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Introduction

The concept of “genotypic IQ” (GIQ) refers to a theoretical genetic potential of IQ. Basically, GIQ is one’s IQ without any corresponding environmental insults, and of course it is due the interaction of many genes each with small effect (which is the justification for GWAS). This, though, is like the concept of true score. “A true score is the hypothetical average of a thousand parallel testings of someone’s intellectual abilities.” Nevertheless, this concept of GIQ is used by hereditarians to proclaim that “genotypic intelligence is deteriorating” (Lynn, 1998) and this is due to “dysgenic fertility“, which is “a negative correlation between intelligence and the number of children” (Lynn and Harvey, 2008: 112), while “genotypic IQ” is “Genotypic intelligence is the genetic component of intelligence and it is this that has been declining” (Lynn and Harvey, 2008: 113) or is the IQ they have if they have access to optimal environments. I will argue in this article why the concept of GIQ is nonsense.

What is GIQ?

So GIQ is the so-called genetic component of intelligence. This, of course, is based on the assumption that genes are causative for IQ. This is based on the assumption that, however weakly, heritability can tell us anything about genetic causation (it can’t).

Lynn (2015) talks about the GIQs of Africans, pygmies, and aborigines. He also claims that the IQ of African Americans is “solely genetically determined“, since it hasn’t changed in some 80 years. This claim, though, is false (Dickens and Flynn, 2006). Nevertheless, the claim of GIQ arises due to the assumption—which hasn’t been tested, nor can it—that IQ and other psychological traits are caused/influenced by genes. I have argued at length that this claim is false.

It seems that the only people discussing this concept are the usual suspects (Lynn, 2015, 2018; Woodley of Menie, 2015; Madison, Woodley of Menie, and Sanger, 2016; Kirkegaard, Lasker, and Kura, 2019; Piffer, 2023). The decline in so-called genotypic IQ is used as a cudgel to try to argue that “dysgenic effects” of low IQ women having more children is leading to this effect. Weiss (2021: 35) puts it like this:

If women with a low IQ give birth to their children earlier than women with a high IQ, the mean genotypic IQ of the population will also decrease (Comings 1996), even if the number of children in both population strata should be the same. If the number of children across the IQ distribution is not equal (Blake 1989), the next generation will have a different IQ distribution.

Quite obviously, the hereditarian claim of GIQ is that some individuals—and of course groups—are genetically more intelligent than others. Nevertheless, a women “with a low IQ” doesn’t have a low IQ due to genetics; if we think about the nature of IQ and the types of items on the test, we then come to the conclusion that these tests aren’t a test of one’s genetic potential for learning ability (as many have claimed), but it’s merely what one has been exposed to and learned.

We have also used this concept of GIQ to attempt to show that these genes we have found to be associated with IQ have been in decline. Cretan (2016)—in a paper titled “Was Cro-Magnon the Most Intelligent Modern Human?“—tries to argue that GIQ has decreased since Neolithic times, and that the decrease in height and brain size since then is expected, since they are moderately correlated. However, the so-called brain size increase seems to be an artifact (Deacon, 1990a, 1990b). Cretan (2016: 158-159) writes:

Genotypic” intelligence changes across millennia because the genetic variants, or alleles, that enable people to develop higher intelligence change their frequencies due to mutation and selection. Evolution by mutation and selection implies that at a certain selection pressure favoring higher intelligence, the genotypic intelligence of a population remains constant. At selection pressures below this break-even point, intelligence will decrease; at higher selection pressure, intelligence will increase. In the complete absence of selection, genotypic IQ will not remain constant.

As we can see, this concept of GIQ and the so-called decrease in it has been sounding hereditarian alarm bells for decades. People like Lynn and Jensen push eugenic ideals on the basis of low intelligence people having more children, pushing for a negative eugenic practice to prevent people with low IQ from having children. Jensen, in his infamous 1969 paper, was pretty much explicit with these aims, and then in 1970 he stated that heritability can tell use one’s genetic standing when it comes to intelligence. Richard Lynn, in his review of Cattell’s Beyondism, called for “realistically phasing out” certain populations, but that it wasn’t eugenic:

“Is there a danger that current welfare policies, unaided by eugenic foresight, could lead to the genetic enslavement of a substantial segment of our population?” – Jensen, 1969: 95, How Much Can We Boost IQ and Scholastic Achievement?

“What the evidence on heritability tells us is that we can, in fact, estimate a person’s genetic standing on intelligence from his score on an IQ test.” – Jensen, 1970, Can We and Should We Study Race Difference?

