The “long 1950s,” once written off as a conservative era, now figure in many histories as the height of American “high modernity,” the apogee of a scientific outlook rooted in instrumental reason. This portrait suggests that the “Enlightenment project” took firm hold of American thought and culture in the early Cold War years, having finally defeated those who sought to yoke scientific rationality to one or another system of moral restraints. Despite nascent movements of opposition, the story goes, a rationalistic, technocratic form of liberalism dominated national life until the left and right mobilized against it in the 1960s.