The myth of the well-filled slate: we shouldn’t discount the influence of society on our lives Carlos Orsi The Skeptic

Twenty years ago, Steven Pinker published the bestseller “The Blank Slate” (2002) in which he argued that important sectors of the social sciences, psychology and political philosophy were making the mistake of insisting on a false and outdated model of human nature. According to this blank slate model, each human individual would be like a clean blackboard at birth, where the chalk of education, society, and culture could write anything — an infinitely malleable mass, whose only significant genetic inheritance would be that of belonging to the Homo sapiens species.

Perhaps the clearest articulation of the blank slate model came from the American psychologist John B. Watson (1878-1958) in 1924. Watson, founder of behaviourism, wrote the following (precisely, in a book entitled “Behaviorism”):

Give me a dozen well-formed, healthy infants, and my own specified world to bring them up in, and I’ll guarantee to take any one at random and train him to become any type of specialist I might select — doctor, lawyer, artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations…

By combining Watson’s behaviourist radicalism with the hypothesis developed by anthropologist Franz Boas (1858-1942) — that the differences between human groups can be explained by their historical background and cultural habits, and not by some kind of ethnic “essence” — one arrives at the formulation that culture and education would be virtually omnipotent in the construction of human phenomena. By transforming education, the individual would be transformed. By transforming culture, humanity would be transformed, and the possibilities would be endless.

This is the blank slate model, which Pinker denounces as a kind of politically correct orthodoxy in the humanities, a well-meaning obscurantism that leads the “humanities guys” to ignore the theory of evolution, and to react with irrational horror to the mere mention of a biological hypothesis to account for a psychological or social phenomenon. Evidently, this idea — that human beings and their behavior are infinitely malleable, and that the only biological impositions we must submit to at birth are those that, for example, prevent us from flying or breathing underwater — is wrong, and has already caused great social and individual harm.

Pinker cites the case of a boy who suffered penile mutilation as a baby, and whose parents were instructed by their pediatrician to raise him as a girl. For many years, this story was presented as proof that gender is a product of socialisation, but only until a scientific article published in 1997 showed that the girl “Joan” had not only spent a good part of her life loathing the female identity imposed on her — to the point of rejecting the hormone treatment recommended for her at the onset of puberty — but had also completely reverted to her original masculine identity of “John” at the age of 16.


One of the truest things about science is that all scientific models are wrong, but some are useful. Furthermore, their usefulness is only valid for very well-defined applications. A map depicting the Earth’s surface as flat is wrong, but it can be useful when traveling from São Paulo to Campinas.

The blank slate model, particularly as it was synthesised in the 1920s-30s, emerged at a historical moment when the alternative model was one of absolute biological determinism. In his masterful book entitled “The Myth of Race,” anthropologist Robert W. Sussman (1941-2016) explains that rediscovery of the work conducted by Gregor Mendel (1822-1884) on heredity, and the experimental finding that there was no genetic inheritance of acquired characteristics (e.g. children of muscular parents were not born stronger) led many scientists and intellectuals, mainly in the US, England, and Germany, to postulate that all behavioural and personality traits were hereditary and transmitted by simple Mendelian inheritance.

Culture would be a fixed characteristic of ethnicity, a collective phenotype, and education would be powerless in converting “savages” into “civilized people.” In other words, everything — even something like “thalassophilia” (a knack for maritime life), which presumably made good Navy officers — would be passed down from parent to child, according to the binary rules of dominant and recessive genes, those same rules that today’s students are required to know for their biology tests.

Compared to this alternative, the blank slate is an excellent model. Boas’s historical and cultural relativism, in particular, has proven to be much more successful empirically than Mendelian genetic determinism, in that it describes and explains reality far better. If we are to rely on oversimplification, the “everything is culture” idea provides a much more sophisticated and reliable map of the territory being explored than the “everything is genes” idea.


Even if a map is better than the alternatives available at a given historical moment, it can be corrected and improved later on. Pinker argues that the orthodoxy of the humanities has refused to update its map of social and psychological phenomena with the scientific facts that attest to the influence wrought by genetics and evolution on these phenomena, for eminently political reasons (namely, a commitment to the ideal of equality).

Undeniably, there’s still some resistance to incorporating biological considerations into the humanities, particularly in the areas more connected to public policy-making (e.g. policies for combating racial and gender discrimination), but it would be a caricature to attribute all of this resistance to mere political prejudice or unyielding leftism. There are a couple of good rational reasons for this. The first is the problem of the explanatory level. The second is the effect size.

The explanatory level refers to how far down the architecture of science one needs to go to find an adequate explanation for a given phenomenon. Societies are made up of human beings, in other words, biological entities who function based on chemical reactions governed by the laws of physics. From that perspective, it should be possible to use quantum physics to explain the start of World War I, but exactly what purpose would this explanation serve? Who would be capable of comprehending it? What would be its relevance?

