Question One: On Promise

477. Promise is presupposed to all other contracts, and is included in all; yet it can be standing by itself, and then it is a simple promise. This is defined: a liberal, deliberate, and spontaneous obligation of faith made to another and accepted, concerning a licit and possible thing to be furnished in favor of another. It is said:

1. liberal, so that it may be distinguished from a mutual and onerous promise which can enter a bilateral and onerous contract, by which namely someone promises and obliges himself to furnish something, if the other undertakes an obligation or burden;

2. deliberate and spontaneous, i.e., perfectly immune from every error, deceit, fear, and force, as befits a gratuitous contract which ought to proceed from mere liberality and accordingly requires full liberty; although this ought not to be verified under the same title in a mutual onerous promise;

3. obligation: thus it is distinguished from a mere intention, which does not include a new obligation toward another; whence he who does not keep an intention without reason is guilty of inconstancy toward himself, but offends neither fidelity nor justice toward another;

4. of faith: thus it is distinguished from donation, which is not the giving of faith but of a thing, in which the thing itself is given, whereas in promise faith is given and an obligation is undertaken of furnishing the thing in the future. Namely, donation gives a right in a thing; not so promise, which at most grants a right to a thing;

5. made to another and accepted by him: namely, it is necessary that the promise be externally manifested and accepted by the promisee; otherwise there would not be a consent of several wills into the same thing, nor a contract. For some sort of right to my obligation cannot arise in another unless the other wills it; whence acceptance is required, which must be made by an external deed, even tacitly if the promise is made to one present and silent, in which case acceptance is presumed;

6. concerning a licit and possible thing...; otherwise the promise would be invalid.

Therefore three conditions are required for promise: 1) the mind of obligating oneself, 2) deliberate and spontaneous will, 3) manifestation of the will and acceptance by the other.

478. Obligation of promise.

1. A gratuitous and unilateral promise of itself seems to oblige only from fidelity, by which man in association with others ought to conform deeds to words; St. Thomas saying, II-II, q. 88, a. 3, ad 1: "according to honesty (which is a moral debt, not a legal one), from any promise man is obligated to man"; nevertheless per accidens it can oblige from justice, if there accedes to it an intention of obligating oneself from strict debt, in which case in the other there arises a true right to the thing. For since a contract is a particular law which the one promising freely imposes upon himself, he can also impose upon himself an obligation from justice. In this case, not in the former, it is a true contract.

2. A bilateral and onerous promise, made under the condition that the other undertake an obligation or sustain a burden for obtaining the thing promised, of itself obliges from justice, and therefore under grave matter from its genus: for it is a perfect or onerous contract. For an onerous obligation mutually undertaken between equals is connaturally of justice, and is wont to be so understood and assumed. Yet it does not seem altogether impossible that two should exceptionally intend to oblige themselves only from fidelity; but this is not to be presumed, but must be proved.

3. An obligation of mere fidelity, even in grave matter, is of itself light; per accidens a grave obligation of justice can accede, by reason of damage that will follow from violation of the promise, for example, if someone promises to give a loan and the promisee therefore does not provide for himself from elsewhere, or if a physician has promised to help a sick man and this man, relying on such a promise, has called no other physician, or if a brother has promised his brother to pay half the expenses for the education of a nephew if he enters college, or if someone has not kept a promised secret: but then the obligation does not arise from contract, but from this, that someone does not remove a voluntary cause of damage.

4. An obligation of justice, when it is had, is grave from its genus; yet for mortal sin a greater quantity is required than in theft. St. Alphonsus after others establishes matter four times greater than that which is required for grave theft relatively to the promisee. This is consonant with reason, because he has only a right to the thing, not in the thing, and a right toward a person who promises altogether gratuitously.

479. The obligation of promise ceases:

1. if the promisee renounces his right or spontaneously condones;

2. if the handing over of the promised thing becomes impossible, or illicit, or useless or damaging to the promisee;

3. if a notable change of circumstances supervenes or becomes known, such that prudently someone would not be judged to have willed to oblige himself for such an event: for an act does not oblige beyond the intention of the one promising;

4. in the case of a mutual promise: if the other has not stood by his promises, because faith is not to be kept with one breaking faith.

If the promisee dies before execution, the one promising is held to nothing, unless it is certain that the promise was made solely or principally with a view to the family of the promisee or his heirs. - If the one promising dies, a personal promise does not pass to the heirs, but is extinguished; a real one passes, unless from the circumstances it is manifest that the one promising willed to oblige only himself personally.

480. Practical observations. - 1. Simple promises, as they are more often made among men, oblige from mere fidelity and not from justice. Those promising sufficiently rarely understand themselves to be obliged from justice. Therefore, unless the contrary is certain, it must be judged that the obligation is not from justice.

2. Indeed those things which according to the external form seem promises, often are nothing but intentions, because the word to promise, in the intention of the one pronouncing it, does not always signify an obligation.

3. An obligation of justice is present when the one promising intends to transfer a true right, and the promisee believes that a right has thereby been acquired by him. This can be certain not only from the express declaration of the one promising, but also from various circumstances, as if he has obliged himself as much as he can, with an oath added, or by a written bond or another written instrument, before witnesses called for this, or before a notary with solemnity, or from common estimation.

4. On account of a promise it is not licit to compensate oneself secretly, unless it is certain that it is not a mere intention but a true promise, and indeed one obliging from justice. This can happen if it was made because of unusual services furnished, in which case a title of wage intervenes (an implicit contract). But even then the mere intention of giving expressed is not to be confused with a true promise; and the sentence of a judge in this question would have force of itself.