ABSTRACT
Among the basic elements in any legal system is the idea of obligation, that is, conduct owed to one or more ascertained persons. Promissory obligation is conduct owed as a result of a promise, and contractual obligation is promissory obligation enforced by law. The classical liberals of the Victorian era developed an attachment to the “will theory,” according to which contractual obligation is the product entirely of the human will. The will theory is not without explanatory force and remains influential, but it fails to fully explain contractual obligation. Because humans are social beings, we cannot achieve our highest good of full human flourishing without cooperative action. It is this necessity of cooperative action in support of reasonable goals that is the true source of all obligation. Promise-making is a practice that can secure such action. Once the promisee expressly or impliedly accepts the promise, or reasonably and foreseeably places hope in its fulfilment, the promisor is obliged to honor it. Contract law strengthens the trust that certain promises will be honored where trust might otherwise be weak, thereby serving the common good. Contractual obligation is the product of will directed by practical reason toward the attainment of reasonable goals, in circumstances where the common good is served by legal enforcement.
