Logic and Epistemology in Safety Cases

A safety case must resolve concerns of two different kinds: how complete and accurate is our knowledge about aspects of the system (e.g., its requirements, environment, implementation, hazards) and how accurate is our reasoning about the design of the system, given our knowledge. The first of these is a form of epistemology and requires human experience and insight, but the second can, in principle, be reduced to logic and then checked and automated using the technology of formal methods. We propose that reducing epistemic doubt is the main challenge in safety cases, and discuss ways in which this might be achieved.