(a) There is a dependence of the will of the subject, as in the case of religious who have vowed obedience to their rule and superiors, and in the case of those who have not attained the age of puberty and who must be guided and ruled by their father or guardian. This dependence means, not that the subject must have the positive consent of the superior for every act, but that he must not will or do anything contrary to the just will of the superior.
(b) There is a dependence of the matter of the vow, when it is subject to the wishes of another person, as happens in the case of those who have obligations to others. Thus, a wife cannot make a vow of chastity without the consent of her husband, otherwise she infringes upon conjugal rights; a servant cannot make a vow to spend in visiting churches time for which he is paid; a son who lives with his parents and is not emancipated cannot vow to give his earnings in alms, for he owes them to his family.
2225. The Validity of Vows Made by Subjects.—(a) If the vow is against the rights of another person, it is invalid without his consent. Thus, if a wife makes a vow of chastity without her husband’s consent, the vow obliges her to ask his consent, but it has no force if he refuses his consent.
(b) If the vow is against the subjection due another, it is invalid if he denies his consent. Thus, if a religious vows an act for which according to his rule permission must be sought, the vow has no actual force until the permission is obtained; if he vows an act that is good in itself, but absolutely forbidden in his rule (e.g., if a novice bound to remain in the cloister vowed to go on a pilgrimage), the vow is null, since it is better to keep the rule.
(c) If the vow is neither against the right of another nor against the subjection due, it seems that the vow is valid without the knowledge and consent of the superior. Thus, if a religious privately vows to do what is commanded in a particular law or rule, or what is counselled by his superiors, or what is good and not forbidden, the vow is valid until annulled by the superior; for, as was said in the previous paragraph, the subject is not bound to have the positive consent of his superior for all acts, and it is supposed now that the thing vowed is not detrimental to the rights of the superior or others.
2226. Cessation of Vows.—Since a vow is a private law, it may cease, just as a law ceases in certain cases (see 500 sqq.). There are, therefore, two ways in which a vow ceases or ceases to oblige.
(a) The vow ceases from within, or from internal causes, when the matter of the vow has so changed as to be detrimental or useless, or the purpose of the vow is no longer served by the vow. For the nature of a vow is that it promotes a better good to the greater glory of God. It is clear also that a temporary vow ceases when the time limit fixed to it has expired, and that a conditional vow ceases if the condition is not fulfilled (e.g., one vows an alms of thanksgiving if one’s mother recovers from sickness, but she dies).
(b) The vow ceases from without, or from external causes, when it is removed or suspended by the authority of God to whom it was made (dispensation) or by the authority of one who has power over the will of the vower or over the matter of the vow (annulment), or even by the authority of the vower himself in so far as belongs to him the right to substitute some equal or better work for the work vowed (commutation).
2227. Public vows do not cease from intrinsic causes, for this would be productive of many disadvantages to religious communities and to those who take vows in them. The chief cases in which private vows cease for internal reasons are as follows:
(a) They cease on a substantial change in the thing promised, for then the subject-matter has become morally different. There is a substantial change if the matter of the vow has become illicit (e.g., Titus vowed an alms to a beggar, but he learns that the beggar will use the alms to become drunk), or if it has become useless (e.g., Claudius vowed not to visit a certain house on account of the bad language used there, but the guilty parties have now moved away), or if it has become an obstacle to a greater good (e.g., Balbus vowed to go on a pilgrimage, but an epidemic has broken out and it is better for him to remain home and care for the sick), or if it has become impossible (e.g., Sempronius vowed to give an alms, but lost his money and cannot afford to keep the promise). Some also think there is a substantial change when circumstances are so different that, had the vower been able to foresee them, he would not have taken the vow.