…

“What is called for here is not genocide, the killing off of the populations of incompetent cultures. But we do need to think realistically in terms of “phasing out” of such peoples.” [Lynn]

This is an example of negative eugenics—preventing those who were thought to have undesirable traits from breeding. William Shockley—who was Arthur Jensen’s inspiration—talked about paying people to undergo sterilization. This was called the voluntary sterilization bonus plan:

Shockley is proposing varying bonuses to anyone with an IQ under 100 who agrees to be sterilized upon reaching child-bearing age. He would pay volunteers $1,000 for every IQ point below 100, with “$30,000 put into a trust fund for a 70-IQ moron, potentially capable of producing 20 children.”

…

Under the plan, bonuses would also go to potential parents based on the “best scientific estimates” of their having such “genetically carried disabilities as hemophilia, sickle cell anemia, epilepsy, Huntington’s chorea and so on,” with taxpayers getting no money to participate.

This is another example of negative eugenics, but there is of course also positive eugenics—encouraging those with desired traits to have more children. In his article Bright New World, Moen (2016) discusses this kind of positive eugenics, while endorsing the claim of GIQ. Moen proposed that women should be paid modest sums of cash to have children with high IQ sperm donors, not their husbands:

Here I would like to suggest an alternative way to raise global IQ: giving prospective mothers modest monetary incentives to have children that genetically belong not to their husbands (or to ordinary sperm donors) but to high-IQ sperm donors.

These are the kinds of views and ultimate consequences that derive from such thinking that there is GIQ. Since we know that IQ can’t be genetic, there can be no GIQ. If there can be no GIQ, then such proposals like these negative and positive eugenic ideas that I just cited would merely just be getting rid of people that are not socially desireable—mainly the lower class, along with blacks since they are more likely to be lower class and have lower IQs (due to knowledge exposure and differential access to cultural and psychological tools). This concept of GIQ has, since the advent of IQ tests in America, been used to sterilize people in the name of eugenics. The moral wrongness of eugenics is why we should reject this concept, nevermind the irreducibility arguments. Eugenic policies discriminate against people based on arbitrary criteria and violate their reproductive rights.

Arguments against GIQ

Now that I have described what GIQ is and how it has been used in the past in the name of eugenics, here are a few arguments to invalidate the concept.

P1: If IQ is solely determined by one’s genetic makeup, then IQ scores should remain stable through one’s lifetime.
P2: IQ scores do not remain relatively stable through one’s lifetime.
C: Thus, IQ is not solely determined by one’s genetic makeup.

P1: If IQ is solely determined by genetics, then individuals with high IQ parents should also have high IQ scores.
P2: If individuals with high IQ parents also have high IQ scores, then adoption should not affect their IQ scores.
P3: Adoption does affect the IQ scores of individuals with high IQ parents.
C: Thus intelligence is not solely determined by genetics.

This argument contradicts the main claim of GIQ, since adoption has been shown to raise IQ (see Capron and Duyme, 1989; Locurto, 1990; Flynn, 1993; Duyme, Dumaret, and Tomkiwicz, 1999; Kendler et al, 2015; see Nisbett et al, 2012 for review).

P1: If the concept of GIQ were true, then one’s IQ would be determined by their genetics.
P2: Genes don’t determine traits, nevermind psychological ones.
C: Therefore, the concept of GIQ is false.

P1: If psychological traits are reducible to genetics, then environment plays no role in shaping IQ and the concept of GIQ is true.
P2: The environment plays a significant role in shaping IQ, as adoption studies show.
C: Therefore psychological traits are not reducible to genetics and the concept of GIQ is false.

And

P1: If psychological traits are irreducible, then the concept of GIQ is false.
P2: Psychological traits are irreducible.
C: Therefore, the concept of GIQ is false.

Both of these argument draw on the irreducibility of the mental arguments I’ve been making for years. If the mental is irreducible to the physical, then the concept of GIQ can’t possibly be true.

P1: Either the concept of GIQ is true and implies that IQ is determined by genes alone, or the concept of GIQ is false and other factors other than genes contribute to IQ.
P2: If the concept of GIQ is true and implies genetic determinism, then it ignores the significant impact that environmental factors have on IQ and may perpetuate discrimination against those with low IQ.
P3: If the concept of GIQ is false and other factors other than genes contribute to IQ, then efforts should be focused on addressing these other factors rather than assuming that genes are the sole determinant of IQ.
C: Thus, either the concept of GIQ perpetuates discriminatory attitudes if true, or it distracts from addressing the true determinants of IQ if false.

P1 is logically true, while P2 and P3 are supported by scientific evidence, so the argument is plausible.

The concept of GIQ assumes that IQ is largely determined by genetics, and that individuals have different genetic potentials for IQ. There is no clear, consistent definition of intelligence. The factors that contribute to IQ are complex and multifaceted. So any attempt at reducing one’s IQ to their genes or to make predictions about one’s IQ from their genes along is inherently flawed and oversimplified. Thus, the concept of GIQ is not a valid or useful way of understanding intelligence, and so attempts to use it to make policy or social decisions would be misguided. So this argument challenges the concept of GIQ, since there is no accepted definition of intelligence. That’s more than enough to discount the concept entirely.

