In this classic article from 2010 in City Journal, the relation between the two is explored.
For the first two-thirds of the twentieth century, American liberals distinguished themselves from conservatives by what Lionel Trilling called “a spiritual orthodoxy of belief in progress.” Liberalism placed its hopes in human perfectibility. Regarding human nature as essentially both beneficent and malleable, liberals, like their socialist cousins, argued that with the aid of science and given the proper social and economic conditions, humanity could free itself from its cramped carapace of greed and distrust and enter a realm of true freedom and happiness. Conservatives, by contrast, clung to a tragic sense of man’s inherent limitations. While acknowledging the benefits of science, they argued that it could never fundamentally reform, let alone transcend, the human condition. Most problems don’t have a solution, the conservatives maintained; rather than attempting Promethean feats, man would do best to find a balanced place in the world.
In the late 1960s, liberals appeared to have the better of the argument. Something approaching the realm of freedom seemed to have arrived. American workers, white and black, achieved hitherto unimagined levels of prosperity. In the nineteenth century, only utopian socialists had imagined that ordinary workers could achieve a degree of leisure; in the 1930s, radicals had insisted that prosperity was unattainable under American capitalism; yet these seemingly unreachable goals were achieved in the two decades after World War II.
Why, then, did American liberalism, starting in the early 1970s, undergo a historic metanoia, dismissing the idea of progress just as progress was being won? Multiple political and economic forces paved liberalism’s path away from its mid-century optimism and toward an aristocratic outlook reminiscent of the Tory Radicalism of nineteenth-century Britain; but one of the most powerful was the rise of the modern environmental movement and its recurrent hysterias.
If one were to pick a point at which liberalism’s extraordinary reversal began, it might be the celebration of the first Earth Day, in April 1970. Some 20 million Americans at 2,000 college campuses and 10,000 elementary and secondary schools took part in what was the largest nationwide demonstration ever held in the United States. The event brought together disparate conservationist, antinuclear, and back-to-the-land groups into what became the church of environmentalism, complete with warnings of hellfire and damnation. Senator Gaylord Nelson of Wisconsin, the founder of Earth Day, invoked “responsible scientists” to warn that “accelerating rates of air pollution could become so serious by the 1980s that many people may be forced on the worst days to wear breathing helmets to survive outdoors. It has also been predicted that in 20 years man will live in domed cities.”
Thanks in part to Earth Day’s minions, progress, as liberals had once understood the term, started to be reviled as reactionary. In its place, Nature was totemized as the basis of the authenticity that technology and affluence had bleached out of existence. It was only by rolling in the mud of primitive practices that modern man could remove the stain of sinful science and materialism. In the words of Joni Mitchell’s celebrated song “Woodstock”: “We are stardust / We are golden / And we got to get ourselves back to the garden.”
Retrieved April 23, 2015 from http://www.city-journal.org/2010/20_3_american-liberalism.html