The Rationality of Promising

This essay first examines various conceptions of promissory obligation, which suggest a range of possible benefits associated with promising. Theories of temporally extended practical rationality suggest that to obtain benefits of this kind, it may be rational for a promisor to treat his or her promise as binding. The difficulty is that, whatever practical and normative benefits binding promises may have, it will not always be epistemically rational for the promisor to perform. Thus, to the extent that markets rely on binding promises, they rely on an element of irrationality in human decision-making.