The place of science in society is again in question, much as it was when Science & Technology Studies (STS) first emerged to challenge scientism and technocracy. In this graduate seminar, we revisit classic STS texts against the backdrop of today’s crises of expertise—climate skepticism, the replication crisis in psychology, and controversies around psychedelic-assisted therapy, medical freedom, and market approval of new treatments—treating these sites as occasions for a kind of fieldwork in philosophy of science. We will develop a conceptual and methodological toolkit for studying science in practice, drawing on ethnography of expert communities, analysis of scientific controversies, and theoretical arguments about realism, constructionism, and the demarcation of science against other cultural activities. At a point in history when it is no longer self-evident that we are living in a “knowledge society,” the course asks what happens when claims about the social construction of facts are mobilized both to democratize expertise and to undermine it, and how scientists, clinicians, regulators, activists, and citizens negotiate these tensions. The seminar is intended for students in anthropology, sociology, psychology (including those involved in psychedelic-assisted therapy research), environmental policy, philosophy, and anyone who wants to think rigorously and concretely about the role of science in contemporary politics and public life.