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Introduction

For decades, hereditarians have attempted to partition traits into relative genetic and environmental causes. The assumption here is of course that G and E are separable, independent components and another assumption is that we can discover the relative contribution of G and E by performing certain tests and statistical procedures. However, since Oyama’s publication of The Ontogeny of Information in 1985, this view has been called into question. The view that Oyama articulated is a philosophical theory based on the irreducible interactions between all developmental resources called developmental systems theory (DST)

However, we can go further. We can use the concept of dualism and argue that psychology is irreducible to the physical and so it’s irreducible to genes. We can then use the concepts laid forth in DST like that of gene-environment and the principle of biological relativity and argue that the development of organisms is irreducible to any one resource. Then, for the formation of mind and psychological traits in humans, we can say that they arise due to human-specific ecological contexts. I will call this view Dualistic Experiential Constructivism (DEC), and I will argue that it invalidates any and all attempts at partitioning G and E into quantifiable components. Thus, the hereditarian research program is bound to fail since it rests on a conceptual blunder.

The view that refutes the claim that genes and environment, nature and nurture, can’t be separated is this:

(1) Suppose that there can be no environmental effect without a biological organism to act on. (2) Suppose there can be no organism outside of its context (like the organism-environment system). (3) Suppose the organism cannot exist without the environment. (4) Suppose the environment has certain descriptive properties if and only if it is connected to the organism. Now here is the argument.

P1: If there can be no environmental effect without a biological organism to act on, and if the organism cannot exist without the environment, then the organism and environment are interdependent.
P2: If the organism and environment are interdependent, and if the environment has certain descriptive properties if and only if it is connected to the organism, then nature and nurture are inseparable.
C: Thus, nature and nurture are inseparable.

Rushton and Jensen’s false dichotomy

Rushton and Jensen (2005) uphold a 50/50 split between genes and environment and call this the “hereditarian” view. On the other side is the “culture-only” model which is 0 percent genes and 100 percent environment regarding black-white IQ differences. Of course note the false dichotomy here: What is missing? Well, an interactive GxE view. Rushton and Jensen merely put that view into their 2-way box and called it a day. They wrote:

It is essential to keep in mind precisely what the two rival positions do and do not say—about a 50% genetic–50% environmental etiology for the hereditarian view versus an effectively 0% genetic–100% environmental etiology for the culture-only theory. The defining difference is whether any significant part of the mean Black–White IQ difference is genetic rather than purely cultural or environmental in origin. Hereditarians use the methods of quantitative genetics, and they can and do seek to identify the environmental components of observed group differences. Culture-only theorists are skeptical that genetic factors play any independently effective role in explaining group differences.

Most of those who have taken a strong position in the scientific debate about race and IQ have done so as either hereditarians or culture-only theorists. Intermediate positions (e.g., gene–environment interaction) can be operationally assigned to one or the other of the two positions depending on whether they predict any significant heritable component to the average group difference in IQ. For example, if gene–environment interactions make it impossible to disentangle causality and apportion variance, for pragmatic purposes that view is indistinguishable from the 100% culture-only program because it denies any potency to the genetic component proposed by hereditarians.

Rushton and Jensen did give an argument here, here it is formalized:

P1: Gene-environment interactions make it impossible to disentangle causality and apportion variance correctly.
P2: If it is impossible to disentangle and apportion variance, then the view denying any potency to the genetic component proposed by hereditarians becomes indistinguishable from a 100% culture-only perspective.
C: Thus, for pragmatic purposes, the view denying any potency to the genetic component is indistinguishable from a 100% culture-only program.

This argument is easy enough to counter. Rushton and Jensen are explicitly putting the view that refutes their whole research program into their 2 boxes—their 50/50 split between genes and environment, and the 0 percent genes and 100 percent environment. The view that Rushton and Jensen articulated is basically a developmental systems theory (DST) view. DST highlights the interactive and dynamic nature of development. Rushton and Jensen’s view is clearly gene-centric, where gene-centric means centered on genes. I would impute to them—based on their writings—that genes are a sufficient, privileged cause for IQ, and traits as a whole. But that claim is false (Noble, 2012).

