ABSTRACT Not until the twentieth century did science come to be regarded as fundamentally technical in nature. A technical field, after all, meant not just a difficult one, but one relying on concepts and vocabulary that matter only to specialists. The alternative, to identify science with an ideal of public reason, attained its peak of influence in the late nineteenth century. While the scale and applicability of science advanced enormously after 1900, scientists have more and more preferred the detached objectivity of service to bureaucratic experts over the cultivation of an engaged public. This reshaping of science, which has been both celebrated and condemned, provided a stimulus to the incipient field of history of science, and it remains a key historical problem.