NOAM CHOMSKY is an American linguist, philosopher, cognitive scientist, political activist, author, and lecturer. He is an Institute Professor and professor emeritus of linguistics at the Massachusetts Institute of Technology, and is well known in the academic and scientific community as one of the fathers of modern linguistics. In the 1950s, Chomsky began developing his theory of generative grammar, which has undergone numerous revisions and has had a profound influence on linguistics. His approach to the study of language emphasizes "an innate set of linguistic principles shared by all humans" known as universal grammar, "the initial state of the language learner," and discovering an "account for linguistic variation via the most general possible mechanisms." He also established the Chomsky hierarchy, a classification of formal languages in terms of their generative power. Since the 1960s, he has become known more widely as a political dissident, an anarchist, and a libertarian socialist intellectual. Beginning with his opposition to the Vietnam War, Chomsky established himself as a prominent critic of US foreign and domestic policy. In February 1967, Chomsky became one of the leading opponents of the war with the publication of his essay, "THE RESPONSIBILITY OF INTELLECTUALS," in The New York Review of Books. This was followed by his 1969 book, AMERICAN POWER AND THE NEW MANDARINS, a collection of essays that placed him at the forefront of American dissent. A prolific author, Chomsky has written dozens of books, including THE FATEFUL TRIANGLE: THE UNITED STATES, ISRAEL, AND THE PALESTINIANS (1983), MANUFACTURING CONSENT: THE POLITICAL ECONOMY OF THE MASS MEDIA, with E. S. Herman (1988), NECESSARY ILLUSIONS: THOUGHT CONTROL IN DEMOCRATIC SOCIETIES (1989), 9-11 (2001), UNDERSTANDING POWER: THE INDISPENSABLE CHOMSKY (2002), HEGEMONY OR SURVIVAL: AMERICA'S QUEST FOR DOMINANCE (2003), and HOPE AND PROSPECTS (forthcoming, 2010). His far-reaching criticisms of US foreign policy and the legitimacy of US power have made him a controversial figure: largely shunned by the mainstream media in the United States, he is frequently sought out for his views by publications and news outlets worldwide. 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. He is also 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."