Although I understand where they’re coming from here, they’re outright wrong.

Put simply, they need to put everything into this box in order to legitimatize their “research.” Although I would be a “culture-only theorist” to them regarding my views on the cause of IQ gaps (since there is no other way to be), my views on genetic causation are starkly different than theirs are.

Most may know that I deny the claim that genes can cause or influence differences in psychological traits between people. (And that genes are outright causes on their own, independent of environment.) I hold this view due to conceptual arguments. The interactive view (of which is more complex than Rushton and Jensen are describing), is how development is carried out, with no one resource having primacy over another—a view called the causal parity thesis. This is the principle of biological relativity (Noble, 2012). This theory asserts that there is no privileged level of causation, and so if there is no privileged level of causation, then that holds for all of the developmental resources that interact to make up the phenotype. Thus, hereditarianism is false since hereditarianism privileges genes over other developmental resources when no developmental resource is privileged in biological systems.

Rushton and Jensen almost had it—if GxE makes it hard or impossible to disentangle causality and apportion variance, then the hereditarian program cannot and will not work since, basically, they apportion variance into G and E causes and claim that independent genetic effects are possible. However, many authors have a conceptual argument on heritability, for if G and E and anything else interact, then they are not separable, and if they are not separable, they are not quantifiable. For example, Burt and Simon (2015: 107) argue that the “conceptual model is unsound and the goal of heritability studies is biologically nonsensical given what we now know about the way genes work.”

When it comes to “denying potency” to the “genetic component”, Rushton and Jensen seem to be quite specific in what they mean by this. Of course, a developmentalist (a GxE supporter) would not deny that genes are NECESSARY for the construction of the phenotype, though they would deny the PRIMACY that hereditarians place on genes. Genes are nothing special, they are not special resources when compared to other resources.

Of course, hereditarianism is a reductionist discipline. And by reductionist, I mean it attempts to break down the whole to the sum of its parts to ascertain the ontogeny of the desired object. Reductionism is false, and so that would apply to genetic and neuroreduction. Basically, reducing X to genes or the brain/brain physiology is the wrong way to go about this. Rushton (2003) even explicitly stated his adherence to the reductionist paradigm in a small commentary of Rose’s (1998) Lifelines. He repeats his “research” into brain size differences between races and argues that, due to the .4 correlation between MRI and IQ, due to differences in brain size between races (see here for critique) and since races have different cognitive abilities, then this is a “+” for reductionist science.

Since the behavioral genetic research program is reductive, it is necessarily committed to genetic determinism, even though most don’t explicitly state this. The way that Rushton and Jensen articulated the GxE (DST) view fit into their false dichotomy to try to reject it outright without grappling with its implications for organismal development. Unfortunately for the view put forth by Rushton and Jensen, organisms and environment are constantly interacting with each other. If they constantly interact, then they are not separable. If they are not separable, then the distinction made by Rushton and Jensen fails. If the distinction made by Rushton and Jensen fails, then ultimately, the quest of behavioral genetics—to apportion variance into genetic and environmental causes—fails.

Another hereditarian who tries to argue against interactionism is Gottfredson (2009) with her “interactionism fallacy.” Heritability estimates, it is claimed, can partition causes of variance between G and E components. Gottfredson—like all other hereditarians, I claim—completely misrepresent the view and (wilfully?) misunderstand what developmental systems theorists are saying. People like Rushton, Jensen, and Gottfredson quite obviously claim that science can solve the nature-nurture debate. The fact of the matter that destroys hereditarian assumptions and claims about the separability of nature and nurture is this: The genome is reactive (Fox-Keller, 2014) that is, it reacts to what is occurring in the environment, whether that be the environment outside or inside of the body.

