This paper provides a thorough analysis of two often informally stated claims. First, successful argumentation in the sense of persuasive argumentation requires agreement between the interlocutors about the rationality of arguments. Second, a general agreement about rationality of arguments cannot itself be established via argumentation, since such an attempt leads to an infinite meta‐regress. Hence, agreement about the rationality of arguments is a precondition for successful argumentation. As the paper argues, these plausible claims hold under the assumption that interlocutors are (...) subjectively rational and follow their own standards of rationality when engaging in argumentation. (shrink)