Lying in persuasion

We study how the speaker acquires information when they can misrepresent it in communication with the audience. In a binary action setup, we characterize the speaker's optimal information design and the parametric conditions under which the acquired information is disclosed truthfully. When the players' preferences are sufficiently misaligned, the speaker uses the same information structure as when they could not lie, and they communicate that information truthfully. By contrast, when the players' preferences are sufficiently aligned, the speaker chooses a different information structure that generates more persuasive beliefs and induces lying in equilibrium. The speaker's loss of welfare due to the lack of commitment power is more pronounced when lies are harder to detect.