This article explores strategies in consensus-making processes in international climate diplomacy. Specifically, it examines the consensus-making politics, in the case of negotiating historical responsibility within the UN Framework Convention on Climate Change. In doing so, analytical concepts from the discourse theory of Laclau and Mouffe are utilized to look for rationales that underpin discursive structures as well as agreement. To conclude, three rationales have dealt with conflicts over historical responsibility. While the first rationale hid conflict behind interpretative flexibility, the second reverted to "reasoned consensus," excluding perspectives commonly understood as political rather than scientific. The third rationale has enabled equivocal use of the concept of historical responsibility in several parallel discourses, yet negotiators still stumble on how to synthesize these with a potential to foster future, more policy-detailed, consensuses with higher legitimacy. Understanding the history and current situation of negotiations on historical responsibility from this perspective can help guide policy makers toward decisions that avoid old pitfalls and construct new rationales that generate a higher sense of legitimacy.