Frank Knight was one of the twentieth century’s most illustrious economic thinkers. His writings and enquiry into the nature of method, theory and knowledge in relation to the activities of social actors, and under what circumstances and with what limitations we might adequately theorise social agency, bequeathed a rich tradition of theoretical and practical insight. Many of his writings centred on the issue of risk and uncertainty, how social actors anticipate the future and manage and mediate terrains of uncertainty and risk, and in doing so change the outcomes that obtain. Knight’s contributions essentially constructed a means for assessing and measuring risk in various facets of social activity, seeding insights which remain pertinent today. As the article notes, however, despite Knight’s insights and the methodological schema he constructed for probability analysis, remarkably few social sciences – including international relations – have mined his work. Ironically, much that we need to know to more effectively theorise and accommodate the conundrums of risk and uncertainty into social scientific methods Knight long ago handed down to us.