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Why Linguist Noam Chomsky Is a Great Scientist of Our Era

He singlehandedly rid linguistics of a stultifying (and technically mistaken) behaviorism

Noam Chomsky (right, in 2017) is, in my view, the best scientist of the past half-century. His work fascinates me, which is not a necessary criterion for being a great scientist—but it helps! I hasten to add that I do not share his politics—I’m of a conservative bent. But his theory of linguistics is brilliant and represents an anthropological, biological, and even metaphysical insight unrivaled in science since relativity and quantum mechanics. A case can be made that Chomsky’s insights are more profound than even those of modern physics, because they plumb the human soul in ways that physics cannot. To understand Chomsky’s achievement, it’s helpful to understand what linguistics was until Chomsky transformed it in the 1950s.

Philosophers and linguists have asked for millennia: How did language arise in man? The question can be asked of humanity as a whole—how and when did language arise in our ancestors? It can also be asked of each of us individually—how did each of us learn language as a child?

The evolutionary question remains unanswered, except that we now know that human language is a recent acquisition—there is good evidence that it arose no earlier than 50,000 and 100,000 years ago, which is very recent in the evolutionary time frame. There is also evidence that it arose abruptly, without any precursor. Suddenly man had language. One might even say, as I do and as Chomsky undoubtedly would, that the hominin ancestor before language was not man at all. Man began with language. How this happened is the topic of much speculation. Only the fact of the recent and sudden appearance of language seems beyond debate.

Although the evolutionary aspects of language are poorly understood, the way in which each child acquires language in infancy was thought to be well understood in the first half of the 20th century. Nearly all linguists accepted the behaviorist theories of scientists like B. F. Skinner (1904–1990). Skinner (below right) believed that children learn language by a process of trial and error, guided by reinforcement. Babies babble; when they make a sound that corresponds to a word and later a sentence in their native language, moms smile and babies say that sound again. Language acquisition is, according to behaviorists, hit and miss, with rewards for hits and punishment for misses, much like training pigeons.

The behaviorist view was orthodoxy, until Chomsky exploded it. Writing as a graduate student in the mid-1950s, Chomsky observed that there are aspects of language acquisition that do not fit this paradigm. Language has semantics and syntax. While meanings of words (semantics) does seem to be acquired by a system of trial and reward, syntax (grammar and word order) does not arise this way.

Unlike the abundant evidence for trial and error acquisition of semantics in infancy (a baby in an English-speaking family learns to say “cat” when pointing at the house pet), there is not the slightest evidence for “trial and error” syntax acquisition in infancy. Very young children use correct grammar (syntax) from the very beginning of language development. This intrinsic knowledge of grammar happens for all languages, without exception. Babies are born knowing syntax and the syntax they know is common to all languages—what Chomsky called Universal Grammar. Chomsky pointed out that these structures cannot be learned by children by trial and error. Aside from the utter lack of evidence for a process of trial and error in studies of infant language, Chomsky observed that an infant could not really have the experience needed to explain syntax acquisition that way. Even young children inherently know and use grammar rules. They construct and understand sentences of such consistency, intricacy, and complexity that it is clear that they could not have acquired this knowledge merely through incidental daily experience with language.

There is no behavioral explanation for the acquisition of grammar. Kids don’t start out with completely random jumbles of words and gradually, by a system of rewards, learn subject and verb predicates. Even very young children come fully equipped with an instinctive knowledge of grammar that is common to all languages—a “language” organ—as Chomsky called it. They learn the meaning of words with use but they instinctively know grammar from birth.

Chomsky’s opponents have at times argued that syntax could be acquired in infancy as a rider on semantics. That is, children learn the meanings of words via behaviorist trial and error. Then, using the behaviorally acquired meaning, they learn to combine the words into proper sentences accepted by language users in their environment. In this view, syntax is linked to meaning as a spandrel and thus grammar can be acquired by proxy to meaning via trial and error.

Chomsky replied that this cannot be. To illustrate why, he proposed a (now) famous sentence:

colorless green ideas sleep furiously

This sentence, which had certainly never been uttered by an English speaker before Chomsky, is nonsense—it has no semantic content. Yet, it is a perfectly proper grammatical English sentence, despite the fact that it has no semantic content whatever. Every English speaker knows that it is grammatically correct even though we have never heard it before and though we (probably) have no formal training in linguistics. To better understand how nonsense can be grammatical, consider the same sentence with the word order reversed:

furiously sleep ideas green colorless

This sentence, which contains exactly the same words, is, like the first sentence, complete nonsense. But unlike the first sentence it is grammatically jumbled. Both sense and nonsense, it seems, can have good grammar or bad grammar, quite independent of the sense or lack of sense conveyed.