Conclusion

I have described the concept of GIQ that many hereditarians in the literature have espoused. It is described as one’s genetic potential for IQ sans environmental insults. The usual suspects are arguing for a GIQ. However as can be seen historically, this concept had led to destructive consequences for groups of people and individuals who are deemed less intelligent. It has been argued that those who have low IQs should not have children and that either people should be paid to not have children and get sterilized or to influence high IQ mother’s to have children not with their husbands but high IQ sperm donors. Eugenics is morally wrong so we should not do that, nevermind the fact that genes don’t work how hereditarians need them to. Nevertheless, I have given a few arguments that the concept of GIQ is misleading at worst and socially destructive at best. This is yet another reason why we should ban IQ tests.

Thus, the concept of GIQ is merely false eugenic nonsense.

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Introduction

Cold winters theory (CWT) attempts to explain the variation in IQ scores between countries. According to the theory, what explains a suite of observed differences is differential evolution by natural selection in different environments. Due to the exodus out of Africa, this led to the colonization of new biomes with novel things that early Man would not have been accustomed to. Thus, they would then need to be able to adapt their actions and behavior to their new environment. Since they were in novel environments, early man would then need to acquire new skills to survive. So those who could not, had a lower chance to reproduce, and so, there was selection-for and selection-against certain traits. So, over time, this led to differences in the phenotype between groups that evolved in different environments, and the driver of this was natural selection. Hereditarians have said as much, and this theory is a cornerstone to their thinking. The observed differences, in order to be of any use to hereditarians, must be due to evolution, particularly due to evolution by natural selection.

However, although natural selection isn’t itself a mechanism (Fodor, 2008; Fodor and Piattelli-Palmarini, 2010), it is generally understood that natural selection actually decreases genetic variation in a trait (Howe, 1997: 70; Richardson, 2017: 46) . Thus, if the differences in IQ between races were due to natural selection, then there would be decreased, not increased, variability in IQ/intelligence between races.

Emil Kirkegaard has a good overview of the history of this theory. Nevertheless, I myself have made critiques of CWT, which rely on the fact that it makes no risky, novel predictions (contra Lynn). In this article, I will mount some more arguments against CWT, and I will further show how the logic for the theory crumbles due to the use of shoddy reasoning and the use of ad hoc hypotheses to save the theory from falsification. I will conclude that the CWT has no scientific value and is nothing more than a just-so story that explains what it purports to explain while not successfully predicting novel evidence.

Cold winter theory – Lynn

One of the earliest instance of CWT can be found in Wallace (1864). In his article, he states things that contemporary hereditarians would then argue. In 1987, Richard Lynn argued that the selective pressures of cold winters explains the high IQs of “Mongoloids” (Asians) (Lynn, 1987). Lynn states that the higher IQs of Asians can be explained by the selective pressures of cold environments. He posits adaptations that evolved in Asians, which cold winter environments then selected-for. In 1991, Richard Lynn argued that surviving in novel environments that our species didn’t evolve in led to selective pressures which increased the IQs of “Caucasoids” and “Mongoloids.” The two groups had to survive in cognitively demanding environments and, due to the cold, needed to create shelters, make clothes and fire along with hunting game. So this explains why the two groups have evolved greater intelligence than Africans. Although Ian Deary is himself an IQ-ist, he rightly states that Lynn’s theory is nothing more than a just-so story:

Another review of the thorny issue which Lynn deals with in the first paper may be judged worthwhile if there is a wealth of convincing new evidence, or a Flynn-like (1987) fine-toothcombing of the past evidence. Neither of these objectives is achieved. Therefore, the Pandora’s box has been opened once more, some may say, to no great purpose. What of Lynn’s evolutionary account of the origins of intelligence test score differences between groups? It puts me in mind of Kipling’s Just So stories. When one is more used to examining factor analyses or anova tables the type of evolutionary evidence that is offered here is difficult to evaluate. One suspects that there is an infinite number of more or less plausible historical accounts of the causes of racial differences in IQ test scores, and that all would leave aside uncomfortable facts (like the intelligence needed to exist in hot arid climates). The issue addressed in Lynn’s first paper is difficult enough, but the evidence is far too sparse to be telling the story of how the eskimo got his/her flat nose. (Deary, 1991: 157)

Thus, if this relationship were to hold, then those who experienced the harshest, coldest conditions should have the highest IQs. However, this is not what we see. Arctic people have IQs around 91, and so, this seems to be a piece of evidence against CWT. Lynn, though, has an ad hoc hypothesis for why they don’t have higher IQs—they had a small population size and so high IQ generic mutations didn’t have a large chance to appear and then become stabilized in the genome like they did for Asians (population size for Arctic people 56,000; for Asians 1.4 billion; Lynn, 2006: 157). So due to geographic isolation along with a small population size, Arctic people did not have the chance to gain higher IQs. This is nothing more than an ad hoc hypothesis—an ad hoc hypothesis is produced “for this”, and a hypothesis is ad hoc if it cannot be independently verified. It’s a case of special pleading, as Scott McGreal’s argues.