At the molecular level, the nurture/nature debate currently revolves around reactive genomes and the environments, internal and external to the body, to which they ceaselessly respond. Body boundaries are permeable, and our genome and microbiome are constantly made and remade over our lifetimes. Certain of these changes can be transmitted from one generation to the next and may, at times, persist into succeeding generations. But these findings will not terminate the nurture/nature debate – ongoing research keeps arguments fueled and forces shifts in orientations to shift. Without doubt, molecular pathways will come to light that better account for the circumstances under which specific genes are expressed or inhibited, and data based on correlations will be replaced gradually by causal findings. Slowly, “links” between nurture and nature will collapse, leaving an indivisible entity. But such research, almost exclusively, will miniaturize the environment for the sake of accuracy – an unavoidable process if findings are to be scientifically replicable and reliable. Even so, increasing recognition of the frequency of stochastic, unpredictable events ensures that we can never achieve certainty. (Locke and Pallson, 2016)

The implication here is that science cannot resolve this debate, since “nature and nurture are not readily demarcated objects of scientific inquiry” (Locke and Pallson, 2016: 18). So if heritability estimates are useful for understanding phenotypic variation, then the organism and environment must not interact. If these interactions are constant and pervasive, then it becomes challenging—and I claim impossible—to accurately quantify the relative contribution of genes and environment. But the organism and environment constantly interact. Thus, heritability estimates aren’t useful for understanding phenotypic variation. This undermines the interpretability of heritability and invalidates any and all claims as to the relative contribution of G and E made by any behavioral geneticist.

The interactive view of G and E state that genes are necessary for traits but not sufficient for them. While genetic factors do of course lay the foundation for trait development, so do the other resources that interact with the genes (the suite of them) that are necessary for trait development. I can put the argument like this:

P1: An interactive view acknowledges that genes contribute to the development of traits.
P2: Genes are necessary pre-conditions for the expression of traits.
P3: Genes alone are not sufficient to fully explain the complexity of traits.
C: Thus, an interactive view states that genes are necessary pre-conditions for traits but not sufficient on their own.

Why my view is not blank slatism: On Dualistic Experiential Constructivism

Now I need to defend my view that the mind and body are distinct substances, so the mental is irreducible to the physical, so genes can’t cause psychology. One may say “Well that makes you a blank slatist since you deny that the mind has any innate properties.” Fortunately, my view is more complex than that.

I have been espousing certain points of view for years on this blog: The irreducibility of the mental, genes can’t cause mental/psychological traits, mind is constructed through interacting with other humans in species-relevant contexts to eventually form mind, and so-called innate traits are learned and experience-dependent. How can I reconcile these views? Doesn’t the fact that I deny any and all genetic influence on psychology due to my dualistic commitments mean I am a dreaded “blank slatist”? No it does not and I will explain why.

I call my view “Dualistic Experiential Constructivism” (DEC). It’s dualistic since it recognizes that the mind and body are separate, distinct substances. It’s experiential since it highlights the role of experiential factors in the forming of mind and the construction of knowledge and development of psychological traits. It is constructivist since individuals actively construct their knowledge and understanding of the world by interacting with other humans. Also in this framework is the concept of gene-environment interaction, where G and E interact to be inseparable and non-independent interactants.

Within the DEC framework, gene-environment interactions are influential in the development of cognition, psychology and behavior. This is because due to genes being necessary for the construction of humans, they need to be there to ensure they begin growing once conceived. Then, the system begins interacting irreducibly with other developmental interactants, which then begin to form the phenotype and eventually a human forms. So genes provide a necessary pre-condition for traits, but in this framework they are not sufficient conditions.

