The Problem of the Missing Model

Abstract Missing-model problems are a type of problem that arises when scientists are trying to gain access to initially inaccessible phenomena. This paper describes what missing-model problems are, and examines examples of them from seismology, optics, and the theory of gases. It is argued that the examination of missing-model problems will give us a better understanding of the challenges scientists face when attempting to gain access. Two themes for the further study of missing-model problems are laid out: justification and representation.