The fact of the matter about CWT, is that the conclusion was known first (higher IQs in certain geographic areas), and then a form of reverse reasoning was used in order to attempt to ascertain the causes of the observed differences between groups. This is known as reverse engineering, where reverse engineering is defined as “a process of figuring out the design of a mechanism on the basis of an analysis of the tasks it performs” (Buller, 2005: 92). This is also one of Smith’s (2016: 227-228) just-so story triggers:

1) proposing a theory-driven rather than a problem-driven explanation, 2) presenting an explanation for a change without providing a contrast for that change, 3) overlooking the limitations of evidence for distinguishing between alternative explanations (underdetermination), 4) assuming that current utility is the same as historical role, 5) misusing reverse engineering, 6) repurposing just-so stories as hypotheses rather than explanations, and 7) attempting to explain unique events that lack comparative data.

Lynn (1990) attempted to integrate gonadotropin levels, testosterone and prostate cancer into the theory, stating that by having fewer children and showing mote care to them, non-African populations then shifted to a K strategy, which then led to a concomitant decrease in testosterone and subsequently aggressive tendencies (Rushton, 2000: 263). However, this is based on the false assumption that testosterone is directly responsible for aggression, meaning that as testosterone increases so does aggression. They have the cause and effect backwards, though—aggression leads to an increase in testosterone, so Lynn’s explanation fails.

Rushton then comes along and champions Lynn’s “contributions to science” (Rushton, 2012), while also praising Lynn’s theory as explain why northerly populations evolved higher IQs and larger brains than southerly populations (Rushton, 2005), while making the grandiose claim that “documenting global race differences in intelligence and analysing how these have evolved may be his crowning achievement” (Rushton, 2012: 855). Rushton wrote an Amazon review of Lynn’s book, and then again in the white nationalist magazine VDare. Of course Rushton would go to bat for Lynn, since Lynn’s theory is a cornerstone of Rushton’s r/K selection theory, which is where we will now turn.

Cold winter theory – Rushton

Starting in 1985, Rushton began arguing that there was a suite of dozens of traits that the races differed on (Rushton, 1985). He collated his arguments in his first book, Race, Evolution, and Behavior (Rushton, 1995), and he argued that what explained the differences in these traits between his races were the selective factors that influenced and dictated survival in those environments. Rushton and Jensen (2005: 265-266; cf Andrade and Redondo, 2019) argued that there are genetically-driven differences in IQ scores between races (blacks and whites, in this instance), and one of the largest reasons for these differences was the different types of environments the two races were exposed to:

Evolutionary selection pressures were different in the hot savanna where Africans lived than in the cold northern regions Europeans experienced, or the even colder Arctic regions of East Asians. These ecological differences affected not only morphology but also behavior. It has been proposed that the farther north the populations migrated out of Africa, the more they encountered the cognitively demanding problems of gathering and storing food, gaining shelter, making clothes, and raising children successfully during prolonged winters (Rushton, 2000). As these populations evolved into present-day Europeans and East Asians, the ecological pressures selected for larger brains, slower rates of maturation, and lower levels of testosterone—with concomitant reductions in sexual potency, aggressiveness, and impulsivity; increases in family stability, advanced planning, self-control, rule following, and longevity; and the other characteristics listed in Table 3.

So this is where Rushton’s r/K selection comes in. He proposed that “some groups of people are more K selected than others” (Rushton, 1990: 137). So if some groups are more K selected than others, then some groups would have different trait values when compared to others, and this seems to support Rushton’s theory. However, Rushton’s theory can be explained environmentally, without appealing to genetics (Gorey and Cryns, 1995) and it also has not been independently replicated (Peregrine, Ember and Ember, 2003).

Devestating Objections to CWT

Objection 1: The fact of the matter is, when it comes to CWT, this is a perfect example of ideas and beliefs that shift with the time based on current observations. Aristotle argued that since the ancient Greeks had the middle geographic position between Asia and the rest of Europe, they were spirited and intelligent and therefore continued to be free while those who inhabited cold places like Europe lacked intelligence and skill, they had spirit while those in Asia were intelligent while being skilful in temperament, while also being subject to slavery. It was the Greeks who were right in the middle—they were just right, like Goldilocks—to have both all of the good and none of the bad traits they associated with those in other geographic locales. Meloni (2019: 42) cited one Roman officer who stated that recruitment of individuals from cold climates “as they had too much blood and, hence, inadequate intelligence. Instead, he argued, troops from temperate climates be recruited, as they possess the right amount of blood, ensuring their fitness for camp discipline (Irby, 2016).” This is solid evidence that who is or is not “intelligent” can and has changed with the times, along with other explanations of differences between people. This, then, proves the contingency of the concept of “more intelligent people”, and that people will marshal any kind of evidence for their pet theories at the time they have observed them and work backwards to form an argument, a kind of inference to best explanation. Thus, an evolutionary psychologist or IQ-ist transported back to antiquity would have formulated a different theory of intelligence, which obviously would have been at-odds with what they try to argue for today.

