H. Stuart Hughes, 83, a leading authority on European cultural and intellectual history who also was a past chairman of the National Committee for a Sane Nuclear Policy, died of pneumonia Oct. 21 in San Diego.

In presenting a 1996 Award for Scholarly Distinction to Dr. Hughes, the American Historical Association said he had "a strong claim to be the finest intellectual historian of Europe of his generation."

Dr. Hughes, an emeritus professor at the University of California at San Diego, wrote a classic trilogy of books on intellectual history.

The first volume, "Consciousness and Society," was published in 1958. It was followed in 1968 by "The Obstructed Path: French Social Thought in the Years of Desperation, 1930-1960" and his third volume, "The Sea Change: The Migration of Social Thought, 1930-1965," which looked at the center of intellectual awareness and importance traveling from Central Europe to Britain and this country. That book appeared in 1975.

Dr. Hughes was born in New York, a grandson of Charles Evans Hughes, a former New York Republican governor and chief justice of the United States. Dr. Hughes was a 1937 summa cum laude graduate of Amherst College, where he was elected to Phi Beta Kappa, and he received master's and doctoral degrees in history from Harvard University.

In 1940 and 1941, he taught at Brown University. During the war, he served with the Office of Strategic Services and the Army, attaining the rank of lieutenant colonel. After the war, he spent two years as a research official at the State Department before returning to teaching.

He taught at Harvard from 1948 to 1952, then joined the Stanford University faculty, where he became history department chairman before returning to Harvard, where he taught again from 1957 to 1969. He then taught in San Diego until 1986, when he took emeritus status.

Over the years, Dr. Hughes gained a reputation as an effective mentor of graduate students and a popular teacher of undergraduates. His writing and teaching skills may have come together best in his authorship of such books as "Contemporary Europe: A History," which appeared in 1961. It became the standard text of its day for 20th-century European history courses and went through five editions.

He also was active in current affairs, a life summed up by the title of his 1990 autobiography, "Gentleman Rebel." He chaired the National Committee for a Sane Nuclear Policy, which called for nuclear disarmament, from 1967 to 1970. In 1962, while teaching history and political science at Harvard, he ran as an independent candidate for the U.S. Senate from Massachusetts on a pro-disarmament platform. He became a vocal critic of the Vietnam War.

He made headlines in the mid-1960s when it was revealed that while conducting research in Europe, the FBI, through the State Department, had monitored his contacts and activities. The subsequent publicity resulted in the State Department announcing it would abandon such practices.

Dr. Hughes was a past president of the Society of Italian Historical Studies and founding chairman of the American Committee on the History of the Second World War.

In addition to his other books, he wrote "The United States and Italy," "History as Art and as Science" and "Oswald Spengler: A Critical Estimate." In all, he wrote 12 books, six on intellectual and cultural affairs, two on general history, three volumes of essays and his autobiography.

His marriage to the former Suzanne Rufenacht ended in divorce.

Survivors include his wife of 35 years, the former Judith Markham, of San Diego; two children from his first marriage; a son from his second marriage; and five grandchildren.