Article V. On Commutation

I. Notion. Commutation is the substitution of another honorable work, in place of that which had been promised by vow, under the same obligation (St. Alphonsus, III, 243). It can be made into something lesser, into something equal, and into something better.

II. Required power. Commutation into something lesser requires ecclesiastical power. For it is a partial remission of a divine debt; but remission of a divine debt belongs to the Church alone. Commutation into a better or equal good can be made by the one vowing himself (can. 1314); equality, however, should be taken morally, not mathematically (St. Alphonsus, III, 247).

III. The subject of the power is those who have the power of dispensing in vows (cited canon), according to the saying: He to whom the greater is permitted is surely permitted the lesser. Nevertheless it is not repugnant that only the power of commuting be granted, with the power of dispensing excluded.

IV. Use of the power. Commutation into something better does not require a cause. But commutation into something equal or lesser, in order to be made licitly, requires some cause, though a lesser one than dispensation; likewise commutation into something equal requires a lesser cause than commutation into something lesser. For it to be made into something equal or almost equal, a greater inclination toward it suffices (St. Alphonsus, III, 245).

Commutation into something lesser without a just cause is not only illicit, but also is not valid at least in this sense: insofar as it does not free completely from the debt; hence, supposing its validity, the defect certainly must be supplied. I said supposing its validity, because it is controverted whether or not it is valid in such a way that it suffices to supply the defect. Some affirm, because such a substitution among men is not judged invalid; therefore neither with respect to God, with whom matters are treated even more mildly. Others deny, because a partial dispensation, such as commutation into something lesser is, requires a just cause no less than full dispensation (St. Alphonsus, III, 245).

V. The effect of commutation. 1. After commutation has been made, it remains free to the one vowing to return to the prior matter, unless the commutation was made into a better good and the one vowing has bound himself to it by a new vow. The reason is that commutation has the character of a favor, which the one vowing is not bound to use, according to the saying: that which is granted for someone's favor is not to be turned back to his disadvantage¹ (St. Alphonsus, III, 248).

2. If the substituted matter becomes impossible, the one vowing is not bound to return to the prior matter if the commutation was made by ecclesiastical authority. The reason is that the prior obligation has been removed. Otherwise one must speak if the one vowing himself commuted his vow (St. Alphonsus, III, 249).

3. If a reserved vow has been commuted, the substituted matter does not seem reserved, because reservation regards only the matters designated by law.

¹ Reg. Iur. 61 in VI.