Long-standing research on disaster risk has tended to focus on physical science and directly connected and observable cause and effect between hazard and impact. More recently, work has extended into questions of complex causation and social construction, where cause and effect are disarticulated over space and time and coloured by an observer’s viewpoint and perception. This has drawn in multidisciplinary and interdisciplinary approaches, including recognition of local or traditional knowledge. The chapter explores this transition and the ways in which the search for a more complete understanding of risk production and human action has brought both increased understanding and greater uncertainty to those who seek to use science for action. By drawing together viewpoints from social and physical science perspectives the chapter identifies four fundamental properties of knowledge production in the context of disaster risk and international development: (1) uncertainty is prevalent throughout disaster research; (2) as knowledge has grown, so awareness of the uncertainties that constrain this knowledge has also grown; (3) uncertainties are likely to remain into the future and so must be embraced; and (4) managing the presentation of uncertainty is a challenge for scientists working with policy-makers and the public, who look to science to reduce uncertainty.