Objection 2: In 2019, I contrasted the CWT with the vitamin D hypothesis. I argued that there was one successful novel prediction made by the VDH—namely the convergent evolution of skin color in hominids that left Africa (Chaplan and Jablonski, 2009: 452), which was successfully predicted by Chaplan and Jablonski (2000). I wrote:

If high ‘intelligence’ is supposedly an adaptation to cold temperatures, then what is the observation that disconfirms a byproduct hypothesis? On the other hand, if ‘intelligence’ is a byproduct, which observation would disconfirm an adaptationist hypothesis? No possible observation can confirm or disconfirm either hypothesis, therefore they are just-so stories. Since a byproduct explanation would explain the same phenomena since byproducts are also inherited, then just saying that ‘intelligence’ is a byproduct of, say, needing larger heads to dissipate heat (Lieberman, 2015). One can make any story they want to fit the data, but if there is no prediction of novel facts then how useful is the hypothesis if it explains the data it purports to explain and only the data it purports to explain?

It is possible to think up any kind of story to explain any observation to give it an air of scientific objectivity. Of course it is possible to argue that other climates can select higher intelligence, as Anderson (1991), Graves (2002), and Flynn (2019) have argued. Sternberg, Grigorenko, and Kidd (2005) have also argued that it is possible to think of any kind of explanation/story for any kind of observed data. Nevertheless, the fact of the matter is this: There is no reason to accept the CWT, since there is no independent evidence for the theory in question.

Objection 3: If the Lynn-Rushton CWT were correct, then we would observe lower variation in IQ scores between whites and Asians, since it is well-accepted that natural selection reduced genetic variation in traits that are important for survival (Howe, 1997: 70; Richardson, 2017: 46). In the hereditarian conception, of course intelligence is important for survival, and so if the hereditarian argument for CWT is true, then we should observe lower variance in IQs in whites and Asians compared to blacks, but we don’t see this. (Also see Bird, 2020 for an argument against the hereditarian hypothesis, showing that there is no natural selection in blacks and whites on cognitive performance.)

Objection 4: Hereditarians have relied on the concept of heritability for decades. If T is highly heritable, then T has a genetic component and what explains the variance in T is genetics, not environment. Many critiques of the heritability concept have been mounted (eg Moore and Shenk, 2016), and they spell trouble for the hereditarian CWT and the hereditarian hypothesis as a whole. But these estimates are derived from highly confounded studies, and so the “laws” derived from them are anything but.

Objection 5: Rushton and Lynn posit that Asians are K- while Africans are r-selected. Rushton rightly stated that Africans endure endemic and infectious disease, which he wrongly stated was an r trait. He also stated that cold winters shaped K traits in Asians and European populations. However, based on the (accepted at the time) tenets of r/K selection, it would actually be Africans that are K and Asians that are r, since groups that move out of environments they evolved in and into new ones are freed from density-dependent control (Anderson, 1991: 59).

Objection 6: The irreducibility of the mental to the physical means that psychology can’t be an object of selection since it is not physical. Intelligence is posited as a psychological trait, so it cannot be selected. This is a devestating objection to not only the CWT but to most hereditarian hypotheses which reduce mental states to brain states or genes. Such irreducibility arguments make hereditarianism untenable.

Arguments against CWT

With all this being said, here are a few arguments derived from the discussions above. It is well-established that the CWT hardly had any evidentiary basis. It’s merely the argument of ideologues.

P1: If CWT were true, then there would be independent evidence for it.
P2: There is no independent evidence for the CWT.
P3: The correlation between race and IQ is better explained by social and environmental factors than by the CWT.
P4: The evidence cited in support of the CWT, including Lynn’s national IQ data, is fraudulent and lacks scientific rigor.
C: Therefore, the CWT is false.

