Political discourse is often dominated by attacks on credibility at the expense of discussions about policy proposals. Such attacks can exacerbate political division and undermine attempts to discuss difficult policy questions in the public sphere. While this is true, it is argued in this article that it is a mistake to simply dismiss all such attacks as irrational and illegitimate deviations from the norms of deliberative argumentation. Resolving questions about whom to trust is vital to our lives as social knowers. Furthermore, the influence enjoyed by speakers (individuals and organizations) is not always warranted and deserves to be challenged. Even though it strains the norms of civility, equality, and inclusion promoted by the deliberative model of democracy, the public contestation of credibility can serve epistemically and socially valuable ends. Thus, the contestation of credibility is a profoundly ambivalent phenomenon. Nonetheless, it has a central role to play in the social rationality of public discourse and merits greater attention by democratic theorists.
Key words: deliberative democracy, trust, credibility, power, ad hominem argumentation.
