This article is a contribution to the characterization of teacher-pupil interactions during scientific inquiry. Attention is paid to conclusion phases, as it is at this point in the interaction that a pupil's production is to be accepted or rejected. Sixteen sessions taught by eight teachers in junior high and high schools were recorded, transcribed and analysed. In interpreting the teacher-pupil interactions, the presence of hidden epistemological and pedagogical beliefs in the conclusion phases have been discerned. The conclusion phase corresponds to a dogmatic (vs. constructivist) view of science and the teaching of science if the pupil's production is judged for its veracity in relation to the teacher's scientific knowledge (vs. its validity in relation to knowledge shared by both pupil and teacher). A discussion follows on the conditions for the teacher's building a relationship between this aspect of his practice and his beliefs. The impact of this research on teacher training is also considered.