Premise 1: This is a basic tenet of scientific explanation. Independent evidence refers to evidence not used in the construction of the hypothesis. The only evidence for CWT is the observation of differences in IQ between people that inhabit different geographic locations. So if CWT were true, it is entailed that there should be independent, novel evidence to support the hypothesis. It is evidence that isn’t based on the original assumptions or data used to construct the hypothesis. If there is, then that raises the probability that the state of affairs that is proposed is true. Independent, novel evidence is important, since it helps confirm or disconfirm a theory or hypothesis by providing additional support from sources that were not originally taken into account. Evidence is novel when it is not already known or expected based on prior knowledge or previous observations. So novel evidence would, in this instance, refer to evidence that supports the theory and is distinct from the evidence that is used to support it. So in order for CWT to be scientifically valid, there would need to be independent evidence that shows a direct causal link between intelligence and cold winters.

Premise 2: This is a denial of the claim that there is independent evidence that supports CWT, on the accepted definition of “novel, independent evidence.”

Premises 3 and 4: These two premises are linked—access to education along with nutrition better explains the relationship between latitude and IQ. There is also the fact that Lynn’s “national IQs” are fraudulent (Sear, 2022). Thus, there is no evidentiary reason to accept Lynn’s IQs (the only reason is bias and that it “explains” the differing civilizational states of different races). It’s merely working backwards (returning to reverse engineering) since they have their conclusion in mind and then construct an argument to prove their already-held conclusion.

So the Conclusion follows—CWT is false since there is no independent, novel evidence for it. Therefore the only reason to believe it is bias in thinking against groups of people.

P1: The CWT suggests that differences in average IQ scores between racial groups can be largely explained by differences in the coldness of the winter climates that these groups evolved in.
P2: All of the evidence used to support the CWT is based on previously existing data, such as Lynn’s national IQ data or historical temperature records.
P3: There is no new independent evidence that supports the CWT beyond this existing data.
C: Thus, there is no novel, independent evidence for the CWT.

Or

P1: If there is new independent evidence for the CWT, then the CWT can be independently supported.
P2: There is no novel independent evidence for CWT beyond the existing data.
C: So the CWT cannot be supported by new independent evidence.

These arguments are valid and I hold them to be sound, based on the discussion in this article and my previous articles on the matter of CWT and the prediction of novel facts of the matter.

Conclusion

We don’t need evolutionary stories to explain IQ differences between countries (Wicherts, Borsboom, and Dolan, 2010). Lynn’s national IQ data is highly suspect and should not be used (Sears, 2022). High intelligence would be useful in all environments. The Rushton-Lynn CWT states that those who migrated to more northerly, colder biomes needed to plan ahead for the winter, and they would also need to plan and create hunting parties to procure food. This, of course, is ridiculous. Because you need to plan ahead to survive anywhere. Moreover, Will et al (2021) state that their:

analyses detected no such association of temperature with brain size. … These results suggest that brain size within Homo is less influenced by environmental variables than body size during the past 1.0 Ma.

This is of course a huge strike against the Rushton-Lynn CWT. Anthropological evidence also conflicts with the CWT (MacEachern, 2006).

Since I have shown that the evidentiary bases of the CWT doesn’t hold, then it isn’t logical to hold the belief that the CWT is true. Views like this are expressed in Rushton (2000: 228-231), Jensen (1998: 170, 434-436) and Lynn (2006: Chapters 15, 16, and 17). Since the main proponents of the model hold eugenist ideas, then it can be posited that they have underlying alterior motives for pushing this theory. Even a claim that there is “molecular genetic evidence” for CWT fails, due to, again, the irreducibility of the mental.

Nevertheless, there is no novel, independent evidence for the belief that cold winters shaped our minds and racial differences in psychological traits after the exodus out of Africa. There can be no evidence for it since we lack time machines and we can’t deconfound correlated traits. So these considerations point to the conclusion that the CWT is a mere story based on data which was then used to work backwards from an already-held conclusion. Thus, CWT is false.

Rushton, Lynn, Kanazawa (2008, 2012), (Kanazawa assumed a flat earth in his 2008 paper; Wicherts et al, 2012) Hart (2009), and Winegard, Winegard, and Anomaly (2020) therefore, are nothing more than just-so storytellers since they lack novel evidence for their assertions. So the so-called argument for evolutionary differences in intelligence/IQ rests on a house of cards that is simple to push over. The six objections laid out in this article are devestating for the CWT. There never was any evidentiary support for CWT—the kind that scientific hypotheses need in order to be valid, it’s merely an ideological series of statements, not an actual scientific hypothesis.

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Introduction

The hereditarian hypothesis posits that genetic/biological factors are responsible for IQ (“intelligence”) and other psychological traits. The claim is basically, IQ is heritable. It is heritable on the basis of twin, family and adoption studies, along with results from GCTA, GWAS and other newer tools that were created in order to lend credence to the twin, family and adoption estimates.

I have distinguished before between what I call “psychological hereditarianism” and “racial hereditarianism.” In this article, I will distinguish between the two more, and while psychological hereditarianism isnt necessarily racist, it can be used for racist aims.

