Major decisions relating to marine-based activities are strongly influenced by levels of community support. Social acceptability is determined by the distribution of opinions on an issue, which can range from strongly aligned (consensus) to strongly polarized (conflict). Where these opinions relate to use of community resources, a positive consensus may imply a “social license to operate”. However, lack of agreed operational definitions for these concepts has hindered theoretical development and limited their application for assessment purposes, while also inviting their appropriation to advance self-interests and other agendas. Here we propose a new theory that quantifies these concepts based on measured community attitudes. We demonstrate the practical application of the theory in relation to support for climate action, support for offshore wind energy, and support for salmon aquaculture.