Steven Pinker: Human nature and the blank slate (1)
A year ago, I spoke to you about a book that I was just in the process of completing, that has come out in the interim, and I would like to talk to you today about some of the controversies that that book inspired.
The book is called "The Blank Slate," based on the popular idea that the human mind is a blank slate, and that all of its structure comes from socialization, culture, parenting, experience. The "blank slate" was an influential idea in the 20th century. Here are a few quotes indicating that: "Man has no nature," from the historian Jose Ortega y Gasset; "Man has no instincts," from the anthropologist Ashley Montagu; "The human brain is capable of a full range of behaviors and predisposed to none," from the late scientist Stephen Jay Gould. There are a number of reasons to doubt that the human mind is a blank slate, and some of them just come from common sense.
As many people have told me over the years, anyone who's had more than one child knows that kids come into the world with certain temperaments and talents; it doesn't all come from the outside. Oh, and anyone who has both a child and a house pet has surely noticed that the child, exposed to speech, will acquire a human language, whereas the house pet won't, presumably because of some innate different between them. And anyone who's ever been in a heterosexual relationship knows that the minds of men and the minds of women are not indistinguishable. There are also, I think, increasing results from the scientific study of humans that, indeed, we're not born blank slates. One of them, from anthropology, is the study of human universals. If you've ever taken anthropology, you know that it's a -- kind of an occupational pleasure of anthropologists to show how exotic other cultures can be, and that there are places out there where, supposedly, everything is the opposite to the way it is here. But if you instead look at what is common to the world's cultures, you find that there is an enormously rich set of behaviors and emotions and ways of construing the world that can be found in all of the world's 6,000-odd cultures. The anthropologist Donald Brown has tried to list them all, and they range from aesthetics, affection and age statuses all the way down to weaning, weapons, weather, attempts to control, the color white and a worldview. Also, genetics and neuroscience are increasingly showing that the brain is intricately structured.
This is a recent study by the neurobiologist Paul Thompson and his colleagues in which they -- using MRI -- measured the distribution of gray matter -- that is, the outer layer of the cortex -- in a large sample of pairs of people. They coded correlations in the thickness of gray matter in different parts of the brain using a false color scheme, in which no difference is coded as purple, and any color other than purple indicates a statistically significant correlation. Well, this is what happens when you pair people up at random. By definition, two people picked at random can't have correlations in the distribution of gray matter in the cortex. This is what happens in people who share half of their DNA -- fraternal twins. And as you can see, large amounts of the brain are not purple, showing that if one person has a thicker bit of cortex in that region, so does his fraternal twin. And here's what happens if you get a pair of people who share all their DNA -- namely, clones or identical twins. And you can see huge areas of cortex where there are massive correlations in the distribution of gray matter. Now, these aren't just differences in anatomy, like the shape of your ear lobes, but they have consequences in thought and behavior that are well illustrated in this famous cartoon by Charles Addams: "Separated at birth, the Mallifert twins meet accidentally.
As you can see, there are two inventors with identical contraptions in their lap, meeting in the waiting room of a patent attorney. Now, the cartoon is not such an exaggeration, because studies of identical twins who were separated at birth and then tested in adulthood show that they have astonishing similarities. And this happens in every pair of identical twins separated at birth ever studied -- but much less so with fraternal twins separated at birth. My favorite example is a pair of twins, one of whom was brought up as a Catholic in a Nazi family in Germany, the other brought up in a Jewish family in Trinidad. When they walked into the lab in Minnesota, they were wearing identical navy blue shirts with epaulettes; both of them liked to dip buttered toast in coffee, both of them kept rubber bands around their wrists, both of them flushed the toilet before using it as well as after, and both of them liked to surprise people by sneezing in crowded elevators to watch them jump. Now -- the story might seem to good to be true, but when you administer batteries of psychological tests, you get the same results -- namely, identical twins separated at birth show quite astonishing similarities. Now, given both the common sense and scientific data calling the doctrine of the blank slate into question, why should it have been such an appealing notion?
Well, there are a number of political reasons why people have found it congenial. The foremost is that if we're blank slates, then, by definition, we are equal, because zero equals zero equals zero. But if something is written on the slate, then some people could have more of it than others, and according to this line of thinking, that would justify discrimination and inequality. Another political fear of human nature is that if we are blank slates, we can perfect mankind -- the age-old dream of the perfectibility of our species through social engineering.
Whereas, if we're born with certain instincts, then perhaps some of them might condemn us to selfishness, prejudice and violence. Well, in the book, I argue that these are, in fact, non sequiturs. And just to make a long story short: first of all, the concept of fairness is not the same as the concept of sameness. And so when Thomas Jefferson wrote in the Declaration of Independence, "We hold these truths to be self-evident, that all men are created equal," he did not mean "We hold these truths to be self-evident, that all men are clones." Rather, that all men are equal in terms of their rights, and that every person ought to be treated as an individual, and not prejudged by the statistics of particular groups that they may belong to. Also, even if we were born with certain ignoble motives, they don't automatically lead to ignoble behavior. That is because the human mind is a complex system with many parts, and some of them can inhibit others. For example, there's excellent reason to believe that virtually all humans are born with a moral sense, and that we have cognitive abilities that allow us to profit from the lessons of history. So even if people did have impulses towards selfishness or greed, that's not the only thing in the skull, and there are other parts of the mind that can counteract them. In the book, I go over controversies such as this one, and a number of other hot buttons, hot zones, Chernobyls, third rails, and so on -- including the arts, cloning, crime, free will, education, evolution, gender differences, God, homosexuality, infanticide, inequality, Marxism, morality, Nazism, parenting, politics, race, rape, religion, resource depletion, social engineering, technological risk and war.
And needless to say, there were certain risks in taking on these subjects. When I wrote a first draft of the book, I circulated it to a number of colleagues for comments, and here are some of the reactions that I got: "Better get a security camera for your house." "Don't expect to get any more awards, job offers or positions in scholarly societies." "Tell your publisher not to list your hometown in your author bio." "Do you have tenure?" (Laughter) Well, the book came out in October, and nothing terrible has happened.
I -- I like -- There was indeed reason to be nervous, and there were moments in which I did feel nervous, knowing the history of what has happened to people who've taken controversial stands or discovered disquieting findings in the behavioral sciences. There are many cases, some of which I talk about in the book, of people who have been slandered, called Nazis, physically assaulted, threatened with criminal prosecution for stumbling across or arguing about controversial findings. And you never know when you're going to come across one of these booby traps. My favorite example is a pair of psychologists who did research on left-handers, and published some data showing that left-handers are, on average, more susceptible to disease, more prone to accidents and have a shorter lifespan. It's not clear, by the way, since then, whether that is an accurate generalization, but the data at the time seemed to support that. Well, pretty soon they were barraged with enraged letters, death threats, ban on the topic in a number of scientific journals, coming from irate left-handers and their advocates, and they were literally afraid to open their mail because of the venom and vituperation that they had inadvertently inspired. Well, the night is young, but the book has been out for half a year, and nothing terrible has happened.
None of the dire professional consequences has taken place -- I haven't been exiled from the city of Cambridge. But what I wanted to talk about are two of these hot buttons that have aroused the strongest response in the 80-odd reviews that The Blank Slate has received. I'll just put that list up for a few seconds, and see if you can guess which two -- I would estimate that probably two of these topics inspired probably 90 percent of the reaction in the various reviews and radio interviews. It's not violence and war, it's not race, it's not gender, it's not Marxism, it's not Nazism. They are: the arts and parenting. (Laughter) So let me tell you what aroused such irate responses, and I'll let you decide if whether they -- the claims are really that outrageous.