Professionally, Hayakawa was a psychologist, semanticist, teacher and writer. He was an instructor at the University of Wisconsin from 1936 to 1939 and at the Armour Institute of Technology from 1939 to 1947. Hayakawa was an important semanticist. His first book on the subject, Language in Thought and Action, was published in 1949 as an expansion of the earlier work, Language in Action, written since 1938 and published in 1941 to be a Book-of-the-Month Club selection. It is currently in its fifth edition and has greatly helped popularize Alfred Korzybski's general semantics and in effect semantics in general, while semantics or theory of meaning was overwhelmed by mysticism, propagandism and even scientism. In the preface, Hayakawa cautioned:

The original version of this book, Language in Action, published in 1941, was in many respects a response to the dangers of propaganda, especially as exemplified in Adolf Hitler's success in persuading millions to share his maniacal and destructive views. It was the writer's conviction then, as it remains now, that everyone needs to have a habitually critical attitude towards language — his own as well as that of others — both for the sake of his personal well being and for his adequate functioning as a citizen. Hitler is gone, but if the majority of our fellow citizens are more susceptible to the slogans of fear and race hatred than to those of peaceful accommodation and mutual respect among human beings, our political liberties remain at the mercy of any eloquent and unscrupulous demagogue.

In addition to such motivation, he acknowledged his debt as follows:

My deepest debt in this book is to the General Semantics ('non-Aristotelian system') of Alfred Korzybski. I have also drawn heavily upon the works of other contributors to semantic thought: especially C. K. Ogden and I. A. Richards, Thorstein Veblen, Edward Sapir, Leonard Bloomfield, Karl R. Popper, Thurman Arnold, Jerome Frank, Jean Piaget, Charles Morris, Wendell Johnson, Irving J. Lee, Ernst Cassirer, Anatol Rapoport, Stuart Chase. I am also deeply indebted to the writings of numerous psychologists and psychiatrists with one or another of the dynamic points of view inspired by Sigmund Freud: Karl Menninger, Trigant Burrow, Carl Rogers, Kurt Lewin, N. R. F. Maier, Jurgen Ruesch, Gregory Bateson, Rudolf Dreikurs, Milton Rokeach. I have also found extremely helpful the writings of cultural anthropologists, especially those of Benjamin Lee Whorf, Ruth Benedict, Clyde Kluckhohn, Leslie A. White, Margaret Mead, Weston La Barre.

He was a lecturer at the University of Chicago from 1950 to 1955. During this time he presented a talk at the 1954 Conference of Activity Vector Analysts at Lake George, New York in which he discussed a theory of personality from the semantic point of view. This was later published as The Semantic Barrier. This was a definitive lecture as it discussed the Darwinism of the "survival of self" as contrasted with the "survival of self-concept".

Hayakawa was an English professor at San Francisco State College (now called San Francisco State University) from 1955 to 1968. In the early 1960s, he helped organize the Anti Digit Dialing League, a group in San Francisco that opposed the introduction of all digit telephone exchange names. Among the students he trained were commune leader Stephen Gaskin and author Gerald Haslam. He became president of San Francisco State College during the turbulent period of 1968 to 1973, becoming president emeritus in 1973 and then wrote a column for the Register & Tribune Syndicate from 1970 to 1976.

Student strike at San Francisco State University

During 1968-69, there was a bitter student strike at San Francisco State University that was a major news event at the time and chapter in the radical history of the United States and the Bay Area. The strike was led by the Third World Liberation Front supported by Students for a Democratic Society, the Black Panthers and the counter-cultural community, among others. It demanded an end to racism, creation of an Ethnic Studies Department, to be chaired by sociologist Nathan Hare, an end to the War in Vietnam and the university's complicity with it. Hayakawa became popular with mainstream voters in this period after he pulled the wires out from the speakers on a student van at an outdoor rally, dramatically disrupting it. Yaga.com

He was elected in California as a Republican to the United States Senate in 1976, defeating incumbent Democrat John V. Tunney. Hayakawa served from January 3, 1977 to January 3, 1983. He did not stand for reelection in 1982 and was succeeded by Republican Pete Wilson.

Hayakawa founded the political lobbying organization U.S. English, which is dedicated to making the English language the official language of the United States.

The Senator was a resident of Mill Valley, California until his death in Greenbrae, California, in 1992. He was also a member of the Bohemian Club. He also had an abiding interest in traditional jazz and wrote extensively on that subject, including several erudite sets of album liner notes. Sometimes in his lectures on semantics, he was joined by the respected traditional jazz pianist, Don Ewell, whom Hayakawa employed to demonstrate various points in which he analyzed semantic and musical principles.

• Karagueuzian, Dikran. Blow It Up! The Black Student Revolt at San Francisco State College and the Emergence of Dr. Hayakawa. Boston: Gambit, 1971.

• Hayakawa, S.I. Choose the Right Word: A Modern Guide to Synonyms and Related Words. 1968. Reprint. New York: Perennial Library, 1987. Originally published as Funk & Wagnalls Modern Guide to Synonyms and Related Words.

• Hayakawa, S.I. “Education Revisited.” In The World Today, edited by Phineas J. Sparer. Memphis: Memphis State University Press, 1975.

• Hayakawa, S.I. Language in Thought and Action. 1939. Enlarged ed. San Diego: Harcourt Brace Jovanovich, 1978. Originally published as Language in Action.

• Hayakawa, S.I. Symbol, Status, and Personality. New York: Harcourt, Brace & World, 1963.

• Hayakawa, S.I. Through the Communication Barrier: On Speaking, Listening, and Understanding. Edited by Arthur Chandler. New York: Harper & Row, 1979.

• Hayakawa, S.I. , ed. Language, Meaning, and Maturity. New York: Harper & Brothers, 1954.

• Hayakawa, S.I. , ed. Our Language and Our World. 1959. Reprint. Freeport, NY: Books for Libraries Press, 1971.

• Hayakawa, S.I. , ed. The Use and Misuse of Language. Greenwich, CT: Fawcett Publications, 1964.

• Hayakawa, S.I., and William Dresser, eds. Dimensions of Meaning. Indianapolis: Bobbs-Merrill Co., 1970. Includes Hayakawa’s essays, “General Semantics and the Cold War Mentality,” and “Semantics and Sexuality.”

• Paris, Richard, and Janet Brown, eds. Quotations from Chairman S.I. Hayakawa. San Francisco: n.p., 1969.

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