The Language Instinct: How the Mind Creates Language (72 page)

What kind of psychology underlies this talent? How does our mental similarity space accord with this part of the cosmos? Plants and animals are special kinds of objects. For a mind to reason intelligently about them, it should treat them differently from rocks, islands, clouds, tools, machines, and money, among other things. Here are four of the basic differences. First, organisms (at least, sexual organisms) belong to populations of interbreeding individuals adapted to an ecological niche; this makes them fall into species with a relatively unified structure and behavior. For example, all robins are more or less alike, but they are different from sparrows. Second, related species descended from a common ancestor by splitting off from a lineage; this makes them fall into non-overlapping, hierarchically included classes. For example, sparrows and robins are alike in being birds, birds and mammals are alike in being vertebrates, vertebrates and insects are alike in being animals. Third, because an organism is a complex, self-preserving system, it is governed by dynamic physiological processes that are lawful even when hidden. For example, the biochemical organization of an organism enables it to grow and move, and is lost when it dies. Fourth, because organisms have separate genotypes and phenotypes, they have a hidden “essence” that is conserved as they grow, change form, and reproduce. For example, a caterpillar, chrysalis, and butterfly are in a crucial sense the same animal.

Remarkably, people’s unschooled intuition about living things seems to mesh with these core biological facts, including the intuitions of young children who cannot read and have not set foot in a biology lab.

The anthropologists Brent Berlin and Scott Atran have studied folk taxonomies of flora and fauna. They have found that, universally, people group local plants and animals into kinds that correspond to the
genus
level in the Linnaean classification system of professional biology (species-genus-family-order-class-phylum-kingdom). Since most locales contain a single species from any genus, these folk categories usually correspond to species as well. People also classify kinds into higher-level life-forms, like tree, grass, moss, quadruped, bird, fish, and insect. Most of the life-form categories of animals coincide with the biologist’s level of
class
. Folk classifications, like professional biologist’s classifications, are strictly hierarchical: every plant or animal belongs to one and only one genus; every genus belongs to only one life-form; every life-form is either a plant or an animal; plants and animals are living things, and every object is either a living thing or not. All this gives people’s intuitive biological concepts a logical structure that is different from the one that organizes their other concepts, such as human-made artifacts. Whereas people everywhere say that an animal cannot be both fish and fowl, they are perfectly happy with saying, for example, that a wheelchair can be both furniture and vehicle, or that a piano can be both musical instrument and furniture. And this in turn makes reasoning about natural kinds different from reasoning about artifacts. People can deduce that if a trout is a kind offish and a fish is a kind of animal, then a trout is a kind of animal. But they do not infer that if a car seat is a kind of chair and a chair is a kind of furniture, then a car seat is a kind of furniture.

Special intuitions about living things begin early in life. Recall that the human infant is far from being a bag of reflexes, mewling and puking in the nurse’s arms. Three- to six-month infants, well before they can move about or even see very well, know about objects and their possible motions, how they causally impinge on one another, their properties like compressibility, and their number and how it changes with addition and subtraction. The distinction between living and nonliving things is appreciated early, perhaps before the first birthday. The cut initially takes the form of a difference between inanimate objects that move around according to the laws of billiard-ball physics and objects like people and animals that are self-propelled. For example, in an experiment by the psychologist Elizabeth Spelke, a baby is shown a ball rolling behind a screen and another ball emerging from the other side, over and over again to the point of boredom. If the screen is removed and the infant sees the expected hidden event, one ball hitting the other and launching it on its way, the baby’s interest is only momentarily revived; presumably this is what the baby had been imagining all along. But if the screen is removed and the baby sees the magical event of one object stopping dead in its tracks without reaching the second ball, and the second ball taking off mysteriously on its own, the baby stares for much longer. Crucially, infants expect inanimate balls and animate people to move according to different laws. In another scenario, people, not balls, disappeared and appeared from behind the screen. After the screen was removed, the infants showed little surprise when they saw one person stop short and the other up and move; they were more surprised by a collision.

By the time children are of nursery school and kindergarten age, they display a subtle understanding that living things fall into kinds with hidden essences. The psychologist Frank Keil has challenged children with pixilated questions like these:

For artifacts like a coffeepot turning into a bird feeder (or a deck of cards turning into toilet paper), the children accepted the changes at face value: a birdfeeder is anything that is meant to feed birds, so that thing is a birdfeeder. But for natural kinds like a raccoon turning into a skunk (or a grapefruit turning into an orange), they were more resistant; there was some invisible raccoonhood lingering in the skunk’s clothing, and they were less likely to say that the new creature was a skunk. And for violations of the boundary between artifacts and natural kinds, like a toy turning into a bird (or a porcupine turning into a hairbrush), they were adamant: a bird is a bird and a toy is a toy. Keil also showed that children are uncomfortable with the idea of a horse that has cow insides and cow parents and cow babies, even though they have no problem with a key that is made of melted-down pennies and is then melted down to make pennies again.

