The idea that we have brains hardwired with a mental template for learning grammar — famously espoused by Noam Chomsky of the Massachusetts Institute of Technology — has dominated linguistics for almost half a century. Recently, though, cognitive scientists and linguists have abandoned Chomsky’s “universal grammar” theory in droves because of new research examining many different languages — and the way young children learn to understand and speak the tongues of their communities. That work fails to support Chomsky’s assertions.

The research suggests a radically different view, in which learning of a child’s first language does not rely on an innate grammar module. Instead the new research shows that young children use various types of thinking that may not be specific to language at all — such as the ability to classify the world into categories (people or objects, for instance) and to understand the relations among things. These capabilities, coupled with a unique hu­­­man ability to grasp what others intend to communicate, allow language to happen. The new findings indicate that if researchers truly want to understand how children, and others, learn languages, they need to look outside of Chomsky’s theory for guidance.

This conclusion is important because the study of language plays a central role in diverse disciplines — from poetry to artificial intelligence to linguistics itself; misguided methods lead to questionable results. Further, language is used by humans in ways no animal can match; if you understand what language is, you comprehend a little bit more about human nature.

Chomsky’s first version of his theory, put forward in the mid-20th century, meshed with two emerging trends in Western intellectual life. First, he posited that the languages people use to communicate in everyday life behaved like mathematically based languages of the newly emerging field of computer science. His research looked for the underlying computational structure of language and proposed a set of procedures that would create “well-formed” sentences. The revolutionary idea was that a computerlike program could produce sentences real people thought were grammatical. That program could also purportedly explain as well the way people generated their sentences. This way of talking about language resonated with many scholars eager to em­­brace a computational approach to, well, everything.

As Chomsky was developing his computational theories, he was simultaneously proposing that they were rooted in human biology. In the second half of the 20th century, it was becoming ever clearer that our unique evolutionary history was responsible for many aspects of our unique human psychology, and so the theory resonated on that level as well. His universal grammar was put forward as an innate component of the human mind — and it promised to reveal the deep biological underpinnings of the world’s 6,000-plus human languages. The most powerful, not to mention the most beautiful, theories in science reveal hidden unity underneath surface diversity, and so this theory held immediate appeal.

But evidence has overtaken Chomsky’s theory, which has been inching toward a slow death for years. It is dying so slowly because, as physicist Max Planck once noted, older scholars tend to hang on to the old ways: “Science progresses one funeral at a time.”

In the beginning

The earliest incarnations of universal grammar in the 1960s took the underlying structure of “standard average European” languages as their starting point — the ones spoken by most of the linguists working on them. Thus, the universal grammar program operated on chunks of language, such as noun phrases (“The nice dogs”) and verb phrases (“like cats”).

Fairly soon, however, linguistic comparisons among multiple languages began rolling in that did not fit with this neat schema. Some native Australian languages, such as Warlpiri, had grammatical elements scattered all over the sentence — noun and verb phrases that were not “neatly packaged” so that they could be plugged into Chomsky’s universal grammar — and some sentences had no verb phrase at all.

These so-called outliers were difficult to reconcile with the universal grammar that was built on examples from European languages. Other exceptions to Chomsky’s theory came from the study of “ergative” languages, such as Basque or Urdu, in which the way a sentence subject is used is very different from that in many European languages, again challenging the idea of a universal grammar.

Illustration by Lucy Reading-Ikkanda

These findings, along with theoretical linguistic work, led Chomsky and his followers to a wholesale revision of the notion of universal grammar during the 1980s. The new version of the theory, called principles and parameters, replaced a single universal grammar for all the world’s languages with a set of “universal” principles governing the structure of language. These principles manifested themselves differently in each language. An analogy might be that we are all born with a basic set of tastes (sweet, sour, bitter, salty and umami) that interact with culture, history and geography to produce the present-day variations in world cuisine. The principles and parameters were a linguistic analogy to tastes. They interacted with culture (whether a child was learning Japanese or English) to produce today’s variation in languages as well as defined the set of human languages that were possible.

Languages such as Spanish form fully grammatical sentences without the need for separate subjects — for example, Tengo zapatos (“I have shoes”), in which the person who has the shoes, “I,” is indicated not by a separate word but by the “o” ending at the end of the verb. Chomsky contended that as soon as children encountered a few sentences of this type, their brains would set a switch to “on,” indicating that the sentence subject should be dropped. Then they would know that they could drop the subject in all their sentences.

