Article — Noldin, Summa of Moral Theology
Article First. On Promise
546. Its nature. 1. Promise signifies a contract by which someone gratuitously obligates himself toward another to doing or omitting something.
a. Promise must first be distinguished from purpose: for one proposing does not intend to assume some new obligation, but one promising intends to bind himself by a new obligation.
b. He who promises something is called the promiser, but he to whom something is promised is called the promisee.
c. Here there is question of a promise which is made to man, not of a promise which is made to God. But a promise which is made to man is either simple or mutual. Promise, whether simple or mutual, of entering a contract is accustomed to precede onerous contracts, especially real contracts, for example, a promise of giving a loan for consumption, of buying and selling a house, of entering marriage. In this place there is speech of simple promise.
- In order that a promise have force, the conditions are required which are necessary for the value of a gratuitous contract: a. that the will of obligating oneself be present, which he who seriously wishes to promise is considered to have implicitly, even if he does not advert to the obligation; b. that the promise be externally manifested and accepted; wherefore the promiser before acceptance can always still revoke the promise made by natural law.
547. Its obligation. 1. It depends on the intention of the promiser whether the promise obliges from fidelity or from justice.
a. If the promiser intends to obligate himself only from fidelity, he is indeed bound in conscience to fulfill the promise, but only under light obligation, even in a thing of great moment, because fidelity of itself does not oblige under grave obligation; but per accidens, by reason of grave damage which is foreseen to arise for the promisee, it can oblige even under grave obligation.
b. If the promiser intends to obligate himself from justice, he is bound to fulfill the obligation under grave obligation in grave matter. Yet for constituting a grave sin matter four times greater is required than in theft, because not to give one's own thing promised to another is much less opposed to justice than to take away or retain another's thing.1
c. If doubt exists concerning the obligation of the promise, one must stand for the minimum, because an obligation about which there is no certainty must not be imposed. Hence if someone makes a promise in a grave matter, not attending whether he obligates himself under grave or under light obligation, he must be considered obligated only under light obligation.
d. Obligatory promises ordinarily do not oblige from justice, because those promising rarely have the intention of obligating themselves so strictly. But he is considered to obligate himself from justice (and in the external forum is presumed so to obligate himself) who promises with some solemnity, for example, under oath, or adds a written note to the promise, or makes the promise before witnesses.
e. Between the obligation of fidelity and of justice this distinction intervenes: that the obligation of fidelity gives the promisee no right in the thing promised, but obliges only because everyone is bound to conform his deeds to his promises; but the obligation of justice gives the promisee a right to receiving the thing promised, so that from strict right what was promised is owed to him. Yet it does not give a real right in the thing promised, but only a personal right against the promiser or his heirs; therefore it is not licit for the promisee secretly to seize the thing promised for himself.2
A promise even obliging from justice ceases: a. if, after the promise has been made, a notable change of things becomes known or supervenes, which, if it had been known or foreseen before the promise, would have impeded it: for any gratuitous promise is considered made under this tacit condition: if it can be fulfilled without grave inconvenience; b. if before execution the motive cause of the promise ceases, by which the promiser was truly moved either uniquely or principally to promising; c. if the thing promised without fault of the promiser has become impossible, illicit, or useless to the promisee.
Whether a promise must be fulfilled if before execution the promisee dies depends on the intention of the promiser: if the promiser intended either uniquely or primarily the person of the promisee, the obligation ceases, because when he is dead the motive cause of the promise ceases; but if he chiefly intended the family or heirs of the promisee, the obligation does not expire.
If before execution the promiser dies, a real promise passes to the heirs, unless it is established that the promiser wished to obligate himself alone; a personal promise does not pass to them (n. 210, 3).
1 Cf. St. Alphonsus, n. 720.
2 Cf. Lugo, disp. 23, n. 12 ss.