From Wikipedia, the free encyclopedia: Avram Noam Chomsky (born December 7, 1928 Philadelphia, Pennsylvania) is the Institute Professor Emeritus of linguistics at the Massachusetts Institute of Technology. Chomsky is credited with the creation of the theory of generative grammar, often considered the most significant contribution to the field of theoretical linguistics of the 20th century. He also helped spark the cognitive revolution in psychology through his review of B. F. Skinner's Verbal Behavior, which challenged the behaviorist approach to the study of mind and language dominant in the 1950s. His naturalistic approach to the study of language has also affected the philosophy of language and mind. He is also credited with the establishment of the so-called Chomsky hierarchy, a classification of formal languages in terms of their generative power. Along with his linguistics work, Chomsky is also widely known for his political activism, and for his criticism of the foreign policy of the United States and other governments. Chomsky describes himself as a libertarian socialist, a sympathizer of anarcho-syndicalism, and is often considered to be a key intellectual figure within the left wing of American politics. According to the Arts and Humanities Citation Index, between 1980 and 1992 Chomsky was cited as a source more often than any living scholar, and the eighth most cited source overall.