Clearly, a “higher” science in the edifice of explanatory levels could never contradict a more fundamental result: the roof cannot stand without the foundations, and a sociological hypothesis that contradicted the Theory of Relativity would be stillborn. However, whether or not one should cite the foundation — rather than imply it — to describe the ceiling, only the particularities of each case can say, and this “case-to case judgement” will depend on the effect size. In other words, we would have to ask: can a phenomenon be explained based on the considerations of a more fundamental level? And, if so, would the explanation be at all helpful? When it comes to psychological or social differences, the answers seem to be ‘it depends,’ and ‘very little,’ respectively.

Most of the time, keeping biology as a silent backdrop when attempting to explain complex social phenomena is as reasonable as not considering subatomic interactions when trying to explain the outcome of the World Cup, and, for that matter, is just as devoid of any “obscurantism” or “ideological motivation.”

Well-filled slate

On publication, “The Blank Slate” prompted a series of criticisms towards anti-discriminatory public policies as being counterproductive because they would be unnatural — the sociopolitical equivalent of Watson’s crass behaviourism. If read carefully, Pinker’s book is more nuanced and subtle than that. However, a rushed reading of it has become a banner for conservatives who consider that Western society is the finish line of civilizing development, and that, not only is there nothing more to improve, but it is time to go back a few centuries. This is the well-filled slate crowd.

For instance, by stating that the professional preferences of men and women are different, because there are innate differences in personality, and that this is reason enough to adequately justify the disparities between the sexes — even better than the discrimination hypothesis — with respect to access to certain careers and income levels, Pinker bites off more than he can chew, and provides munition to those advocating the well-filled slate.

The misconception is not as gross as the one implied in saying that “being a ship’s captain is a Mendelian characteristic,” but it comes close. The fact that average differences in personality exist does not necessarily mean that they are innate — hence not produced culturally — or that they are relevant to all cases where discrimination is suspected, or even that their effects in today’s society are consistently greater than those of discrimination. 

Pinker gives special emphasis to opinion polls on work and career choices, where, in his words, “men and women say what they want.” However, he apparently fails to take into account the psychological question of desirability, i.e. the tendency of interviewees to respond to surveys according to what they imagine the interviewer expects or would like to hear, an issue that particularly affects surveys involving stereotypes and social roles. “Men, on average, are more willing to face physical discomfort and danger,” he writes. Are they really? Or do they just say they are, knowing that this is what is expected of a “real” man?

Then there’s the problem of generalisation, which hides behind the expression “on average.” The book “Brain Gender,” by neuroscientist Melissa Hines, discusses data from studies investigating the average differences between men and women in terms of standard deviations, as a means of assessing how much one population mean is different from another (technically, the author talks about a statistic called “Cohen’s d”, but we’ll skip the details).

The sexual orientation of men and women differs by six standard deviations: a very substantial majority of men say they prefer having sex with women over men, and vice versa. Height differs by two standard deviations: most men are noticeably taller than most women. In contrast, two cognitive and behavioural traits — mathematical prowess and physical aggressiveness — differ by less than half a standard deviation.

In an interview given to journalist Angela Saini (published in the book “Inferior”), Hines further adds that the difference between sexes in terms of the ability to empathise (which, according to the well-filled slate model, would explain why there are so many more female nurses than female engineers) is also about half a standard deviation. In an article published in 2005 by psychologist Janet Shibley, Hyde summarised the results of more than 40 studies on the differences in personality between the sexes, most of which were well below one standard deviation; a large number of these differences were in the second decimal place (0.07), including those regarding negotiation competitiveness.

Compared to these modest effects, the historical impact of discrimination takes on colossal proportions. In Brazil, there was only one woman trained in medicine in the entire country in the 1830s. In comparison, the first medical degree awarded to a woman in the US occurred in 1847. In 1910, female doctors accounted for 22% of medical professionals in Brazil. A hundred years later, this figure rose to 40%, and, in 2020, to 47%. It seems unlikely that the jump from a single female doctor in 1834 to nearly 223,000 in 2020 was caused by a change in hereditary, innate preferences, or in the effects of oestrogen on the central nervous system of the fetus.

The Polytechnic School of São Paulo, today part of the University of São Paulo (USP), was founded in 1893, and had only two female audit students (hence not actually enrolled) between the opening date and the 1920s. Only in 1928 would the first female engineer graduate there. Currently, 56 (13%) of the institution’s 415 professors are women. Of the 1,588 graduate students (master’s and doctoral), 417 (26%) are women.

Recognising that there are biological factors linked to personality, talents, and preferences does not mean that we have to accept these factors as the predominant cause of our current social arrangement, or that any deliberate sociopolitical effort to reduce glaring inequalities is a mistake or the result of ideological inflexibility. The evidence to this effect is far more precarious than what the well-filled slate upholders like to go around trumpeting about.

In view of historical experience, well-filled slate advocates make two seemingly extraordinary claims. The first is that social asymmetries — which suggest prima facie that there is unfair discrimination or cultural bias in place  — reflect some sort of biological “point of equilibrium.” The second is that the precise nature of human differences observed in Western societies has not only been unravelled, but is predominantly innate. As we all know, extraordinary claims require extraordinary evidence. And theirs is flimsy at best.

This article was translated from the original Portuguese by Ricardo Borges Costa.

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Twenty years after Steven Pinker’s “The Blank Slate”, we should be wary of those who make claims about innate traits that separate nature from nurture
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