Psychological hereditarianism

Psychological hereditarianism is the belief that psychological differences between people are due largely to genetic or biological factors rather than environmental ones. Claims such as this have been coming from twin studies for decades, and it has been commonly said that such studies have proven that aspects of our psychological constitution are genetically heritable, that is genetically transmitted.

Four kinds of studies exist which lend credence to psychological hereditarianism—family studies, twin studies, adoption studies, and GWAS.

Family studies

Family studies examine the similarities in individuals of the same family when it comes to their cognitive abilities (scores on IQ tests). These studies show that those who share more genes have similar scores than those who don’t. To the hereditarian, this is evidence for their hypothesis that genetic factors contribute to psychological traits and differences in them. Correlations are used to measure the strength of the relationship. An expected value of 50 percent (.5 correlation) between siblings is expected, as they share half of their genes. The correlation that is expected between unrelated individuals is 0, since they presumably don’t share genes (that is, they’re not from the same family).

However, there is one huge issue for family studies—environmental confounding. While people in the same families of course share the same genes, they also share the same environments. So family studies can’t be used as evidence for the psychological hereditarian hypothesis. Behavioral geneticists agree that these studies can’t be used for the genetic hypothesis for psychological traits, but they disagree with the implications of this claim for the next thing I will discuss.

Twin studies

Twin studies again use the correlation coefficient and compare twins raised together or “apart”, to then argue that genes play a substantial role in the etiology of psychological traits like “IQ.” These studies have found that identical twins have more similar cognitive abilities than fraternal twins, which to the twin researchers points to the conclusion that genetic factors contribute to substantially to psychological traits like IQ and other traits. However, the main limitation of such studies comes down to twins reared together. It is assumed that identical and fraternal twins share equally similar environments. This claim, as admitted by twin researchers themselves, is false (Joseph, 2014; Joseph et al, 2015). They then pivot to two arguments—Argument A and Argument B (Joseph et al, 2015)—but A is merely circular and B needs to be shown to be true by twin researchers, that is, they need to rule out and identify trait-relevant factors.

Limitations of twin studies include: not being generalizable to the general population; they’re based on many of the same (false) assumptions that were originally formulated on the 1920s at the advent of twin studies; the findings are misunderstood and blown out of proportion; they lead to volunteer/recruitment bias; and it doesn’t allow the disentangling of G and E since they interact (Sahu and Prasuna, 2016). The “advantages” of these studies aren’t even advantages, since it is conceptually impossible to tease out the relative contributions of G and E to a trait. Nevertheless, twin studies don’t show that psychological hereditarianism is true, and perhaps the most famous twin study of all—the MISTRA—hid the data of its fraternal twins (the controls). Joseph (2022) has an in depth critique of the MISTRA and why conclusions from it should be outright rejected.

Adoption studies

The issues with adoption studies are large, as large as the issues with twin studies. Assignment of adoptees to homes isn’t random, they look for homes that are closer to the homes of the biological mother. This restriction of range reduces the correlation between the adopted children and adopted parent. Adoptees also experience the womb of their biological mother’s (obviously). The adoptive parents are also given information about the adoptee’s family, and this along with conscious and unconscious treatment of the adoptee may help in making the adopted child different (see Richardson and Norgate, 2006; Moore, 2006; Joseph, 2014). Basically, the additive gene model is false, and adoptions don’t simulate a random design.

GWAS

The larger issue at hand here is how the aforementioned have been used to search the genome for the genes that lead to the high heritabilities of IQ. This has then led to the creation of polygenic scores. These studies examine the association between genes and IQ in large samples of individuals. These studies compare the genomes of people who have a certain trait, and they then look for correlations between the genes and the traits in that population. GWASs may miss rare genes with large effects. These studies only merely show associations between genes and traits, not causation. Another issue is population stratification—which is “differences in allele frequencies between cases and controls due to systematic differences in ancestry” (Freedman et al, 2004). GWAS, then, are compromised by this stratification, and attempts to correct for it have been found wanting (Richardson, 2017; Richardson and Jones, 2019; Richardson, 2022). There is also the fact that larger sample sizes won’t help the endeavor of proving that genes contribute to psychological traits—since large databases contain arbitrary correlations, then by increasing the sample size this then highly increases the chance for spurious correlations (Claude and Longo, 2017). At the end of the day, the associations found are weak and could possibly even be meaningless (Noble, 2018). There is also the fact that PGS ignore development and epigenetics (Moore, 2023). Basically, genes don’t work how hereditarians need them to.

The fact of the matter is, these research methods continue to push the false dichotomy of nature vs nurture (the first instance of which appeared in a 13th century French novel on gender). There is also the fact that the “laws of behavioral genetics” rest on twin, family and adoption studies. So if the assumptions of these studies are false, then there is no reason why we should accept the conclusions from them. There are no “laws” in biology, especially not the “laws of behavioral genetics.”

