Many of us would like to believe that we play a big role in the development of our children's personalities. But science tells us that other factors, such as genetics, culture and chance brain events, have a greater impact than parents, argued Massachusetts Institute of Technology psychologist and author Steven Pinker, PhD, at APA's 2002 Annual Convention in Chicago.
Our gut instinct can be to hotly contest such findings, said Pinker, because they appear to conflict with the moral values that many of us tie to beliefs about human nature.
For example, if parents can't shape their children's personalities, does that mean it's not important to treat them well? Of course not, Pinker argued. After all, even though parents don't determine their children's personas, how they treat their children has a big influence on children's happiness and the quality of the parent-child relationship.
Drawing from his latest book, "The Blank Slate: The Modern Denial of Human Nature" (Viking Press, 2002), Pinker discussed common theories about human nature and why he believes modern science's understanding of the brain and behavior seems to conflict with them:
The Blank Slate. John Locke's idea that the mind begins as a blank sheet of paper that's filled with our experiences as we age appeals to us because it seems to imply that we're all created equal, said Pinker. The problem with the Blank Slate, he argued, is that environment isn't everything.
"No one denies the importance of learning, socialization, and the creation and transmission of culture. The question is, how do they work?" he explained. "You need some kind of innate machinery to accomplish learning and socialization, and the creation and transmission of culture."
As evidence of the significant role of genetics in brain development, Pinker pointed to studies of identical twins that have found that the distribution of gray matter in their cortexes, including the areas underlying language and general intelligence, are highly similar.
In addition, researchers have shown that diverse cultures share myriad behavioral properties, from aesthetics, affection and anthropomorphization to verbs, violence and vowel contrasts-- properties Pinker said are evidence of the significant role of genetics in behavior.
The Noble Savage. Rousseau's idea that primitive man is morally superior to civilized man also has its attractions, Pinker said. "We see it in the respect for all things natural and the distrust for things man-made: natural child birth, natural medicines, natural yogurt, and so on," he said.
However, anthropologists have called into question the Noble Savage doctrine, Pinker said, by documenting the ubiquity of conflict in both modern and "natural state" societies, such as groups in the Amazon rain forest and New Guinea. Moreover, researchers have evidence of some degree of the heritability of negative traits such as aggression.
But the fear of some, said Pinker, is that if unpleasant traits are innate, that would mean that they're unchangeable and, therefore, that social improvement efforts are futile.
He countered by arguing that even though some brain systems may predispose us toward aggression, other parts of the brain, such as what are referred to as its frontal lobe executive systems, can help inhibit that disposition. For example, he recounted research that has found that up to 80 percent of men and 60 percent of women have thought about killing someone, but far fewer carry through with the act.
The Ghost in the Machine. Rene Descartes's idea that the mind is separate from the body appeals to people because it gives hope that we have free will and that the mind can survive the death of the body, Pinker claimed. He pointed to data from neuroscience that he argued demonstrate that the mind and body are not separate entities: "We know that by sending an electrical current to the brain, you can have a life-like experience, that the chemical environment of the brain can radically affect emotion and perception and experience."
Moreover, Pinker argued that he believes that "when the brain dies, the person goes out of existence," adding that "many people believe in [an afterlife], but I don't think it's a terribly good argument. For one thing, belief in a life to come devalues life on earth."
When scientists talk about the human mind as a machine and not a soul, he said, some interpret that to mean that concepts such as love, beauty and morality are just figments of a brain pursuing selfish evolutionary strategies.
"The idea that we have metaphorically selfish genes or [that] the process of evolution has no purpose and is amoral doesn't mean that we are selfish or that we don't have any purpose," he said. "There's nothing that prevented the amoral process of evolution from endowing us with a sense of morality, and beauty and of love, and all of the other things that make life worth living."