The sophistication of these systems in infants resembles that of modules in nonhuman primates, suggesting an ancient, evolutionary development; a six-month-old baby understands numbers, space, objects and faces much as a mature rhesus monkey does. As Spelke sees it, these cognitive tools underlie all the more complex skills and knowledge we master as we grow up--spoken languages, number manipulation and other abstract mental operations. Core knowledge forms the basis for the robust cognitive machinery that gets us through life. And we almost completely ignore it.
"Even for adults," Spelke says, "most of what we know that lets us negotiate the world, guide our choice of paths through the environment, understand whether a car down the street might hit us or whether a falling object will miss us, even what we say as we're conversing--most of that is completely unconscious. How many things do we do that we hardly think about? Most of what we do is like that. We operate on richly structured cognitive systems that aren't usually accessible to introspection. To me, this is one more sign that most of our cognitive workings are much like those of babies and are built on the core knowledge that we had as babies."
Equality of the Sexes
This view of Spelke's is what philosophers call a "nativist" theory--that certain of our traits are inborn. They are natural rather than nurtured. Spelke knows well that this puts her on a slippery slope. To speak of native abilities is to court speculation about native differences in those abilities. In early 2005 Spelke found herself involved in a hot controversy about such possible differences when she was repeatedly asked for her opinion of Harvard president Lawrence Summers's remarks, made that January, that biological disparities might help explain why women occupy so few places in university math and science departments. Spelke, of course, was the natural choice to debate this topic, not only because she was a prominent, highly accomplished scientist at Summers's university but because she got there by studying precisely the innate abilities Summers wondered about. Although she hardly seems a scrapper by inclination, Spelke is quick-witted, funny, impressively well informed and eminently agile in conversation. And she rose quite gracefully to the task of popping Summers's thought balloon.
"If you look at things Summers's way," she says in her office, leaning forward in her chair with a sly grin, "then to study innate cognitive abilities, like I do, is supposedly to study gender differences. In fact, I didn't know we were studying gender differences at all, because we don't find any. But since the subject came up"--she spread her hands, clasped them, then sat back in her chair, smiling--"I was happy to tell him about our work."
Summers got an earful, if not directly, as Spelke described in several interviews and in a high-profile public debate with her colleague and friend Harvard psychologist Steven Pinker how voluminous evidence from decades of research shows little if any inherently sex-based differences in infants or toddlers. At those early ages, when culture has the least effect but sex hormone levels are extremely high, no sex-based differences have shown themselves in a huge variety of skills that underlie mathematical thinking. For example: put a four-year-old in a distinctly shaped room, hide a block in a corner, have the four-year-old close his eyes and spin around, then have the child hunt for the block. Some of the children will quickly reorient themselves in the room and find the object, whereas others will not. Yet the percentages of boys and girls who succeed are identical. So although "there is a biological foundation to mathematical and scientific reasoning," as Spelke put it in her debate with Pinker, "these systems develop equally in males and females."
Spelke, an unabashed optimist, believes our growing understanding of cognitive abilities will eventually reduce, rather than inspire, divisions about our human qualities. "This idea that we have native abilities," she tells me, "some find threatening, for it seems to invite the idea that some types of people might be innately better endowed than others. If you're a nativist about basic core cognitive capacities, as I am, does that also lead you to be a nativist about, say, differences among the sexes? These claims of biological bases can proliferate to a point where they end up being invoked to explain everything. But you have to be very careful about what data you use." The information that seems to indicate sex differences, Spelke says, comes from problematic studies whose results are colored by cultural influences--everything from parents responding differently to girls and boys to university faculties viewing identical job applications more skeptically when the applicant's name is female. Summers must have taken that last point to heart: in May 2005 he announced that Harvard would spend 50 million over 10 years to recruit and support women and minorities on its faculty.