The “subject-drop” parameter supposedly also determined other structural features of the language. This notion of universal principles fits many European languages reasonably well. But data from non-European languages turned out not to fit the revised version of Chomsky’s theory. Indeed, the research that had at­­tempted to identify parameters, such as the subject-drop, ultimately led to the abandonment of the second incarnation of universal grammar because of its failure to stand up to scrutiny.

More recently, in a famous paper published in Science in 2002, Chomsky and his co-authors described a universal grammar that included only one feature, called computational recursion (although many advocates of universal grammar still prefer to assume there are many universal principles and parameters). This new shift permitted a limited number of words and rules to be combined to make an unlimited number of sentences.

The endless possibilities exist because of the way recursion embeds a phrase within another phrase of the same type. For example, English can embed phrases to the right (“John hopes Mary knows Peter is lying”) or embed centrally (“The dog that the cat that the boy saw chased barked”). In theory, it is possible to go on embedding these phases infinitely. In practice, understanding starts to break down when the phrases are stacked on top of one another as in these examples. Chomsky thought this breakdown was not directly related to language per se. Rather it was a limitation of human memory. More important, Chomsky proposed that this recursive ability is what sets language apart from other types of thinking such as categorization and perceiving the relations among things. He also proposed recently this ability arose from a single genetic mutation that occurred be­tween 100,000 and 50,000 years ago.

As before, when linguists actually went looking at the variation in languages across the world, they found counterexamples to the claim that this type of recursion was an essential property of language. Some languages — the Amazonian Pirahã, for in­­stance — seem to get by without Chomskyan recursion.

As with all linguistic theories, Chomsky’s universal grammar tries to perform a balancing act. The theory has to be simple enough to be worth having. That is, it must predict some things that are not in the theory itself (otherwise it is just a list of facts). But neither can the theory be so simple that it cannot explain things it should. Take Chomsky’s idea that sentences in all the world’s languages have a “subject.” The problem is the concept of a subject is more like a “family resemblance” of features than a neat category. About 30 different grammatical features define the characteristics of a subject. Any one language will have only a subset of these features — and the subsets often do not overlap with those of other languages.

Chomsky tried to define the components of the essential tool kit of language — the kinds of mental machinery that allow hu­­man language to happen. Where counterexamples have been found, some Chomsky defenders have responded that just be­­cause a language lacks a certain tool — recursion, for example — does not mean that it is not in the tool kit. In the same way, just because a culture lacks salt to season food does not mean salty is not in its basic taste repertoire. Unfortunately, this line of reasoning makes Chomsky’s proposals difficult to test in practice, and in places they verge on the unfalsifiable.

Death knells

A key flaw in Chomsky’s theories is that when applied to language learning, they stipulate that young children come equipped with the capacity to form sentences using abstract grammatical rules. (The precise ones depend on which version of the theory is in­­voked.) Yet much research now shows that language acquisition does not take place this way. Rather young children begin by learning simple grammatical patterns; then, gradually, they intuit the rules behind them bit by bit.

Thus, young children initially speak with only concrete and simple grammatical constructions based on specific patterns of words: “Where’s the X?”; “I wanna X”; “More X”; “It’s an X”; “I’m X-ing it”; “Put X here”; “Mommy’s X-ing it”; “Let’s X it”; “Throw X”; “X gone”; “Mommy X”; “I Xed it”; “Sit on the X”; “Open X”; “X here”; “There’s an X”; “X broken.” Later, children combine these early patterns into more complex ones, such as “Where’s the X that Mommy Xed?”

Many proponents of universal grammar accept this characterization of children’s early grammatical development. But then they assume that when more complex constructions emerge, this new stage reflects the maturing of a cognitive capacity that uses universal grammar and its abstract grammatical categories and principles.

For example, most universal grammar approaches postulate that a child forms a question by following a set of rules based on grammatical categories such as “What (object) did (auxiliary) you (subject) lose (verb)?” Answer: “I (subject) lost (verb) something (object).” If this postulate is correct, then at a given developmental period children should make similar errors across all wh-question sentences alike. But children’s errors do not fit this prediction. Many of them early in development make errors such as “Why he can’t come?” but at the same time as they make this error — failing to put the “can’t” before the “he” — they correctly form other questions with other “wh-words” and auxiliary verbs, such as the sentence “What does he want?”

Experimental studies confirm that children produce correct question sentences most often with particular wh-words and auxiliary verbs (often those with which they have most experience, such as “What does…;”), while continuing to make errors with question sentences containing other (often less frequent) combinations of wh-words and auxiliary verbs: “Why he can’t come?”