This paper (in press, Advances in Pol. Psych.) examines the science-of-science-communication measurement problem. In its simplest form, the problem reflects the use of externally invalid measures of the dynamics that generate cultural conflict over risk and other policy-relevant facts. But at a more fundamental level, the science-of-science-communication measurement problem inheres in the phenomena being measured themselves. The “beliefs” individuals form about a societal risk such as climate change are not of a piece; rather they reflect the distinct clusters of inferences that individuals draw as they engage information for two distinct ends: to gain access to the collective knowledge furnished by science, and to enjoy the sense of identity enabled by membership in a community defined by particular cultural commitments. The paper shows how appropriately designed “science comprehension” tests — one general, and one specific to climate change — can be used to measure individuals’ reasoning proficiency as collective-knowledge acquirers independently of their reasoning proficiency as cultural-identity protectors. Doing so reveals that there is in fact little disagreement among culturally diverse citizens on what science knows about climate change. The source of the climate-change controversy and like disputes is the contamination of education and politics with forms of cultural status competition that make it impossible for diverse citizens to express their reason as both collective-knowledge acquirers and cultural-identity protectors at the same time.