Promise, Moral Obligation of a
PROMISE, MORAL OBLIGATION OF A
A promise is an assurance one gives that he will do, give, or refrain from something to the advantage of another. A promise of some kind is involved in all contracts, but ordinarily when a moral theologian speaks of a simple promise he excludes from consideration mutual or onerous agreements and thinks only of unilateral, gratuitous commitments that an individual may make to the benefit of another.
A promise binds in virtue of commutative justice if it is contractual in the strictest sense of the term, for in that case the promisor intends to obligate himself seriously and the promisee accepts the assurance with that understanding. The deliberate violation of such a promise is therefore gravely sinful, provided that the matter with which it is concerned is not too trivial of its nature to be an object of serious injustice.
More commonly the promises of daily life bind only in fidelity. They involve no strict contract because there is no formal acceptance on the part of the promisee, and the promisor does not intend to put himself under grave moral obligation. The keeping of such promises, therefore, is not a matter of strict justice but is rather a form of truthfulness in which an individual makes his actions conform to his words. Fidelity is a most commendable quality of soul, but it is less urgently necessary to the social good than justice, and its violation under ordinary circumstances is not considered mortally sinful.
A promise, whether binding in justice or fidelity, ceases to oblige (1) if the promisee is willing that it should not be fulfilled, (2) if fulfillment becomes impossible, unlawful, useless, or harmful to the promisee, or (3) if it can be reasonably assumed that the promisor would not have bound himself had he foreseen some supervenient change of circumstance connected with the promise.
When what is promised is morally wrong, the promise is invalid and without binding force from the beginning.
Bibliography: b. h. merkelbach, Summa theologiae maralis, 3 v. (Paris 1949) 2:497–500. d. m. prÜmmer, Manuale theologiae moralis, ed. e. m. mÜnch, 3 v. Freiburg-Barcelona 1955) 2:226–229. h. noldin, Summa theologiae maralis, rev. a. schmitt and g. heinzel, 3 v. (Innsbruck 1961–62) 2:481–482.
[p. k. meagher]