Case 4. A Promise

When Caius, a missionary priest, had recently been transferred to another parish, his former parishioners wished to make a gift as a testimony of their grateful spirit. Titius, one of them, attended a meeting of the parishioners at which this was determined, and, moved after hearing the praises of Caius, promised that he would give five pounds sterling. On the next day, however, because the merits of Caius did not seem so great and the sum of money promised appeared large, Titius changed his mind and determined to give nothing. But because his conscience was not at rest, he disclosed the whole matter in his next confession to Julius, who had succeeded Caius. When questioned by Julius, Titius asserted that he had had no intention of binding himself in justice; hence the confessor began to doubt whether he was constrained under sin by any strict obligation—indeed, not under grave sin because it was not from justice, nor under light sin because, as he said, a light obligation has no proportion with grave matter. Before he gives Titius an answer, Julius asks:

1. What is a promise, and what kind of obligation does it introduce?

2. How does the obligation of a promise cease?

3. Does Julius rightly apply his principles?

4. What is to be said of the case?

1. What is a promise and what sort of obligation does it impose? A promise is a unilateral and gratuitous contract by which one person binds himself to do something for another. The quality of the obligation which a simple promise imposes depends on the intention of the promisor. If he intends to give the promisee a strict right to what he promised, the obligation to fulfil the promise is one of justice; otherwise it will be one of fidelity.¹

1 Manual of Moral Theology, vol. i, p. 496.

2. How does the obligation of a promise cease?

In general a simple promise will cease to bind if some event takes place or becomes known subsequently which would have prevented the promisor from making the promise if it had been known beforehand. A fortiori it will cease to bind if the thing promised become impossible, wrong, or useless, or if anything happen which would suffice to discharge even a bilateral and onerous contract.

3. Does Julius apply his principles correctly?

No; he does not. The doctrine which he applies to this case has reference to the question whether there is an obligation to make restitution when grave harm has been caused by slight negligence. In that case many theologians hold that there is no obligation to make restitution because the unjust act was not perfectly voluntary, and because restitution in such a case has the nature of a penalty, and a grave penalty should not be inflicted for a slight fault. In our case the question concerns the obligation of fidelity which binds under venial sin in great as in small matters.²

2 St. Alphonsus, book iii, no. 552; Lugo, De Justitia, disputation viii, no. 58.

4. The case. Titius has no solid reason for not keeping to his promise, which was made seriously after deliberation about the matter, as we must suppose. He will therefore be bound at least under pain of venial sin to give the five pounds which he promised.³

3 Lugo, De Justitia, disputation xxiii, no. 89.