The main paradigm in the study of negotiation is the decision-making approach, which emphasizes an individual-based factor of behavior, self-interest. Focusing on the ultimatum game, we reviewed the segment of the empirical literature that emphasizes social-contextual mechanisms, particularly interpersonal communication and intergroup relations. We found that, through communication, proposals are treated as justifiable claims and that the social context provides different norms for justification. We suggest that aspects of communicative rationality, such as normative rightness and subjective truthfulness, act as organizing principles for approaching negotiation as a joint rule-making process. We argue that any rule proposed is only validated through the agreement of the other side(s) and, thus, the consensualistic approach is better suited for the analysis of negotiation compared to the existing decision-making paradigm.