Abstract
According to an everyday concept of 'argumentation' the presence of authority rules out the possibility for argumentation. However, in the case of appeal to authority, e.g., argumentation and authority coexist. The analysis of teacher-and-student interactions shows that a teacher's utterances are critically evaluated by the students, although these may lack relevant knowledge for adequate evaluation. The teacher cannot rely upon his authority alone; if the students accept what she says, the acceptance can be said to be the positive result of a critical evaluation based on the students' knowledge about the subject. Therefore, a dialogical concept of argument acceptability, related to a conception of a genuine argumentativity of language use, is introduced which 1) states that acceptability is connected to the knowledge/information available to an addressee, and 2) can account for why appeals to authority are accepted as rational arguments.