Chomsky hierarchy

Chomsky is famous for investigating various kinds of formal languages and whether or not they might be capable of capturing key properties of human language. His Chomsky hierarchy partitions formal grammars into classes, or groups, with increasing expressive power, i.e., each successive class can generate a broader set of formal languages than the one before. Interestingly, Chomsky argues that modeling some aspects of human language requires a more complex formal grammar (as measured by the Chomsky hierarchy) than modeling others. For example, while a regular language is powerful enough to model English morphology, it is not powerful enough to model English syntax. In addition to being relevant in linguistics, the Chomsky hierarchy has also become important in computer science(especially in compiler construction and automata theory).

Contributions to linguistics

Chomskyan linguistics, beginning with his Syntactic Structures, a distillation of his Logical Structure of Linguistic Theory (1955, 75), challenges structural linguistics and introduces transformational grammar. This theory takes utterances (sequences of words) to have a syntax which can be characterized by a formal grammar; in particular, a context-free grammar extended with transformational rules.

Children are hypothesized to have an innate knowledge of the basic grammatical structure common to all human languages (i.e., they assume that any language which they encounter is of a certain restricted kind). This innate knowledge is often referred to as universal grammar. It is argued that modeling knowledge of language using a formal grammar accounts for the "productivity" of language: with a limited set of grammar rules and a finite set of terms, humans are able to produce an infinite number of sentences, including sentences no one has previously said. He has always acknowledged his debt toPāṇini for his modern notion of an explicit generative grammar. This is related to Rationalist ideas of a priori knowledge, in that it is not due to experience.

The Principles and Parameters approach (P&P)—developed in his Pisa 1979 Lectures, later published as Lectures on Government and Binding (LGB)—make strong claims regarding universal grammar: that the grammatical principles underlying languages are innate and fixed, and the differences among the world's languages can be characterized in terms of parameter settings in the brain (such as the pro-drop parameter, which indicates whether an explicit subject is always required, as in English, or can be optionally dropped, as in Spanish), which are often likened to switches. (Hence the term principles and parameters, often given to this approach.) In this view, a child learning a language need only acquire the necessary lexical items (words, grammatical morphemes, and idioms), and determine the appropriate parameter settings, which can be done based on a few key examples.

Proponents of this view argue that the pace at which children learn languages is inexplicably rapid, unless children have an innate ability to learn languages. The similar steps followed by children all across the world when learning languages, and the fact that children make certain characteristic errors as they learn their first language, whereas other seemingly logical kinds of errors never occur (and, according to Chomsky, should be attested if a purely general, rather than language-specific, learning mechanism were being employed), are also pointed to as motivation for innateness.

More recently, in his Minimalist Program (1995), while retaining the core concept of "principles and parameters", Chomsky attempts a major overhaul of the linguistic machinery involved in the LGB model, stripping from it all but the barest necessary elements, while advocating a general approach to the architecture of the human language faculty that emphasizes principles of economy and optimal design, reverting to a derivational approach to generation, in contrast with the largely representational approach of classic P&P.

In 1999, research done at the Grabscheid Clinical and Research Center for Voice Disorders at Mount Sinai Hospital in New York City showed that slow tonic muscle fibers in the muscles of human vocal cords do not exist in other mammals, creating support and a possible explanation for Chomsky's theories.^[29]

Chomsky's ideas have had a strong influence on researchers investigating the acquisition of language in children, though some^[specify] researchers who work in this area today do not support Chomsky's theories, instead advocating emergentist or connectionist theories reducing language to an instance of general processing mechanisms in the brain.

He also theorizes that unlimited extension of a language such as English is possible only by therecursive device of embedding sentences in sentences.^{[citation needed]}

His best-known work in phonology is The Sound Pattern of English (1968), written with Morris Halle (and often known as simply SPE). This work has had a great significance for the development in the field. While phonological theory has since moved beyond "SPE phonology" in many important respects, the SPE system is considered the precursor of some of the most influential phonological theories today, including autosegmental phonology, lexical phonology and optimality theory. Chomsky no longer publishes on phonology.

Noam Chomsky

Avram Noam Chomsky (pronounced /noʊm ˈtʃɑmski/; born December 7, 1928) is an American linguist,philosopher,^[2][3][4] cognitive scientist, political activist,author, and lecturer. He is an Institute Professor emeritusand professor emeritus of linguistics at the Massachusetts Institute of Technology.^[5] Chomsky is well known in the academic and scientific community as the father of modernlinguistics.^[6][7] Since the 1960s, he has become known more widely as a political dissident, an anarchist,^[8] and alibertarian socialist intellectual.

In the 1950s, Chomsky began developing his theory ofgenerative grammar, which has undergone numerous revisions and has had a profound influence on linguistics. He also established the Chomsky hierarchy, a classification offormal languages in terms of their generative power. In 1959, Chomsky published a widely influential review of B. F. Skinner's theoretical book Verbal Behavior, which was the first attempt by a Radical Behaviorist to provide a functional,operant analysis of language. Chomsky used this review to broadly and aggressively challenge the behavioristapproaches to studies of behavior dominant at the time and contributed to the cognitive revolution in psychology. His naturalistic^[9] approach to the study of language has affected the philosophy of language and mind.^[10] Randy Harris, author of The Linguistics Wars, has described him as: "a hero of Homeric proportions, belonging solidly in the pantheon of our country's finest minds, with all the powers and qualities thereof. First, foremost, and initially he is staggeringly smart. The speed, scope, and synthetic abilities of his intellect are legendary. He is, too, a born leader, able to marshal support, fierce and uncompromising support, for positions he develops or adopts. Often, it seems, he shapes linguistics by sheer force of will."^[11]

Beginning with his opposition to the Vietnam War, Chomsky established himself as a prominent critic of US foreign and domestic policy. He is a self-declared adherent of libertarian socialism which he regards as "the proper and natural extension of classical liberalism into the era of advanced industrial society."^[12]

According to the Arts and Humanities Citation Index in 1992, Chomsky was cited as a source more often than any other living scholar during the 1980–92 period, and was the eighth most-cited source.^[13][14][15] He is also considered a prominent cultural figure.^[16] At the same time, his status as a leading critic of US foreign policy has made him controversial.