Drawing on ethnographic fieldwork (2019-2020) with a collective of natural scientists in Western Siberia, this paper explores my interlocutors’ techniques for discerning truth in a context of high epistemic uncertainty. Many of the scientists adopted a sceptical stance towards claims of global crisis, including the seriousness of anthropogenic climate change and COVID-19 pandemic. Instead of dismissing my interlocutors’ scepticism as indicative of conspiratorial thinking, the paper approaches it as a manifestation of their techniques of discernment in a context where it was considered self-evident that powerful actors could steer knowledge production both in media and science. By evoking the two distinct Russian concepts for truth, the paper suggests that these techniques were illustrative of my interlocutors’ identity as scientists and their orientation to the truths of 'istina' – the immutable laws of nature independent of human cognition – rather than the human affairs of 'pravda'. Overall, the paper argues for the importance of locating such evaluations about scientific phenomena within the broader landscape of epistemic uncertainty in contemporary Russia and for exploring what critical thinking entails for our interlocutors in particular ethnographic settings.