Theodore Roszak was the first to put a name to the new world of communitarian experiments, cults, spiritual entrepreneurs and competing new-age psychotherapies of San Francisco and Berkeley in the late 1960s, and his label – "counterculture" – stuck.
A professor of history at California State University, Roszak, who has died aged 77, was no hippy. A sober, happily married man with a young daughter and a career, he was a perceptive observer of the explosive social changes taking place in the US. Something of a leftist, though no admirer of dogma or orthodoxy, Roszak remained a man of good hope who sought, in a writing career that lasted more than four decades, to ride the new waves of social possibility.
In 1968 he edited The Dissenting Academy, a collection of essays attacking the apolitical culture of the humanities in American universities. Roszak deplored the careerism of the academic profession and called for teachers to become politically engaged intellectuals, willing to tell the truth about Vietnam and the cold war.
The Making of a Counter Culture, a finalist for the national book award in 1969, made it clear that Roszak was not merely an anti-war activist. His discussion of youth culture and the gurus of the age, from Herbert Marcuse to Norman O Brown, was cogent and persuasive. The term counterculture, which became a near-universal shorthand for the world of the rebellious young, identified a shift away from social activism towards what Roszak called the politics of consciousness, and to the multiple forms of psychedelia – which he opposed.
For all its energetic incoherence, the counterculture seemed to Roszak to be one of the few sources of opposition to "capitalist desperados" and technocracy. The voices of technocracy spoke in the plausible tongues of efficiency, reform and modernisation, wrapped in the cloak of inevitability. He hated the way technocracy drained the immediacy of struggle from the political process. Roszak was excited by the rejection of science and technological values by the radical young.
By the time he published Where the Wasteland Ends in 1972, he felt that all liberation and revolutionary movements, as well as technocracy, had manifestly failed. "There is a strange, new radicalism abroad," he argued, "which refuses to respect the conventions of secular thought and value." Roszak felt that the next revolution would emerge from the energies of religious renewal. Writing in a language of "ecological foreboding", he was among the early prophets of the ecological crisis.
Growing up in the 1950s in a Catholic family seems to have permanently inoculated Roszak against all varieties of dogmatic theology. He was born in Chicago, where his father worked as a carpenter, but the family moved to Los Angeles, where he attended high school and met his future wife, Betty. He took a bachelor's degree at UCLA, then completed his doctorate in history at Princeton.
Roszak's Unfinished Animal: The Aquarian Frontier and the Evolution of Consciousness (1975) made a plea for a return to a culture of "material simplicity and visionary abundance". He detected in Person/Planet: The Creative Disintegration of Industrial Society (1978) signs of a changed and enhanced ecological consciousness. He coined the term "ecopsychology" in The Voice of the Earth in 1992. "Other therapies," he wrote, "seek to heal the alienation between person and person, person and family, person and society. Ecopsychology seeks to heal the more fundamental alienation between the person and the natural environment."
In The Cult of Information (1986), he raised doubts about the burgeoning world of information technology. Living as close as he did to Silicon Valley, Roszak did not buy the hype. On the other hand, his powers of prophecy were limited. He predicted no "foreseeable future" for the personal computer.
In his 60s, Roszak wrote of the "longevity revolution". There were still grounds for hope, he argued in America the Wise (1998) and The Making of an Elder Culture (2009). America's 80 million or so baby boomers had another chance to change society. He devoted a chapter in the latter book to the replacement of sex in marriage by companionship and caring. "Especially in your older years," he remarked in an interview with Canada's national news weekly, Maclean's Magazine, two years ago, "that four-letter word – 'help' – becomes so important, and you just have to recognise you cannot keep trying to live by an ethic of self-reliance. It's just an illusion."
Roszak published six novels, including Flicker in 1991, deeply immersed in the mythology and eroticism of the early movies. It earned him something of a cult following.
He is survived by Betty, his daughter, Kathryn, and a granddaughter.
• Theodore Roszak, historian and author, born 15 November 1933; died 5 July 2011