Separating the Wheat from the Chaff

Abstract: We study a reputational cheap-talk environment in which a judge, who is privately and imperfectly informed about a state, must choose between two speakers of unknown reliability. Exactly one speaker is an expert who perfectly observes the state, while the other is a quack with no information. Both speakers seek to be selected, while the judge wishes to identify the expert. We show that, quite generally, there is an equilibrium in which the expert is honest, yet the judge favors more extreme signals. This bias toward extremism does not induce exaggeration by the expert, but instead sustains truthful communication. The quack strategically mimics the expert's speech, and sometimes panders to the judge's prior. We show that learning in this environment exhibits an ``information begets information'' property: judges with more precise private information are more likely to identify the expert and learn the true state, implying that exposure to competing sources of uncertain reliability may amplify informational inequality across audiences.