Public trust in science and expertise remains a contentious issue. When public trust is analysed, it often simplifies a complex process of information retrieval and interpretation. Questionnaire surveys help us make sense of differences among actors and countries, but they fail to provide a comprehensive analysis of the reasons that lead citizens to trust a specific actor to differing degrees. Hence, we opted for using a qualitative grounded approach to understand how citizens make sense of their trust in several actors. This article draws from the results of public consultations with citizens in Portugal and Poland about two specific science-related topics-climate change and vaccines-focusing on citizens' perceptions of trust in several sources of scientific information. The results show that citizens' trust varies depending on the source of scientific information, and it is affected by the topic's visibility and different national levels of institutional trust. It also concludes that citizens use different criteria to evaluate trustworthiness and that this process leads to different ways of expressing trust/mistrust: unquestioned confidence, justified trust, reflexive trust, and active distrust. Such knowledge leads to a more in depth understanding of how trust in science is constructed, which can help science communicators and educators choose sources and materials.
© The Author(s), under exclusive licence to Springer Nature B.V. 2021.