Sunk Costs

Decision theorists generally object to “honoring sunk costs” – that is, treating the fact that some cost has been incurred in the past as a reason for action, apart from the consideration of expected consequences. This paper critiques the doctrine that sunk costs should never be honored on three levels. As background, the rationale for the doctrine is explained. Then it is shown that if it is always irrational to honor sunk costs, then other common and uncontroversial practices are also irrational. Second, it is argued that there is no satisfactory way to make a distinction between the two kinds of cases. Third, a proposal is developed which would explain how it could be rational, under certain circumstances, to honor sunk costs.