A Simple Introduction
This book was about syntax: the rules by which sentences are constructed in a language. Chomsky’s goal was to construct a formal, explicit, “generative” grammar of English—a device that would generate all and only the grammatical sentences of the language.
The book does not mention cognitive science. The field did not yet exist under that name. It treats grammar as a formal system, independent of meaning, independent of statistics, and independent of the behaviorist psychology that dominated American academia at the time. What matters is not how people actually speak, but what the underlying rules of the language must be for anyone to speak it at all.
But this austere, technical proposal had a profound effect on how psychologists, philosophers, and linguists came to think about the mind. If language could be described by a formal system of rules, if those rules were not learned through association but were part of the human biological endowment, if the mind could be studied as a rule-governed system rather than a black box—then the mind could be studied scientifically again. The vocabulary of Chomsky’s book—generative grammar, phrase structure, transformational rules, competence, kernel sentences—became the vocabulary of the cognitive revolution . The book is not cognitive science, but it made cognitive science possible.
10 Key Takeaways for Cognitive Science and Learning
- Grammar is autonomous. Chomsky argued that grammar is independent of meaning. The sentence “Colorless green ideas sleep furiously” is grammatical though nonsensical, while “Furiously sleep ideas green colorless” is not . This severed the study of syntax from semantics and made linguistics a formal science.
- Language cannot be described by statistics. Chomsky rejected the idea that grammatical sentences are those with high statistical probability. A sentence can be entirely novel and still grammatical; a sequence of common words can be ungrammatical. Grammar is a matter of rules, not frequencies.
- Finite-state models are inadequate. Chomsky showed that English contains sentences with mirror-image dependencies (like “if… then” constructions nested within one another) that cannot be generated by a finite-state Markov process. A more powerful device is required.
- Phrase structure is necessary but not sufficient. Chomsky introduced phrase structure rules (like Sentence → NP + VP) to capture the hierarchical constituent structure of sentences. But he showed that phrase structure alone cannot account for important linguistic relations, such as the active-passive relation.
- Transformational rules are essential. Chomsky proposed a new level of analysis: transformations. The passive sentence “The ball was hit by the man” is derived from the active “The man hit the ball” by a transformational rule. This explained relations between sentences that phrase structure could not .
- The kernel is the foundation. Chomsky distinguished kernel sentences—simple, declarative, active sentences—from all other sentences, which are derived from kernels by transformations. This provided a simple and powerful model of English syntax.
- The goals of linguistic theory are modest. Chomsky argued that linguistics should seek an evaluation procedure—a way of choosing between competing grammars—rather than a discovery procedure—a mechanical method for constructing a grammar from raw data. This made linguistics a theoretical science, not a taxonomic one.
- Competence differs from performance. Though not fully developed in Syntactic Structures, the seeds were planted for the distinction between what a speaker knows (competence) and what they actually do (performance). This distinction became central to cognitive science .
- The speaker is not a finite-state machine. Chomsky argued that a speaker can produce and understand an indefinite number of new sentences on the basis of finite experience. This creative aspect of language use could not be explained by behaviorist stimulus-response psychology.
- The mind is a rule-governed system. By describing language as a formal system of rules, Chomsky provided a model for studying the mind as an information-processing system. This was a direct challenge to behaviorism and a foundation for the cognitive revolution.
To him, “The fundamental aim in the linguistic analysis of a language L is to separate the grammatical sequences which are the sentences of L from the ungrammatical sequences which are not sentences of L and to study the structure of the grammatical sequences.”
The Formal Problem: Chomsky’s goal was to construct a device that would generate all and only the grammatical sentences of a language. To do this, he needed to determine what kind of grammar is required—what levels of representation, what kinds of rules.
Grammar as Autonomy: In Chomsky’s theory, “grammatical” does not mean “meaningful.” It means “generated by the rules of the grammar.” This independence of syntax from semantics was a radical departure from the tradition that treated language as an instrument of communication.
The Book’s Core Ideas
Chomsky’s book is technical and compressed, but its central ideas can be stated simply.
Finite-state grammars. Chomsky begins by considering the simplest possible model of language: a finite-state Markov process that produces sentences from left to right. He shows that this model is inadequate: English contains sentences with nested dependencies that a finite-state machine cannot generate.
