Breach of Promise

Infidelity and Violation of a Secret.—It remains to speak of the vices of infidelity and violation of secret (see 2388 a). As to the former, since it has been discussed elsewhere (1877 sqq., 1888, 1889; see also the matter on Promissory Oaths), it will suffice here to ask the question: Is the breach of a promise freely given a sin?

(a) If observance of the promise is due from fidelity only, there is no legal fault, but there is moral fault, and hence the breach of the promise is a sin. The malice is essentially the same as that of untruthfulness (see 2395), for both the liar and the promise-breaker show themselves unreliable, the former because his words do not square with his mind and the latter because his deeds do not live up to his plighted word. Breach of promise, then, seems per se to be a venial sin, though there are often circumstances (such as damage done) that make it mortal.

(b) If observance of the promise is not due even from fidelity, on account of the presence of some defect, there is no moral obligation to keep the promise and no sin is committed by not keeping it. The defects referred to are such as make the promise lack force from the beginning (e.g., if it was immoral or extorted by force), or deprive it of the force it had (i.e., inability on the part of the promisor or loss of right on the part of the promisee). The promisor is unable to keep the promise, if the thing promised has become physically impossible (e.g., he no longer has the strength or the means to perform what he promised), or morally impossible (e.g., the thing promised has become unlawful, or a notable change has taken place which, could it have been foreseen, would have prevented the promise). The promisee loses his right if the sole or principal reason that dictated the promise has ceased, or if the promise has become useless to the promisee, or if the promisor has been released, or if the promisee forfeits his claim by his own perfidy towards the promisor (see 2256 sqq., 1889).