Critical publicity and its epistemic challenges A philosophical approach to public opinion formation in a post-digital public sphere

This dissertation asks whether classic ideals of ‘critical publicity’ can still sustain democratic opinion formation in a platform-mediated media system. It argues that, alongside input legitimacy (who participates) and output legitimacy (what policies deliver), we must foreground throughput legitimacy: the quality of the communicative processes through which claims are produced, challenged, revised, and corrected. The emphasis therefore shifts from mere access and outcomes to the deliberative, epistemic, and reflexive functions of public communication - organising controversy, processing information and arguments, and revising problem definitions.
The theoretical chapters revisit Nadia Urbinati and Jürgen Habermas. Urbinati helpfully centres institutional mediation but underestimates deliberative dynamics. Habermas acknowledges epistemic dimensions yet treats process quality as a ‘black box’ outsourced to professional media. In response, the dissertation proposes a revised normative framework that makes throughput explicit and sets criteria for it.
Empirically, three publicity practices are examined. (1) Social-media influencers during the COVID-19 pandemic expanded reach but often acted as mere conduits, lacking throughput legitimacy. (2) Activist interventions - especially around climate change - force epistemic scrutiny and procedural adjustment, thereby enhancing reflexivity. (3) Networked investigative journalism (e.g., ICIJ and Bellingcat), strengthen throughput via transparency, cross-border diversity, and iterative publication that invites correction.
The conclusion argues that, in a fragmented, platformized public sphere, throughput legitimacy is a precondition for democratic opinion formation. Without high-quality processes, publicity degrades into a realm of uncritical amplification, noise and propaganda. With procedural openness, methodological transparency, and participatory but epistemically grounded practices, critical publicity can be renewed and democratic legitimacy sustained.