ABSTRACT
This chapter argues that the way in which economists use the term ‘equilibrium’ has to be understood in the context of problem solving. Concepts of equilibrium are used in a pragmatic way to solve problems, which often means that rigour is sacrificed to usability. Whether or not a particular situation is or is not an equilibrium may depend on the choices made by the modeller and is not necessarily of any ontological significance. Economic models should therefore be evaluated solely in terms of their problem-solving ability.
