§ III. On Commutation of Vows

Commutation of a vow is the substitution of some work in place of the one promised. It can be made in three ways, namely into a better good, into an equal good, into a lesser good.

I Say 1st. Whoever has the power, even simply delegated, of dispensing from vows has by that very fact the faculty of commuting them; for he who can do the greater can also do the lesser in the same genus. - Cf. St. Alphonsus, n. 246.

I Say 2nd. A priest delegated for merely commuting vows cannot commute them into a notably lesser work, because otherwise he would in great part dispense, and thus would exceed the faculty received. It is said notably, because the faculty of commuting vows is not to be interpreted so strictly that it is confined to an entirely equal work, but is to be taken in a broader sense, so that it extends itself to a work somewhat lesser; for otherwise it would be liable to innumerable difficulties and scruples, since it is most difficult to find equality in things altogether disparate. Moreover, commutation ought to be made for the alleviation of him who has bound himself by vow. - Cf. St. Alphonsus, n. 247.

I Say 3rd. He who emitted a vow cannot commute it into a lesser good by his own authority; for he ought to give to God whatever he promised. Nevertheless, even without a special cause, he can commute his vow into a work evidently better, because while someone performs a work more perfect than the thing promised, by that very fact he observes what he had promised, since the perfect is included in the more perfect. It is also clear from canon law, cap. 3, de Jurejurando. - But in this matter that work is judged better which conduces to the greater spiritual utility of the one vowing and to greater service of God. Yet except vows reserved to the Pope, unless the change is made into the religious state. - Cf. St. Alphonsus, n. 243.

Thus canon 1314: The work promised by a non-reserved vow can be commuted into a better or equal good by the one vowing himself; but into a lesser good by him to whom there belongs the power of dispensing according to the norm of can. 1313.

Question 1. Is some cause required for a vow to be commuted into an equal work, or one a little lesser?

Response. Affirmatively, as regards liceity, because otherwise a delegate would commute prodigally, and would abuse the power of commuting. But as regards validity, the opinion denying this is called probable by St. Alphonsus. - Cf. St. Alphonsus, n. 245.

Question 2. Once commutation has been made, is it licit to return to the first work?

Response. Affirmatively, if the commutation was made into a lesser or equal work, because the first work is equally pleasing to God; indeed even if it was made into a better work, because commutation is made in favor of the one vowing. - Cf. St. Alphonsus, n. 248.

Question 3. Must you return to the first work if the second becomes impossible?

Response. Negatively, if the change was made by the authority of another, even if by your fault it became impossible, because the prior obligation has been dissolved by the commutation itself. But otherwise if you made the commutation by your own choice, because then the prior obligation is not dissolved, but is only supposed to be supplied by an equal or better one. - Cf. St. Alphonsus, n. 249.

Question 4. When a reserved vow has been commuted, does the substituted matter also remain reserved?

Response. Negatively, more probably, because that matter which is substituted is not reserved of itself, although it has the same bond of vow. - St. Alphonsus, n. 260, and others commonly.