This article critically examines the discourse around the Covid-19 pandemic to investigate the widespread polarisation evident in social media debates. The model of epidemic psychology holds that initial adverse reactions to a new disease spread through linguistic interaction. The main argument is that the mediation of the pandemic through social media has fomented the effects of epidemic psychology in the reaction to the Covid-19 pandemic by providing continued access to commentary and linguistic interaction. This social interaction in the absence of any knowledge on the new disease can be seen as a discourse of knowledge production, conducted largely on social media. This view, coupled with a critical approach to the power relations inherent in all processes of knowledge production, provides an approach to understanding the dynamics of polarisation, which is, arguably, issue-related and not along common ideological lines of left and right. The paper critiques two discursive structures of exclusion, the terms science and conspiracy theory, which have characterised the knowledge production discourse of the Covid-19 pandemic on social media. As strategies of dialogic contraction, they are based on a hegemonic view of knowledge production and on the simplistic assumption of an emancipated position outside ideology. Such an approach, though well-intentioned, may ultimately undermine social movements of knowledge production and thus threaten the very values it aims to protect. Instead, the paper proposes a Foucauldian approach that problematises truth claims and scientificity as always ideological and that is aware of power as inherent to all knowledge production.