In Vygotsky’s socio-historical theory of learning and development, Vygotsky argued that individuals acquire psychological traits through interacting with other humans in certain social and environmental contexts through the use of cultural and psychological tools. Language, social interactions and culture mediate the cognitive development which then fosters higher-order thinking. Thus, Vygotsky’s theory highlights the dynamic and interactive nature of human development which emphasizes the social contexts of the actors in how mind is shaped and developed. So Vygotsky’s theory supports the idea I hold that mind is shaped through interactions and experiences within certain socio-historical contexts. So it would seem that adherence to this theory would mean that there are critical points in child development, where if the child does not get the rich exposure they need in order to develop their abilities, they then may never acquire the ability, indicating a critical window in which these abilities can be acquired (Vyshedakiy, Mahapatra, and Dunn, 2017). Cases of feral children allow us to see how one would develop without the role of social interaction and cultural tools in cognitive development. That these children are so stunted in their psychology and language shows the critical window in which children can learn and understand a language. The absence of social experiences in feral children thusly supports Vygotsky’s theory regarding the significance of cultural and social factors in shaping the mind. And cognitive development. Vygotsky’s theory is very relevant here, since it shows the necessary socio-historical and cultural experiences need to occur for higher order thinking, psychology, and mind to develop in humans. And since newborns, infants and young children are surrounded by what Vygotsky called More Knowledgeable Others, they learn from and copy what they see from people who already know how to act in certain social and cultural situations, which then develops an individual’s psychology and mind.

There is also another issue here: The fact that species-typical behaviors develop in reliable ecological contexts. If we assume this holds for humans—and I see no reason not to—then there need to be certain things in the environment that then jettison the beginnings of the construction of mind in humans, and this is in relevant social-historical-ecological contexts, basically, environments are inherited too.

In an article eschewing the concept of “innateness”, Blumberg (2018) has a great discussion on how species-typical traits arise. Quite simply, it’s due to the construction of species-specific niches which then allow the traits to reliably appear over time:

Species-typical behaviors can begin as subtle predispositions in cognitive processing or behavior. They also develop under the guidance of species-typical experiences occurring within reliable ecological contexts. Those experiences and ecological contexts, together comprising what has been called an ontogenetic niche, are inherited along with parental genes¹⁶. Stated more succinctly, environments are inherited—a notion that shakes the nature-nurture dichotomy to its core. That core is shaken still further by studies demonstrating how even our most ancient and basic appetites, such as that for water, are learned¹⁷. Our natures are acquired.

Contrasting the DEC with hereditarianism shows exactly how different they are and how DEC answers hereditarianism with a different framework. DEC offers an alternative perspective on the construction of psychological traits and mind in humans, and strongly emphasizes the role of individual experiences and environmental factors (like the social) in allowing the mind to form and shape psychological traits, but it does in fact highlight the need for genetic factors—though in a necessary, not sufficient, way. DEC suggests that genes alone aren’t enough to account for psychology. It argues that the mind is irreducible to the physical (genes, brain/brain structure) and that the development of psychological traits (and along with it the mind) requires the interactive influences of the individual, experiences, and environmental context.

There is one more line of evidence I need to discuss before I conclude—that of clonal populations living in the same controlled environment and what it does and does not show, along with the implications of behavioral genetic hereditarian explanations of behavior. Kate Laskowski’s (2022) team observed how genetically identical fish behaved in controlled environments. Substantial individuality still arises in clonal fishes with the same genes while being in a controlled environment. These studies from Laskowski’s team suggests that behavioral individuality “might be an inevitable and potentially unpredictable outcome of development” (Bierbach, Laskowski, and Wolf, 2017). So the argument below captures this fact, and is based on the assumption that if genes did cause psychological traits and behavior, then individuals with an identical genome would have identical psychology and behavior. But these studies show that they do not, so the conclusion follows that mind and psychological traits aren’t determined by psychology.

(P1) If the mind is determined by genetic factors, then all individuals with the same genetic makeup would exhibit identical psychological traits.
(P2) Not all individuals with the same genetic makeup exhibit identical psychological traits.
(C) Thus, mind isn’t determined by genetic factors.

I think it is a truism that an entailment of the hereditarian view would be identical genes would mean identical psychology and behavior. Quite obviously, experimental results have shown that this quite simply is not the case. If the view espoused by Rushton and Jensen and other hereditarians were true, then organisms with identical genomes would have the same behavior and psychology. But we don’t find this. Thus, we should reject hereditarianism since their claim has been tested in clonal populations and gas been found wanting.

