Born in the Tower of Babble : THE LANGUAGE INSTINCT: How the Mind Creates Language, <i> By Steven Pinker (William Morrow: $23; 494 pp.)</i> : PATTERNS IN THE MIND: Language and Human Nature, <i> By Ray Jackendoff (Basic Books: $25; 239 pp.)</i>

Two years ago, a newspaper report from a scientific meeting read, “Ability to Learn Grammar Laid to Gene by Researcher.” To psychologists and linguists, the notion that grammatical rules might be the inflexible products of strings of DNA molecules, rather than having been shaped by the nuances of a cultural milieu, was stunning, not to say heretical. To the syndicated columnist Erma Bombeck, however, it all made perfect sense.

Bombeck’s husband once taught English in high school. “He had 37 grammar-gene deficients in his class at one time,” she informed her readers. To them, she explained, “a comma could have been a petroglyph. A subjective complement was something you said to a friend when her hair came out right. A dangling participle was not their problem.” And yet, Bombeck speculated, each and every one of these kids finished up as major sports figures, rock stars and television personalities, “who make millions spewing out words such as bummer, radical and awesome and thinking they are complete sentences.”

Bombeck’s observations aside, one of the great mysteries of human life is the fact that children learn language (not just words, but complicated grammatical structure) with amazing facility--yeah, like, I mean, really! In his “Patterns in the Mind,” Ray Jackendoff refers to this as the Paradox of Language Acquisition. If linguists are so smart, how come they’re so dumb that they can’t do what kids of two can do while chucking food around the room and sticking their fingers into electrical outlets? That is, figure out the principles behind the grammatical patterns of various languages.

The nature of language has long fascinated scholars. Obsessed would be a more accurate description. And perhaps it’s not surprising that scholars whose stock in trade is words should be able to employ them with such stinging effect against their academic adversaries: They do so at every opportunity.

There is a huge intellectual divide across which their carefully hewn invectives are hurled with such enthusiasm. On one side, there are those who believe that language acquisition is an innate process, which is fine tuned by the environment in early infancy. On the other side, children are viewed as acquiring language solely through learning, through attentive imitation of Motherese and other voices they hear in the babble about them.

The most prominent proponent of language as an innate phenomenon is Noam Chomsky, a linguist at the Massachusetts Institute of Technology (MIT). When, in 1957, Chomsky published his landmark book “Syntactic Structures,” he challenged the prevailing wisdom of psychology--namely, behaviorism. According to the behaviorists, nothing existed in the brain that hadn’t been put there through experience. In other words, we come into the world with a mental blank slate.

One of Chomsky’s strongest arguments was the Paradox of Language Acquisition. Normal learning patterns surely could not explain the phenomenon. Children must therefore be innately equipped with an understanding of grammar. Chomsky called this a Universal Grammar.

Chomsky’s view became dominant, forcing linguists to focus on syntax as the central feature of language acquisition--for a while. Amid mini-rebellions among Chomsky’s acolytes, those who favor language as a learned behavior have recently made a comeback, although not in the strict behaviorist mold. Steven Pinker’s “The Language Instinct” and Jackendoff’s “Patterns of the Mind” represent blasts from the innatists’ side of the divide.

Both authors present evidence in favor of a strong genetic basis for the learning of language. And both view language as just one of many behaviors that are generated by genetically determined modules within the brain. Both books are therefore provocative, not only in their uncompromising promotion of the innatists’ program in linguistics, but also in extending this paradigm to other realms of human behavior.

Jackendoff and Pinker proffer similar evidence and weave similar arguments in making the case for the Genetic Hypothesis of language. But their approach as authors is different. “My goal is to offer the reader a few evenings of engagement with the ideas of linguistics, without a great investment in technical detail,” Jackendoff says. “For better or worse,” Pinker concedes, “I can write in only one way, with a passion for powerful, explanatory ideas and a torrent of relevant detail.” Both authors are true to their word, and each book is splendid in its own way. It is therefore up to potential buyers to select the amount of detail for which they have appetites.

Much of the evidence presented in favor of the Genetic Hypothesis will be familiar to those with a passing interest in the science. For instance, if, as the supporters of the cultural model argue, language is absorbed in a cultural context, with the mind acting as a general purpose learning machine, brain defects that affect overall intelligence would be expected to impair language in like manner. This is not what happens. Language-impaired individuals are often of average intelligence. Moreover, the existence of linguistic idiot savants, that is people with highly developed language but below normal intelligence, deals a severe blow to the learning model of language acquisition.

“If language is an instinct,” says Pinker, “it should have an identifiable seat in the brain.” This, effectively, is what is seen with deficits that occur as a result of trauma to different areas of the brain: sometimes syntax is affected, sometimes the recognition of nouns, other times the ability to use certain verbs. There does appear to be an identifiable seat of language, or, rather, several seats, interconnected in complex ways, as new research with different forms of brain scanners is beginning to show.

Pinker’s own research is with infants. Specifically, he’s interested in the errors that children make: “My teacher holded the baby rabbits”; I finded Renee”; “I love cut-upped egg.” Infant utterings of this kind, which we all think are so cute, are rich in information. “The errors children do make are rarely random garbage,” notes Pinker. “Often the errors follow the logic of grammar so beautifully that the puzzle is not why the children make the errors, but why they sound like errors to adult ears.” The infants are not repeating what they hear in daily discourse, but are logically extrapolating standard rules to irregular cases.

A new line of evidence that supports innatism, mentioned by Jackendoff and savored by Pinker, is the discovery by a Canadian linguist of a grammatical defect in otherwise normal members of a British family. Geneticists have shown that the deficit is inherited as “a single dominant gene, just like pink flowers on Gregor Mendel’s pea plants,” says Pinker. This was the research that inspired Erma Bombeck’s philosophical musings on grammar genes. There is, however, no such thing as a grammar gene. “A single gene is thought to disrupt grammar,” explains Pinker, “but that does not mean a single gene controls grammar.” Many genes are likely to be involved.

Clearly, Pinker and Jackendoff are champions of the Chomskian position, but they depart in at least one important direction. Although Chomsky views language ability as the product of a language organ, he argues that it is not the product of conventional Darwinian evolution. Instead, he suggests, it emerged when the brain passed a critical size threshold in human prehistory.

By contrast, both Pinker and Jackendoff see language as the product of evolution based on selection of primitive communication skills in our early ancestors. Pinker, particularly, is an ardent champion of natural selection, and argues that spoken language began to emerge very early in human prehistory. Chomsky “has it backwards,” he asserts: Humans didn’t develop language because they evolved big brains; brains got bigger as a result of the gradual elaboration of structures that underlie language. There are anthropologists who would contest the suggestion that language has ancient roots. But there is neurological evidence that indicates that the major changes that occurred in the human brain as it expanded involved principally those regions associated with language.

And so the arguments go on . . . and on . . . and on. There is surely no resolution in sight, but interested observers are well served by Pinker’s and Jackendoff’s different expositions. And Pinker includes a wonderful chapter demolishing the stuffiness of language pedants. “It is ironic that the jeremiads wailing about how sloppy language leads to sloppy thought are themselves hairballs of loosely associated factoids and tangled non sequiturs,” he scoffs. “As for slang, I’m all for it! . . . When given a glimpse into one of these lexicons (of slang), no true language-lover can fail to be dazzled by the brilliant wordplay and wit.” Not bad for a supposedly stuffy scholar from MIT.