This paper attempts to outline the process and significance of a shift from a positivist to a social and historical understanding of science. From the viewpoint of an adherent to the new perspective, the positivist model appears as an external, philosophers' image of what is natural science, one which takes at face value what its spokesmen, and to a lesser degree what its practitioners say it is. To identify this line of externally addressed philosophy of science and internalist intellectual history, I would mention Bacon, Sarton, Cohen, Popper and the logical positivists generally. Even recent and formidable sociologists of science (Merton, Ben-David) share key elements of the positivist assumption, that positivism is an accurate reflection of scientific practice and that science is intellectually and internally self-determined (autonomous).