1350 words

For years I have been arguing that hereditarianism just isn’t tenable due to the fact that the mental is irreducible to the physical. Since the mental is irreducible to the physical, then hereditarianism cannot possibly be true. I have given many conceptual arguments (here, here, here and here) which argue for (a form of) dualism, and so if dualism is true, then hereditarianism can’t possibly be true.

Here is another argument against hereditarianism:

P1: If hereditarianism is a valid science, then it must be based on a physicalist and reductionist theory of mind.
P2: The mental is irreducible to the physical.
P3: Hereditarianism is based on a physicalist and reductionist theory of mind.
C: Thus, hereditarianism is not a valid science.

Premise 1: The whole hereditarian programme assumes that psychology reduces to genes, which we can see from GWA studies of “intelligence” and other psychological traits. It’s a programme that attempts to show that differences in genes in populations lead to differences in psychological traits. However, this is merely a conceptual confusion.

Since hereditarianism attempts to reduce psychological traits to genes, then it necessarily is a physicalist and reductionist theory of mind. Hereditarianism assumes that actions and behaviors can be reduce to genes, and that we can use the methods they propose to discover these relationships. Hereditarianism, though, is said to be a scientific hypothesis and so it needs testable and falsifiable theories. But, the assumption that psychology reduces to genes is a conceptual one, and so, hereditarianism attempts to make the mind-body problem a scientific problem when it in all actuality is a conceptual argument, to which empirical evidence is irrelevant to.

Hereditarian theorists claim that standardized tests are measurement tools, and so we can then measure and quantify intelligence by administering these tests. However, there is no specified measured object, object of measurement and measurement unit for IQ (Nash, 1990), and for there to be, IQ and whatever other psychological trait the hereditarian claims to be measuring need to have those three things articulated. On another note, hereditarianism would seem to fall prey to a version of what Deacon (1990: 201) calls the numerology fallacy:

Numerology fallacies are apparent correlations that turn out to be artifacts of numerical oversimplification. Numerology fallacies in science, like their mystical counterparts, are likely to be committed when meaning is ascribed to some statistic merely by virtue of its numeric similarity to some other statistic, without supportive evidence from the empirical system that is being described.

Nonetheless, it is clear that when the hereditarian says that the mental can be measured and reduced to genes or brain structure/physiology, they are making a conceptual—not empirical—claim, and so hereditarianism would then fail on conceptual grounds. This is beside the point that (again, conceptually) that there is no a priori privileged level of causation, meaning the gene isn’t a privileged cause over and above other developmental variables (Noble, 2012) and the fact that the conceptual model of heritability and the gene used in hereditarian heritability studies is conceptually flawed (Burt and Simon, 2015). The fact of the matter is, no empirical data can refute these two arguments; these two powerful arguments then combine to refute hereditarianism, making hereditarianism logically untenable.

Hereditarianism must be a physicalist, reductionist account of the mind, and as I have argued for before, this was inevitable. Hereditarianism seeks to either reduce mind to genes or brain structure/physiology, as evidenced by for example Jung and Haier’s (2007) P-FIT model.

Premise 2: I won’t spend much time on this since I have exhaustively argued this claim. But basically, since hereditarianism relies on a physicalist and reductionist account of the mind, then mind either reduces to genes or brain structure/physiology. However, this claim fails conceptually.

Premise 3: This premise states that hereditarianism is a physicalist and reductionist theory of mind. This is evidenced by the fact that since the 80s hereditarians like Richard Haier were attempting to reduce mind (IQ, thinking) to brain physiology using EEG.

Conclusion: It then follows that hereditarianism is not a valid science. No matter how many experiments are carried out by hereditarians, this won’t prove their ideas. The ultimate claim of hereditarianism—and of mind-brain, psychophysical reduction—is a conceptual, not scientific, one.

There is also the fact that the main evidence marshaled for hereditarianism relies on heritability estimates which derive mostly from twin studies. Here’s the argument:

P1: If hereditarianism is a valid science, then it must be based on reliable and valid evidence.
P2: Hereditarianism relies mainly on heritability estimates.
P3: Heritability estimates cannot account for GxE interactions, assume additivity, and can’t account for the complex interactions between G and E.
C: Therefore, hereditarianism cannot be considered a valid science.

Science is based on observation and empirical evidence. Since the advent of twin studies, hereditarianism has relied on heritability estimates, which is a statistical measure of the variance in a trait which can be “explained” by genetic factors. Heritability estimates also assume a heterogeneous environment and that G and E don’t interact. So it then follows that if hereditarianism relies mainly on heritability estimates, then it cannot be a valid science. It doesn’t inform us what the causes of a trait or differences in them are, nor the relative influence of G and E on a trait (Moore and Shenk, 2016). There is also the fact that from these heritability estimates that they have then used and championed GWA studies to find the genes that are causal for differences in IQ scores. However, they would then need to answer the challenge in this article on PGS and I don’t see how anyone can answer it. Nevertheless, “heritability studies attempt the impossible” because “the conceptual biological model on which heritability studies depend—that of identifiably separate effects of genes vs. the environment on phenotype variance—is unsound” (Burt and Simon, 2015).

That hereditarians have shifted to brain imaging and the neurosciences (eg Kirkegaard and Fuerst, 2023) in attempting to validate hereditarianism means I can use the explanatory gap argument to put these newer claims to rest (which is basically the same as the argument I made here against the possibility of science being able to study first-personal subjective states):

P1: Mental states have a first-personal subjective aspect which cannot be captured by third-personal brain sciences.
P2: All physical states can be described in terms of their physical relations relations and properties.
C: So mental states cannot be reduced to third-personal descriptions of brain activity.

So if minds reduce to genes or brains, then we would be able to explain M in terms of P.

P1: If all mental phenomena can be fully explained in terms of physical phenomena, then there is no need for non-physical mental entities or processes.
P2: There are mental phenomena that cannot be fully explained in terms of physical phenomena.
C: Therefore, there are non-physical mental entities or processes.

If physicalism were true, then we would have no need to posit mental entities. But since there are mental phenomena that cannot be fully explained in terms of physical phenomena, then we should accept the existence of non-physical mental phenomena, which would therefore mean that dualism is true and that merely studying brain physiology and processes doesn’t mean that we are studying the mind.

Conclusion

Hereditarianism is hardly a scientific theory. It’s not a scientific theory since M doesn’t reduce to P. It’s not a scientific theory since science can’t study first-personal subjective states. The hereditarian hypothesis cannot be tested in a meaningful way—so it is therefore ad hoc. Hereditarianism should be laid to rest with other hypotheses like phlogiston. Hereditarianism makes no testable predictions. The hereditarian hypothesis is a scientific theory if and only if mind reduces to brain. But the mind doesn’t reduce to the brain. So, again, the hereditarian hypothesis isn’t a scientific theory and, therefore, the mind cannot be studied by science.

Hereditarianism should take it’s place in the annals of failed hypotheses. Hereditarians should stop claiming that hereditarianism is a scientific theory/hypothesis because it very clearly is not.