The Polarization Paradox: Social Media, Young Voters, and the Challenges to the Open Society

The ideal of the open society, grounded in rational deliberation and pluralism, faces growing challenges in the digital age. This study examines how affective polarization—characterized by emotional hostility and antagonism across political identities—and populist sentiments among young Portuguese voters (ages 18–21) reshape democratic discourse, with a focus on the role of social media platforms. Based on a sample of 130 first-time voters in the April 2024 legislative elections, the results show that individuals with populist attitudes are 27% more likely to exhibit affective polarization. Moreover, support for radical right narratives is associated with a 27.6% increase in polarization. Notably, X (formerly Twitter) is associated with higher levels of affective polarization than Instagram, highlighting the differential effects of platform architectures. The study provides empirical evidence for the mediating role of digital platforms in fostering discursive fragmentation and ideological antagonism. It contributes to theories of digital democracy and political communication by clarifying how algorithmic environments intensify group-based hostility and undermine the normative foundations of the open society.