(c) The good work may be a work less good, that is, one which is clearly less difficult or meritorious, as when a Mass is commuted into a Rosary.
2240. Persons Who Have Authority to Commute a Vow.—(a) The commutation of a non-reserved vow into something better or equally good may be made by the vower himself, if there are no rights of a third party to forbid this. For the ends of the original vow (viz., the honor of God and the spiritual welfare of the vower) are thus better or at least equally served. But ordinarily one should not commute one’s own vows, since for most persons it is not an easy matter to decide what is a better or an equal good. How many understand the respective rank of the virtues? And even if one does know, for example, that religion is better than temperance, one cannot decide from this alone that a Rosary is an equal or a better substitute for a fast. One who wishes commutation for his vow, therefore, should consult his confessor or another priest.
(b) The commutation of a vow into something less good can be granted only by the one who has a special faculty; for this kind of commutation partakes of the nature of a dispensation, inasmuch as it relaxes to some extent the original vow. Those who have the power of dispensing (e.g., regular confessors who have the privileges of Mendicants) have also the power of commuting; but those who have only the power of commuting may not change a vow into something that is of notably less value. A good rule to follow in commuting a vow into something less is that more frequent reception of the Sacraments be the substitute ordered. The limitations on dispensations by reason of the rights of third parties (see above 2236) apply also to commutations.
2241. The Cause Required for Commutation of a Vow.—(a) For commutation into something better no cause is required, since the new work is its own justification. (b) For commutation into something of equal value, some cause is required, since it is a mark of inconstancy and therefore displeasing to God to give over one’s promises without good reason. But a light reason is sufficient, such as greater devotion or less danger of violating the vow. (c) For commutation into something of less value, a proportionate reason is necessary, not only for lawfulness, but also more probably for validity, since this kind of commutation is a partial dispensation. But the reason need not be so serious as that needed for a full dispensation.
2242. Reversion to Original Vow.—The return to the original vow by one whose vow has been commuted is always lawful, and in certain cases may be obligatory.
(a) It is lawful, even though the vow was commuted into something better; for a commutation is a privilege, and there is no obligation of using a personal privilege (see 523). Some authors hold that this doctrine does not apply when the vower himself commuted his vow into something better, but the common opinion is that the principle of privilege applies to every case, and that one may even choose between different works if a vow has been commuted a number of times. Those who make vows should be on their guard, however, against frequent and needless changes, since inconstancy is harmful spiritually.
(b) The return to the original vow is obligatory according to some when the vower commuted his own vow to something better and the new matter has become impossible; for the effect of the commutation was not to extinguish the old vow at once, but to offer a satisfaction in its place, and hence when this satisfaction proves impossible the vow must be performed. Others deny this and maintain that the old vow is extinguished immediately, since one who commutes a former vow is immediately held under vow to the substituted work. All agree, however, that if the commutation is granted by authority, the old vow is extinguished and there is no duty to return to it if the substituted work becomes impossible, even though the impossibility is due to the vower’s own fault. Hence, if a pilgrimage is commuted into a fast and the vower through his carelessness becomes sick and unable to fast, there is no obligation either to make the pilgrimage or to fast. It should be noted, though, that private vows made before religious profession are suspended only so long as the vower remains in the institute he has joined, and hence, if he is dismissed or leaves, the vows revive (Canon 1315).
2243. Duties of Confessors in Reference to Private Vows.—(a) A confessor should not readily permit penitents to take private vows, since a vow is a serious matter and should receive mature deliberation. A vow taken hastily in a fit of fervor will likely be soon repented of (see 2221). But if it seems that a penitent will be benefited by a vow, the confessor should give permission, though it will frequently be advisable to limit the duration of the vow at first to a month or a year or other fixed period.
(b) Nor should a confessor be easy in recommending commutations of private vows, lest those who have taken them be encouraged to make continual changes. On the other hand, if there is a good reason for a change (such as danger or difficulty in the old matter or greater devotion in the new matter), the confessor should not stand in the way of a commutation. Confessors who have not the faculties must have recourse to authority for dispensations and dispensative commutations, and the same course is advised for some difficult cases of annulment (e.g., when a husband and wife have made a mutual vow of continence).
2244. External Acts of Religion in Honor of God.—We now pass on to consider those external acts of religion in which the worshipper makes use of divine things in order to show honor to God (see 2175). These sacred things are of two classes, namely, objects whose use is the sanctification of man (Sacraments and sacramentals) and words whose use is the power they have on others or the manifestation of reverence towards God (the Divine Name). Sacraments and sacramentals will be dealt with later. For the present we shall speak of the honor shown to God by the use of His Name, and hence we shall take up in turn the following subjects: (a) use of the divine name to confirm before others one’s declarations or promises (oaths); (b) use of the divine name to move others to do or omit something (adjuration); (c) use of the divine name to express praise and invocation.