Phrase structure. The next model is phrase structure grammar, based on immediate constituent analysis. Rules like Sentence → NP + VP and VP → Verb + NP generate sentences with hierarchical structure. This model is more powerful than the finite-state model, but Chomsky shows it is still inadequate.
Transformations. The solution is to add a new level: transformational rules. These rules operate on strings with a given phrase structure and convert them into new strings. The passive transformation, for example, converts an active sentence into a passive one. Transformations explain relations between sentences that phrase structure cannot.
The kernel. Chomsky distinguishes kernel sentences—simple, active, declarative sentences—from non-kernel sentences, which are derived by transformations. The kernel provides the foundation on which all other sentences are built.
The goals of linguistic theory. Chomsky argues that linguistics should seek an evaluation procedure for grammars, not a discovery procedure. The question is not how to mechanically construct a grammar from data, but how to compare competing grammars and determine which is simpler and more adequate.
The autonomy of grammar. Chomsky argues that grammar is independent of meaning. The notion of grammaticalness cannot be identified with meaningfulness or with statistical frequency. This claim was central to the development of linguistics as a formal science.
From Linguistics to Mind: How Chomsky Shaped Cognitive Science
Chomsky’s book was not about cognitive science, but it became a cornerstone of cognitive science for several reasons.
The cognitive revolution. Syntactic Structures is widely regarded as one of the works that began the cognitive revolution. By demonstrating that language could be described by a formal system of rules, Chomsky provided a model for studying the mind as a rule-governed system. This was a direct challenge to behaviorism, which treated the mind as a black box .
The critique of behaviorism. Chomsky’s 1959 review of Skinner’s Verbal Behavior—building on the foundation laid in Syntactic Structures—was a devastating critique of behaviorist accounts of language. The review argued that language acquisition could not be explained by reinforcement and association; the child must be equipped with innate knowledge of grammatical structure. This critique helped to open the way for cognitive psychology.
The computational theory of mind. Chomsky’s generative grammar was a computational system: a set of rules that could, in principle, be implemented by a machine. This provided a model for the computational theory of mind, which became the dominant paradigm in cognitive science.
The competence-performance distinction. Though only implicit in Syntactic Structures, the distinction between what a speaker knows and what they do became central to cognitive science. It allowed linguists and psychologists to study the underlying system of knowledge independently of the messy details of actual performance.
The debate about innateness. Chomsky’s claim that the basic principles of grammar are innate—part of the human biological endowment—provoked decades of debate in cognitive science and developmental psychology. This debate continues today.
Chomsky and Learning Science
Chomsky’s theory has several implications for the science of learning, some direct and some indirect.
Learning as rule acquisition, not habit formation. If language is a rule-governed system, then learning a language is not a matter of forming habits through repetition and reinforcement. It is a matter of acquiring the rules of the system. This has implications for how we think about learning in general: not as the accumulation of associations, but as the construction of internal models.
The poverty of the stimulus. Chomsky argued that the linguistic input children receive is too impoverished to account for the grammatical knowledge they acquire. This “poverty of the stimulus” argument suggests that some knowledge must be innate. The debate about how much of learning is innate and how much is acquired remains central to learning science.
The limits of the analogy. Chomsky’s theory is about the structure of language, not about learning. It tells us what the child must acquire, but not how the child acquires it. Later work in cognitive science and developmental psychology has tried to fill this gap. The tension between formal competence and actual learning remains one of the central problems in learning science.
Conclusion
Chomsky’s 1957 book is not a cognitive science paper. It is a linguistics book about the formal structure of sentences. But it is one of the founding documents of cognitive science because it made the mind a legitimate object of scientific study again—and in doing so, it made it possible to study the mind as a rule-governed, information-processing system.
The book’s legacy is everywhere in modern cognitive science. The idea of generative grammar underlies research on language processing and acquisition. The competence-performance distinction underlies research on linguistic knowledge. The critique of behaviorism opened the way for cognitive psychology. The debate about innateness continues to shape developmental science.
Chomsky himself was not interested in psychology. He was interested in the structure of language. But his theory of language became a theory of mind—or at least, the framework within which a theory of mind became possible. The book is a reminder that the most important advances in one field often come from another. And it is a reminder that grammar, once made formal, becomes a tool for understanding everything—including the mind.
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