Interesting book review on human nature

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Posted by Lilly from ? ( on Thursday, September 19, 2002 at 2:15PM :

Nature 419, 251 - 252 (19 September 2002);

Nurturing a view of human nature


David Hull is in the Department of Philosophy, Northwestern University, Evanston, Illinois 60208-1315, USA.

Our genes ensure that our minds are never 'blank slates'.

The Blank Slate: The Modern Denial of Human Nature
by Steven Pinker
Allen Lane (Penguin)/Viking: 2002. 561 pp. ú25/$27.95

Steven Pinker begins the preface of his book with the exclamation: "Not another book on nature and nurture!" In fact, the contrast between nature and nurture is only one of the topics that Pinker addresses in this book, but throughout his exposition I shared the dismay of his hypothetical reader. Few people nowadays who know anything about genetics, evolution and development can maintain that the human mind is a blank slate. Every phenotypic trait exhibited by living creatures is the result of a complex interplay between nature and nurture, genes and environment. No characteristic is entirely innate or strictly acquired. Even the seventeenth-century philosopher John Locke, who coined the phrase tabula rasa or 'clean slate', acknowledged that the mind has "innate capacities". With respect to minds being blank slates at birth, surely Pinker is beating a straw man with a dead horse.

In most of his book, Pinker accepts the natureľnurture distinction and complains that his opponents do not give nature sufficient weight, but towards the end he stumbles on quite a different conclusion. Perhaps the natureľnurture distinction itself is at fault. Pinker acknowledges that the human genome cannot possibly specify every connection among our neurons. The environment, in the sense of "information encoded by the sense organs", also plays a role, but even these two causal factors are not enough. Chance also contributes to development: for example, one twin lies one way in the womb, the other lies a different way. The non-genetic component of personality may well be to some extent the outcome of "neurodevelopmental roulette", as Pinker puts it. "Just as the 'genetic' term in the behavioural geneticist's equation is not necessarily genetic, the 'environmental' term is not necessarily environmental," he explains. In short, distinguishing between genes and environment may not be a very perspicuous way of dividing up the developmental pie. Support for this conclusion comes from the difficulty of saying anything both clear and straightforward using this distinction.

Pinker called his book The Blank Slate. He thinks that lots of people believe that we are born with minds that are totally blank; I do not think that this view is so widely accepted. The book's subtitle is The Modern Denial of Human Nature, and here again I disagree with him about how widely distributed this rejection is. Pinker thinks that a large proportion of the reading public denies the existence of human nature. I have taught philosophy to hundreds of undergraduates over the years, and they all claim to believe in human nature. They disagree widely on what this nature is, but like Pinker they take for granted that it exists. All humans, and only humans, exhibit a particular characteristic. Anyone who lacks this characteristic is abnormal, not truly human.

From the perspective of embryological development, labelling certain traits and genes 'abnormal' makes some sense. Certain alleles perform a particular function better than other alleles. For example, those people who suffer from sickle-cell anaemia possess an abnormal gene. So do those of us with blue eyes. Both traits are due to damaged genes. It may be appropriate to consider certain traits and genes as being abnormal from the perspective of embryological development, but it makes no sense with respect to evolution. Every gene that we now possess was once unique. Natural selection is the primary mechanism for changing gene frequencies. As a gene decreases in frequency, it does not become increasingly abnormal.

Pinker terms himself an evolutionary psychologist, but one of the requirements of evolution by means of natural selection is variation, both genotypic and phenotypic. Variation is the essence of selection, and Pinker knows it. He estimates that roughly half of the variation in traits is due to genetic variation, and that half of the human genome that functions in development is involved in producing the human brain. Yet, at the level of human minds, none of this variation matters. Way down deep, all minds are essentially the same.

Of course, the easy response is that all this variability can be dismissed as abnormal. Pinker says that his book is primarily about human nature Ś an endowment that is universal in 'healthy' members of Homo sapiens. In an appendix he presents Donald Brown's list of almost 400 human universals, one of them being to distinguish between normal and abnormal states. But Pinker admits that many of these traits are universal only among 'normal' people or in 'normal' circumstances. However, as much as these superficial universals vary, at a deeper level he thinks that there are truly universal universals; that beneath superficial differences, our species has a "psychological unity".

What puzzles me is why Pinker adopts as one of the essential tenets of evolutionary psychology a position that runs so counter to evolutionary theory. Why have evolutionary psychologists saddled themselves with the monomorphic mind? We do not have monomorphic blood types, monomorphic eye colour, or monomorphic hearts. So why are evolutionary psychologists so insistent that we all have monomorphic minds? One possible answer is to avoid the charge of racism.

Those people, whoever they may be, who actually believe that all minds are blank slates are off the hook with respect to being called racists; after all, blank is blank. But evolutionary psychologists insist that genes play an important role in making us what we are, and it is possible that these genes cluster. Some subgroup of human beings might have more of the 'good' genes than other subgroups. As a result, a charge of racism might have some justification. But if all the variation that occurs among people is only surface variation, then evolutionary psychologists are also off the hook: we all have fundamentally the same mind. Those evolutionary biologists who think that both genes and traits are distributed in highly complex ways can also avoid being termed racists, but their argument is a good deal more complex.

Much of this discussion presupposes that in order to have the same rights, we must all be fundamentally the same. Pinker argues that, at a very fundamental level, all human beings are the same. Hence, we all have the same rights. But he also quotes Ernst Mayr as arguing for a much more sophisticated position: that equality does not require identity. Why can't we all have the same rights even if in many ways we are essentially different? That is the question.

I oppose the blank-slate view of human minds as strongly as Pinker does. I just do not think that it is as widespread as he does. I also think, contrary to Pinker, that a belief in the existence of something properly termed 'human nature' is very widespread. The trouble is that these 'natures' are highly variable, as indeed they must be if they are to evolve. They are innate but neither fixed nor universal. In The Blank Slate, Pinker presents an overarching view of the world in a way that quite a few readers will find seductive. The preceding objections aside, I find myself in basic agreement with Pinker's world-view. That I can accept so much of what he has to say while rejecting one of the positions that he takes to be fundamental implies that possibly this position is not really so fundamental.

-- Lilly
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