Fears of a moral hazard effect deterring mitigation have dogged solar radiation management (SRM) research since before 2006. Researchers have debated the significance and relevance of this concern from multiple disciplines and perspectives. This article explores this debate, highlighting the significance of policy goals and the actual and perceived substitutability of SRM for mitigation. The continuing problems in detecting mitigation deterrence in practice are noted. Different forms of moral hazard effect are distinguished, and the plausibility of mitigation galvanization considered. It is predicted that attention will turn to the situated, contingent expressions of mitigation deterrence and mitigation galvanization among different actors and at different scales; and to more sophisticated practical means to minimize the incidence and impacts of mitigation deterrence.