This paper analyses the role of credibility in knowledge dissemination through social networks, focusing on how the felicitous performance of verdictive speech acts, which involves the speakers’ cognitive mastery of the topic dealt with, may give rise to knowledge-disseminating effects in an online communicative context. In particular, on the basis of a corpus consisting of comments on Facebook posts concerning controversial health- or socioeconomic-related issues, we examine how Facebook users manage to achieve credibility either by providing indication of their informative reliability and reasoning capacity or by getting these accommodated, what are the effects of the credibility thus achieved in terms of knowledge dissemination, and how their credibility is challenged by other users, nullifying the knowledge-disseminating effect of their verdictive speech acts.
