Contexts in which bullshit (Frankfurt 1986) is rife in public discourse seem to threaten the very possibility of non-defective public argument. I try to understand why that is so. I start by defending a new, non-assertoric account of bullshit which departs from the Frankfurtian approach. In my view, bullshit undermines a prerequisite of all meaningful argument: a common trust that participants will respect the norms governing the practice of arguing. For this reason, prevalent bullshit can cause a sui generis, community-wide form of “illocutionary disablement” (Langton 1993): speakers struggle to make their words count as the speech-acts they intend them to be when engaging in public disputes.