In the presidential election of 1948, he voted for the Socialist Norman Thomas, not the Democrat Harry S. Truman.

Two groups of thinkers that have had a lasting impact on American culture had a lasting impact on Mr. Glazer as well. The first was the New York Intellectuals, the collection of writers, gathered around Partisan Review and later The New York Review of Books, who combined leftist politics with modernist aesthetics. The Partisan Review writers Dwight Macdonald and Hannah Arendt were early influences; another contributor to the magazine, the art critic Clement Greenberg, helped get him his first job.

While he was at Commentary, Mr. Glazer’s circle widened. Writers like James Baldwin and Irving Howe would drop by the office, and at Greenwich Village parties he met prominent intellectuals like Lionel Trilling and the Partisan Review editors Philip Rahv and William Phillips. These were people, Mr. Glazer said, who seemed to be “working at the forefront of knowledge,” with their understanding of Marx, Freud and Modernist developments in the arts.

“There was an awful lot of talk,” Mr. Glazer said, but he had always felt that he was something of an outsider, a “junior member” at these get-togethers, “more like a hanger-on” than a full participant.

Mr. Glazer’s turn to neoconservatism followed an almost paradigmatic path. Throughout the 1950s, and even after he went to work for the Kennedy administration’s Housing and Home Finance Agency in 1962-63, he continued to consider himself a radical. But if, as his longtime friend Irving Kristol put it, a neoconservative is a liberal who has been mugged by reality, then Mr. Glazer got hit over the head.

He had taken a teaching post at Berkeley in 1963, just as the student rebellions of the 1960s were erupting. Opposed to the growing American military involvement in Vietnam and supportive of social policies designed to help the poor, he initially sympathized with the student protesters. But as they grew more extreme — “nihilistic” was Mr. Glazer’s word — he turned away from them and his own leftist past as well. He moved toward what he saw as a hard-won pragmatism but what others saw as a reactive conservatism.