Chapter V — How indeterminate vows are to be interpreted

I. A vow can be indeterminate in various ways: namely, 1. as to time — as if you vow a fast, with no day prefixed; or 2. as to quantity — as if you vow alms, with no quantity defined; or 3. as to quality — as if you promise the Church some vessel, without determining whether gold, bronze, or silver; or finally, as to number — as if you vow several things, without determining this one, or that one — which can occur in various ways, of which more below, concerning the indefinite vow. As to time, this has already been discussed above. Now certain general rules must be assigned, according to which the interpretation of vows must be made; then several cases concerning vows indeterminate as to quantity and quality must be resolved. Let this, then, be:

II. A vow is to be interpreted according to the intention of the one vowing; and, if this is not established, it must be interpreted in the more lenient sense — such that, when there is room for prudent presumption, it should be judged more mildly, and in favor of the one vowing: for an obligation is odious, and is therefore to be restricted, saving the propriety of the words, according to the intention of the one vowing, so far as this can be done doubtfully. Nor does it follow from this that, in doubtful matters, the laxer part is to be chosen, but only that, when doubts occur in this matter, judgment is to be made more easily in favor of the liberty possessed. For the rest, if, all things weighed, grave and prudent reasons leave the mind in doubt, then the safer part must always be chosen, as has been said above.

III. Question. Is a vow indefinite both as to quantity and as to quality valid? Response: Before I proceed further, it is worth resolving this difficulty. For what is indefinite both in quantity and in quality cannot be carried into execution. Hence, in the law "Who [bequeaths] wheat," "Who [bequeaths] an island," "Thus have I stipulated," on obligations and on legacies; "Generally," on legacies; a legacy is vitiated on account of the uncertainty of the thing promised. The same, then, must be said of a vow. Wherefore some maintain that a vow of an indeterminate thing, both as to quantity and as to quality, is null.

IV. The common opinion, however, teaches that this vow is valid — since it absolutely concerns something possible, and honorable; and although it cannot be carried into execution under such indifference, this indifference can nonetheless be removed by the one vowing. Thus one who vows entrance into religious life makes a valid vow — since the one vowing can determine this, or that, order. But what quantity, or quality, is then to be defined, must be decided according to the prudent man's judgment, and according to the intention of the one vowing. When the one vowing has fixed absolutely no quantity at all, it will be up to that man's own prudent judgment, and circumstances considered, to determine what he ought reasonably to carry out, so that the matter be fitting and suited to a vow. This opinion is fairly common. It is defended by Suárez (Bk. IV, ch. 7, n. 13, concl. 4), Sánchez (Bk. IV, ch. 13, n. 3 and following), Castropalao (tract. 15, disp. 1, punct. 12, n. 13), Marín (tract. 9, disp. 3, sect. 2, n. 58), and several others. As for what is objected from civil law, it is commonly answered that the aforesaid laws comprehend only civil promises, but by no means spiritual promises and vows, which are not declared null by canon law, but are referred for determination to the prudent judgment of the one vowing, or of some other upright man.

V. A vow is to be restricted according to the nature of the act, or contract, upon which it falls. If the matter, or contract, subject to the vow, is restricted by conditions, restrictions, or limitations, whether by law, custom, or statute, the vow is understood to be equally subject to all these same restrictions — since then the vow is, in a certain way, accessory to the thing promised, which it cannot free from those conditions imposed by legitimate authority. This is a most common rule, taught by Sánchez (Bk. III, ch. 17, n. 13), Lessius (Bk. II, ch. 42, dub. 4, n. 12), Bonacina (disp. 4, q. 1, punct. 4), Prado (ch. 32, q. 7, n. 1), Tamburini (Bk. III, ch. 3, §4), Suárez (Bk. II, on this matter, ch. 32, n. 2), the theologians of Salamanca (tract. 27, punct. 6, §5, n. 149).

VI. A vow obliges, like an oath, so long as the things promised remain in the same state. On the contrary, if the things have changed, the obligation ceases. Since a vow obliges only according to the intention of the one vowing. Whenever, then, such changes occur as, had the one vowing foreseen them before making the vow, he would not, acting prudently, have made the vow — then it must be said that the vow does not bind the one vowing, unless other circumstances suggest the opposite. For in any vow whatsoever a tacit condition is included, unless a notable change should supervene. This rule too is common among the authors cited. Nor does the vow thereby become conditional, but remains absolute; for a vow is called conditional when the condition is not, as it were, inserted into the very nature of the vow itself, but is imposed extrinsically, and freely, by the one vowing. Two things, however, must be observed here. One is that this supervening change, in order to remove the obligation of the vow, must be most grave, and manifest, and must not arise either from the nature of the vow itself, or from the malice of the one vowing. For if the change consisted in some grave difficulty of the one vowing, which, while he was making the vow, he already foresaw; such a grave difficulty, proceeding from the one vowing himself, would not constitute a change removing the obligation of the vow. The other is that a supervening change, when it is not grave and manifest, though it does not remove the obligation of the vow, can nonetheless be a cause for obtaining, more easily, a relaxation of the vow.

VII. When a vow, or oath, redounds to another's detriment, it must be restricted, so that it inflicts no harm on another — since, whenever a vow or oath harms another, it is unlawful, nor can it validly bind by any pact; as is gathered from the chapter "Those who come," dist., "With yours," on the swearing of oaths. If you swore to keep a secret for someone, you need not keep it, when it harms another — as will be said concerning oaths.