And of course adults from other cultures have the same sorts of intuitions. Illiterate rural Nigerians were given the following kind of question:

A typical response was, “It’s a pawpaw, because a pawpaw has its own structure from heaven and a pineapple its own origin. One cannot turn into the other.”

Little children also sense that animal kinds fall into larger categories, and their generalizations follow the similarity defined by category membership, not mere similarity of appearance. Susan Gelman and Ellen Markman showed three-year-old children a picture of a flamingo, a picture of a bat, and a picture of a blackbird, which looked a lot more like the bat than like the flamingo. They told the kids that a flamingo feeds its babies mashed-up food but a bat feeds its babies milk, and asked them what the blackbird feeds its babies. With no further information, children went by appearances and predicted milk. But all it took was a mention that flamingos and blackbirds were birds, and the children lumped them together and predicted mashed-up food.

And if you really doubt that we have botany instincts, consider one of the oddest of human motives: looking at flowers. A huge industry specializes in breeding and growing flowers for people to use in decorating dwellings and parks. Some research shows that bringing flowers to hospital patients is more than a warm gesture; it may actually improve the patient’s mood and recovery rate. Since people rarely eat flowers, this diversion of effort and resources seems inexplicably frivolous. But if we evolved as intuitive botanists, it makes some sense. A flower is a microfiche of botanical information. When plants are not in bloom, they blend into a sea of green. A flower is often the only way to identify a plant species, even for a professional taxonomist. Flowers also signal seasons and terrains of expected bounty and the exact locations of future fruits and seeds. A motive to pay attention to flowers, and to be where they are, would obviously have been useful in environments where there were no year-round salad bars.

Intuitive biology is, of course, very different from what professors of biology do in their laboratories. But professional biology may have intuitive biology at its foundation. Folk taxonomy was obviously the predecessor to Linnaean taxonomy, and even today, professional taxonomists rarely contradict indigenous tribes when they classify the local species. The intuitive conviction that living things have a hidden essence and are governed by hidden processes is clearly what impelled the first professional biologists to try to understand the nature of plants and animals by bringing them into the laboratory and putting bits of them under a microscope. Anyone who announced he was trying to understand the nature of chairs by bringing them into a laboratory and putting bits of them under a microscope would surely be dismissed as mad, not given a grant. Indeed, probably all of science and mathematics is driven by intuitions coming from innate modules like number, mechanics, mental maps, even law. Physical analogies (heat is a fluid, electrons are particles), visual metaphors (linear function, rectangular matrix), and social and legal terminology (attraction, obeying laws) are used throughout science. And if you will allow me to sneak in one more offhand remark that really deserves a book of its own, I would guess that most other human “cultural” practices (competitive sports, narrative literature, landscape design, ballet), no matter how much they seem like arbitrary outcomes of a Borgesian lottery, are clever technologies we have invented to exercise and stimulate mental modules that were originally designed for specific adaptive functions.

So the language instinct suggests a mind of adapted computational modules rather than the blank slate, lump of wax, or general-purpose computer of the Standard Social Science Model. But what does this view say about the secular ideology of equality and opportunity that the model has provided us? If we abandon the SSSM, are we forced to repugnant doctrines like “biological determinism”?

Let me begin with what I hope are obvious points. First, the human brain works however it works. Wishing for it to work in some way as a shortcut to justifying some ethical principle undermines both the science and the ethics (for what happens to the principle if the scientific facts turn out to go the other way?). Second, there is no foreseeable discovery in psychology that could bear on the self-evident truth that ethically and politically, all people are created equal, that they are endowed with certain inalienable rights, and that among these are life, liberty, and the pursuit of happiness. Finally, radical empiricism is not necessarily a progressive, humanitarian doctrine. A blank slate is a dictator’s dream. Some psychology textbooks mention the “fact” that Spartan and samurai mothers smiled upon hearing that their sons fell in battle. Since history is written by generals, not mothers, we can dismiss this incredible claim, but it is clear what purposes it must have served.

With those points out of the way, I do want to point out some implications of the theory of cognitive instincts for heredity and humankind, for they are the opposite of what many people expect. It is a shame that the following two claims are so often confused:

The two claims could not be more different. Take number of legs. The reason that some people have fewer legs than others is 100% due to the environment. The reason that all uninjured people have exactly two legs (rather than eight, or six, or none) is 100% due to heredity. But claims that a universal human nature is innate are often run together with claims that differences between individuals, sexes, or races are innate. One can see the misguided motive for running them together: if
nothing
in the mind is innate, then differences between people’s minds cannot be innate; thus it would be good if the mind had no structure because then decent egalitarians would have nothing to worry about. But the logical inverse is false. Everyone could be born with identical, richly structured minds, and all differences among them could be bits of acquired knowledge and minor perturbations that accumulate through people’s history of life experiences. So even for people who, inadvisably in my view, like to conflate science and ethics, there is no need for alarm at the search for innate mental structure, whatever the truth turns out to be.