developmental psychology or pedagogy. I assure you there is plenty of rigor applied. You won’t find any models that include heritability, because, like I said, scientists in the field don’t need that, so they skip it for the sake of simplicity. But what you’ll find are double blind studies, AB tests, descriptions of metrics to assess quality, descriptions of methods to assess disability, plenty of scrutiny over these methods, experiments that valuate these methods, theories which take into account seemingly successful methods, scrutiny of theories with nuanced evidence, scrutiny of methods with nuanced evidence, meta-analyses where theories are ripped apart, meta-analyses where the same theories are supported. Entering “Secondary education efficacy” actually yields over 5 million hits on Google Scholar. I call that a fairly well studied question.

Mostly I just want to make the argument below to see how/if you'll respond. In general, I just don't think you're arguing in good faith. The reason IQ isn't studied isn't because it's "not useful." It's because people who study it are systematically shunned by academia.

But here's the main point I want to make:

I find it sort of amazing that folks will twist themselves into pretzels to argue that IQ's genetic basis shouldn't be the prior. The majority of smart people I've talked to in life had a similar experience to me growing up. Namely, they remember very well just being "better" at school than other kids, even though their environments were similar and they didn't honestly try that hard. I specifically remember teachers lauding me in 2nd grade for how hard I worked, when honestly I was and am pretty lazy. I remember very well sitting in class in 7th grade, watching the same presentations by the teacher that all the other kids watched and then with zero studying getting 100% correct on the test while many of them struggled. And I remember going to many of their houses and seeing that their home environments were either equivalent or superior to mine.

Athletic kids have a very similar experience, by the way, when it comes down to running or jumping or other sports. They're just "better".

At base, the environmental argument boils down to something like this: "Anyone in the world could have beaten Magnus Carlsen to become world chess champion if they'd just had the proper environment." Such an argument is so obviously preposterous that the prior should absolutely be that it's false.

Another point: We already know IQ is genetic. Witness that the housecat and humans have vastly different IQs, and no cat will ever perform better on an IQ test than the median human. Again, the prior obviously should be that IQ is genetic.

And again, note that I'm simply pointing out what the PRIOR should be. Thus, it should be on YOU to provide evidence that the prior is wrong. It is insufficient to simply argue that not enough evidence exists to prove IQ is genetic, because that is the prior. The burden of proof is on YOU.

Your arguments boil down to simply gaslighting smart people that their life experience is somehow completely inaccurate, unrepresentative, or misinterpreted. If you really are making it in good faith, it leaves me wondering what in your life experience leads you to believe the genetic explanation should not be the prior. Did you do poorly in school? Did you grow up in such a privileged environment that you can't believe that people like me exist?