Hayek defined "scientism" or the "scientistic prejudice" as"slavish imitation of the method and language of Science" when applied to the social sciences, history, management, etc. Scientism represents "a mechanical and uncritical application of habits of thought to fields different from those in which they have been formed, and as such is "not an unprejudiced but a very prejudiced approach which, before it has considered its subject, claims to know what is the most appropriate way of investigating it." (Hayek's Economica essays on scientism were collected in his 1952 Counter-Revolution of Science and reprinted in volume 13 of the Collected Works.)
Austin L. Hughes has a thoughtful essay on scientism in the current issue of the New Atlantis (HT: Barry Arrington). Hughes thinks "the reach of scientism exceeds its grasp." The essay is worth a careful read — he misses Hayek but discusses Popper and other important critics. One focus is the "institutional" definition of science, defined with the trite phrase "science is what scientists do." Here's Hughes:
The fundamental problem raised by the identification of “good science” with “institutional science” is that it assumes the practitioners of science to be inherently exempt, at least in the long term, from the corrupting influences that affect all other human practices and institutions. Ladyman, Ross, and Spurrett explicitly state that most human institutions, including “governments, political parties, churches, firms, NGOs, ethnic associations, families ... are hardly epistemically reliable at all.” However, “our grounding assumption is that the specific institutional processes of science have inductively established peculiar epistemic reliability.” This assumption is at best naïve and at worst dangerous. If any human institution is held to be exempt from the petty, self-serving, and corrupting motivations that plague us all, the result will almost inevitably be the creation of a priestly caste demanding adulation and required to answer to no one but itself.