Authoritarian populism and science denialism have thrown the Science and Technology Studies (STS) community into a “moment of post-truth.” As is suggested by this pun on the proverbial saying, a foundational assumption of STS is called into question by post-truth: The “symmetry principle.” It lays down that STS scholars must not discriminate between true and false beliefs among the actors. Symmetrical treatment of all knowledge claims strengthens the weakest actor in a scientific controversy. That those actors deserve the support they get follows from another foundational assumption of STS, namely the reduction of science to politics. According to the “pouvoir = savoir formula”, epistemological marginalisation is identical with political marginalisation. Phenomena associated with post-truth, such as astroturfing, gaslighting, doubt-mongering, etc. tells us differently. It prompts scholars to adopt an asymmetrical stance towards actors’ self-understanding (what used to be called “false class consciousness”). To make sense of the hostility provoked by such a proposition, the chapter delves into the disciplinary history of STS. This disciplinary history underwrites the suspicion that the warnings from leading STS scholars about the return of scientism hides an even more alarming prospect. Namely, that post-truth will put ideology critique-approaches back on the agenda.