Racial hereditarianism

Racial hereditarianism, on the other hand, is the belief that there are inherent, genetic differences in cognitive ability and other psychological traits between racial and ethnic groups. One—most often unstated—claim is that one group of people are inferior to another (as can be evidenced by the labels of the categories used by Terman), and it has been used to justify discriminatory policies and forced sterilization of people found to have lower IQs. Genetic inheritance explains the how and why of some races having higher IQs than others.

The most famous racial hereditarians are Lynn, Rushton, and Jensen. Over the last 50+ years, these authors have dedicated their lives to proving that certain racial groups have higher IQs than others for genetic reasons. These differences aren’t due just to environment or culture, they say, there is a significant genetic component to the differences in scores between racial and ethnic groups. Since IQ is related to success in life—that is, since IQ is needed for success—then what explains average life outcomes between racial and ethnic groups are their IQs and the ultimate cause is their genes which ultimately cause their IQ scores. Due to the strength of genetic factors on IQ, they say (like Jensen), social programs are doomed to fail.

The argument against psychological hereditarianism and racial hereditarianism

The argument against these is simple—the mental is irreducible to the physical and so, while there are of course correlations between “traits” like IQ and genes, that doesn’t mean they’re causal and due to the irreducibility of the mental to the physical, we can’t find what they need us to find in order to prove their theses.

P1: If racial hereditarianism is true, then cognitive differences between racial groups are primarily due to genetic factors.
P2: There is no empirical (or logical) evidence that supports the claim that cognitive differences between racial groups are primarily due to genetic factors.
C: Thus, racial hereditarianism is false.

P1: If psychological hereditarianism is true, then individual differences in psychological traits are due primarily to genetic factors.
P2: There is no empirical (or logical) evidence that supports the claim that individual differences in psychological traits are primarily due to genetic factors.
C: Thus, psychological hereditarianism is false.

The irreducible complexity of mental states/psychological traits means that it’s impossible for them to be caused or influenced by genetics meaning that both psychological and racial hereditarianism are false. Both psychological and racial hereditarianism, as their unstated assumptions, rely on a type of physicalism to where mental states can be reduced to genes or the brain/brain states. Both kinds are a physicalist theory of mind, and since physicalism is false so are psychological and racial hereditarianism. This is yet more evidence that hereditarianism is false and so it strengthens the argument for banning IQ tests.

Conclusion

Both forms of hereditarianism I’ve discussed here are false, and ultimately they are false since the mental is reducible to the physical. Both of them, however, are inherently reductionist and attempt to reduce people to their genes or their brains. They have, in the past, led to the sterilization of certain people deemed “unfit.” Of course, the hereditarian hypothesis isn’t necessarily racist, though it can be used for racist aims. It can also be used for classist aims. It can be launched at whatever a society deems “unfit”, and then they can try to correlate biological factors with what they deem “unfit.” The very notion that certain races are superior or inferior on intelligence is a form of racism. Such ideas have been used in the recent past in order to justify discriminatory policies against people. So while the psychological hereditarian hypothesis may not be racist (it could be classist, though), how it has been articulated and then even put into practice is inherently racist. In any case, here’s the argument that the hereditarian hypothesis is a racist hypothesis.

P1: If the hereditarian hypothesis is true, then differences in IQ and other traits among racial and ethnic groups are primarily due to genetic factors rather than environmental or social factors.
P2: Differences in IQ and other traits among racial and ethnic groups are not primarily due to genetic factors, but rather environmental or social factors.
C1: Therefore, the hereditarian hypothesis is not true.
P3: If the hereditarian hypothesis is not true, then it cannot be used to make claims about inferiority or superiority.
P4: The hereditarian hypothesis has, historically been used to make claims about the innate superiority or inferiority of certain racial groups, thereby justifying discriniminatory policies and harmful stereotypes.
C2: Therefore, the hereditarian hypothesis is a racist hypothesis.

I’ve shown how P1 and P2 are true exhaustively, so C1 follows from those 2 premises. P3 follows from the conclusion in C1, and P4 is a historical fact. So C2 follows. So by referring to the hereditarian hypothesis as a racist hypothesis, I mean that the hypothesis has been entangled with racist and discriniminatory policies since it’s inception.

So I have articulated a distinction between psychological and racial hereditarianism, where psychological hereditarianism is about the genetic transmission of psychological traits and where racial hereditarianism is the belief that there are inherent racial differences in psychological traits due to genetic differences between groups. While there are of course genetic differences between groups and individuals, it doesn’t follow that said genetic differences cause differences in psychological traits, which is the main claim of hereditarianism. The issue of the reducibility of the mental isn’t an empirical matter, it’s a conceptual one. So the hereditarian hypothesis, therefore, is refuted on conceptual, a priori grounds.