Now how is my view not blank slatism? I deny the claim that psychology reduces to anything physical, and I deny that innate traits are a thing, so can there be nuances, or am I doomed to be labeled a blank slatist? Genetic factors are necessary pre-conditions for the mind but there are no predetermined, hardwired traits in them. While genetic factors lay the groundwork for this, the importance of learning, experience, and relevant ecological contexts must not be discounted here. While I recognize the interplay between genes and environment and other resources, I do not hold to the claim that any of them are sufficient to explain mind and psychology. I would say that Vygotsky’s theory shows how and why people and groups score differently on so-called psychological tests. There is the interplay between the child, the socio-cultural environment, and the individuals in that environment. Thus, by being in these kinds of environments, this allows the formation of mind and psychology (which is shown in cases of feral children), meaning that hereditarianism is ill-suited to explaining this with their fixation on genes, even when genes can’t explain psychology. If the mental is irreducible to the physical and genes are physical, then genes can’t explain the mental. This destroys the hereditarian argument.

Conclusion

Vygotsky’s theory provides a socio-cultural framework which acknowledges the role of subjective experiences within social contexts. Individuals engage in social interactions, and collaborative activities as conscious beings, and in doing so, they share their subjective experiences to the collective construction of knowledge and understanding. The brand of dualism I push entails that psychology doesn’t reduce to anything physical, which includes genes and the brain. But I do of course recognize the interactions between all developmental resources, I don’t think that any of them along are explanatory regarding psychology and behavior like the hereditarian, that’s one of the biggest differences between hereditarianism and the DEC. My view is similar to that of relational developmental systems theory (Lerner, 2021a, b). Further, this view is similar to Oyama’s (2002) view where she conceptualizes “nature” as a natural outcome of the organism-environment system (inline with Blumberg, 2018), and nurture as the ongoing developmental process. Thus, Oyama has reconceptualized the nature nurture debate.

Of course, my claim that psychology isn’t reducible to genes would put me in the “100% percent culture-only” camp that Rushton and Jensen articulated. However, there is no other way to be about this debate, since races are different cultural groups and different cultural groups are exposed to different cultural and psychological tools which lead to differences in knowledge and therefore lead to score differences. So I reject their dichotomy they mounted and I also reject the claim that the interactive view is effectively a “culture-only” view. But, ultimately, the argument that psychology doesn’t reduce to genes is sound, so hereditarianism is false. Furthermore, the hereditarian claim that genes cause differences in psychology and behavior is called into question due to the research on clonal populations. This shows that individuality arises randomly, and is not caused by genetic differences since there were no genetic differences.

The discussion surrounding the specific IQ debate concerning the hereditarian explanation necessitates a thorough examination of the intricate interplay between genetics and environment. A mere environmental explanation seems to be the only plausible rationale for the observed black-white IQ gap, considering that psychological states cannot be solely ascribed/reduced to genetic factors. In light of this, any attempts to dichotomize nature versus nurture, as was exemplified by Rushton and Jensen, fail to capture the essence of the matter at hand. Their reductionist approach, encapsulating a “100% culture-only program” within their 2 boxes that shows their adherence to the false dichotomy, followed by the triumphal proclamation of their seemingly preferred “50/50 split between genes and environment” explanation (although they later advocate an 80/20 perspective), can be regarded as nothing more than a fallacious oversimplification.

I have presented a comprehensive framework which challenges hereditarianism and provides an alternative perspective on the nature of human psychology and development. I integrated the principles of mind-body dualism, Vygotsky’s socio-historical theory of learning and development, and gene-environment interactions calling it Dualistic Experiential Constructivism, which acknowledges the interplay between genes, environment, and other developmental resources. Ultimately, DEC promoted a more holistic and interactive view in understanding the origin of mind through social processes and species-typical contextual-dependent events, while acknowledging genes as a necessary template for these things, since the organism is what is navigating the environment.

So this is the answer to hereditarianism—a view in which all developmental resources interact and are irreducible, in which first-personal subjective experiences with others of the species taking place in reliable ecological contexts jettison the formation of mind and psychological traits. This is called Dualistic Experiential Constructivism, and it entails a few different other frameworks that then coalesce into the view against hereditarianism that I hold.