Concurrent Commitment Incompatibility: How Two Promises Can Each Be Kept Until Both Are Due

This conceptual paper introduces Concurrent Commitment Incompatibility, a mechanism in which previously accepted commitments compete for the same time, money, materials, or capacity. Each commitment can remain feasible on its own while the commitments become impossible to satisfy together. The account assesses a broken commitment by examining the joint feasibility of the commitments and responsibility for accepting them together. Incompatibility does not establish dishonesty, and a conflict may arise through an unexpected reduction in capacity or under an understood order of priority. The relevant question is whether the shared constraint could support the commitments in combination. The discussion connects the mechanism to Goode’s theory of role strain and examines United Express Flight 3411 in 2017, when four seated customers were denied boarding so that a crew could reach a later assignment. The case illustrates commitments competing for limited capacity and the later allocation of the resulting shortfall. Part of the Coordination and Dependence series within On Human Modeling, the paper examines how separately feasible promises become jointly incompatible and who bears the consequences when capacity is insufficient. Its framework can inform human–AI research on scheduling, multi-request systems, resource allocation, and whether commitments are evaluated jointly before they are accepted.