Retying the knot : four articles on science and expertise in a polarized world

While science remains highly valued in our contemporary societies, expertise is increasingly being contested. This contestation is part of long-term trends: the growing role of experts in public decision-making, the expansion of higher education, the rise of the internet and social media, and the intensification of political polarization. These transformations have contributed to changing the way the public engages with expertise. Moving beyond the knowledge-deficit model and a pro-/anti-science dichotomy, this thesis examines the determinants of how experts and their claims are perceived, and the dissemination of this expertise online. In particular, it examines the role of political preferences, expert sources, the mechanism of motivated reasoning, and certain individual assumptions. The thesis comprises four chapters combining experimental data, national surveys, and social media data. The results show that political preferences play a role in the evaluation of expertise. Expert sources enhance the perceived accuracy of claims but can also facilitate the spread of misinformation. Among Europeans, motivated reasoning may play a role in challenging regulatory science. Finally, the intention to share expert information is driven more by the validation of expectations than by the confirmation of beliefs. The results suggest that the ``crisis of expertise'' may have less to do with science than with how authority and expert claims are evaluated and mobilized in our contemporary societies.