Assessing student interactions during socio-scientific debates requires an interdisciplinary theoretical background involving linguistics, argumentation, and collaborative learning. Such controversies involve techno-scientific knowledge, but also values and emotions and therefore there is no one correct answer. In this paper we revisit three types of talk (exploratory, disputational, and cumulative) used to assess the quality of students' argumentation in small groups. Authors have mainly used this typology in a mutually exclusive way in problem-solving contexts and our contribution is to show how the three intertwine in authentic interactions, focusing on the construction of complex dialogic arguments. We argue that group talk is a dynamic construct resulting from individuals unceasingly adjusting to each other. We thus propose a theoretical interpretation of how group talk is shaped by and reciprocally shapes individual communicative behaviour, through a process of (non)alignment where self-identity footings are imbricated with face-work within either the ordinary or argumentative politeness system.