This is an example of one of Chomsky’s fundamental insights: grammar is independent of semantics. I can construct an unlimited number of grammatically correct nonsensical sentences and, likewise, I can construct an infinite number of grammatically incorrect meaningful statements. If I’m asked what my wife is doing now and I reply “sleeping,” my meaning is clear even though I didn’t use valid grammar (“sleeping” isn’t a sentence). I can make an infinite number of similarly grammatically incorrect but meaningful utterances, and I can also make an infinite number of grammatically correct but meaningless sentences. Try it—it’s fun!

Syntax and semantics don’t overlap and therefore an infant cannot learn syntax via linkage to the semantic content of words. Meaning can be acquired via the behaviorist paradigm but grammar cannot. Grammar has a structure and internal logic that is not learned by young children—toddlers don’t study sentence structure and it is far too profound and complex to be acquired as a spandrel by just listening to the spoken language of others. Human beings, alone among animals, know correct grammar from birth, before they have spoken or heard a single word.

There is much more to Chomsky’s linguistic theory than what I have recounted here—Chomsky’s insights are a vast realm of wisdom. It’s worth noting that in the mid-20th century his theory of Universal Grammar put a sudden end to the behaviorist paradigm in linguistics and more or less founded the field of cognitive science. Within a decade of Chomsky’s first book Syntactic Structures, behaviorism was swept from the field. Although stirring have been heard of late, I think it’s fair to say that behaviorism as a science is dead. Indeed, if Chomsky had done nothing but bury behaviorism, that alone should have earned him humanity’s undying gratitude.

Chomsky’s insight that language is an in-born “organ” unique to humans is of obvious relevance to our understanding of human exceptionalism. Chomsky showed that no animal has language of any sort and that human language did not evolve from animal behavior and is not acquired by a behavioral system of rewards and punishments. This is not to say that non-human animals do not link meanings to sounds—they certainly do—but animals do not structure their sounds and gestures syntactically. Animals have no grammar, and grammar is the hallmark of language.

In Wilhelm von Humboldt’s famous insight, grammar is what enables language to “[make] infinite use of finite means.” By that, he means that we can generate an infinite number of sentences—and express an infinite number of ideas—from a finite number of grammatical rules. This echoes Aristotle’s beautiful aphorism on the soul—that “the soul is, in a way, all things.” Only humans are born with a language organ, whatever material (or immaterial) form it takes and this organ distinguishes us fundamentally from animals. In this sense, as I have said elsewhere, we are more different from apes than apes are from viruses.

Despite Chomsky’s genius—that is not too strong a word for his theory of language—he has faltered badly in his attempts to explain the biology of language, that is, to explain the biological basis for the human language organ. That is a very important topic and grist for another post.

Note: For readers interested in exploring Chomsky’s work, his book What Kind of Creatures are We? is a fine introduction.

Editor’s note: The retouched photo of Noam Chomsky is courtesy Wugapodes (CC BY 4.0). The photo of B.F. Skinner circa 1950 is courtesy Silly Rabbit (CC BY 3.0)

Also by Michael Egnor on language:

The real reason why only human beings speak. Language is a tool for abstract thinking—a necessary tool for abstraction—and humans are the only animals who think abstractly.


How is human language different from animal signals? What do we need from language that we cannot get from signals alone?

Michael Egnor

Senior Fellow, Center for Natural & Artificial Intelligence
Michael R. Egnor, MD, is a Professor of Neurosurgery and Pediatrics at State University of New York, Stony Brook, has served as the Director of Pediatric Neurosurgery, and award-winning brain surgeon. He was named one of New York’s best doctors by the New York Magazine in 2005. He received his medical education at Columbia University College of Physicians and Surgeons and completed his residency at Jackson Memorial Hospital. His research on hydrocephalus has been published in journals including Journal of Neurosurgery, Pediatrics, and Cerebrospinal Fluid Research. He is on the Scientific Advisory Board of the Hydrocephalus Association in the United States and has lectured extensively throughout the United States and Europe.

Why Linguist Noam Chomsky Is a Great Scientist of Our Era