(d) By reason of its manner, a vow is either absolute (e.g., an unconditional vow of chastity) or conditional (e.g., a vow to go on pilgrimage, if one recovers one’s health; a vow to enter religion, if parents consent). A conditional vow is either non-penal, as in the example just given, or penal, in which the promise is that one shall undergo a penalty if fault is committed (e.g., a vow to say the Rosary every time one uses profane language, to fast every time one becomes intoxicated, to give alms every time one is dishonest).
(e) By reason of its form a vow is either express (i.e., externally manifested by words or other signs) or tacit (i.e., externally assumed by reason of some office to which it is annexed, as when one takes the subdiaconate in the Latin Church, to which is attached the duty of celibacy. (It must be noted, however, that some authors consider celibacy arising from the subdiaconate as a duty arising from ecclesiastical law and not from a vow.) The express vow in turn is explicit (i.e., manifested by signs that immediately express the vow, as when the vower mentions poverty and chastity) or implicit (i.e., manifested by signs that express another vow which includes the implicit vow, as when the vower mentions only obedience according to the rule, but the rule includes the other two vows of poverty and chastity). An explicit vow is either determinate (i.e., one in which the thing promised is definitely indicated, as when one vows a pilgrimage) or disjunctive (i.e., one in which the vower promises to perform at his will one or more out of a number of things indicated, as when he vows either to make a pilgrimage or to perform a fast).
(f) By reason of its position before the Church, a vow is either private (i.e., one made without the intervention or acceptance of the Church, as when a person in danger of shipwreck makes a vow for his safety) or public (i.e., one made before the Church and accepted in its name by an ecclesiastical superior, as in the essential vows made in approved Orders or Congregations). The public vow is either simple or solemn, according as the Church has determined for different religious institutes.
2193. Vows in Canon Law.—The canonical dispositions in reference to vows in general will be found in Canons 1307-1315, while religious vows are treated in the section on religious (Canons 492 sqq.), and the effects of vows on matrimony are declared in Canons 1072, 1073, 1058. A fuller treatment of the canonical aspects of vows than can be given here will be found in commentaries on these parts of the Code.
2194. Distinction between Solemn and Simple Vows.—Is the distinction between a solemn and a simple vow one of divine or one of ecclesiastical law?
(a) As to accidental solemnity (i.e., the conditions of time, place, age, fitness, rubrics, etc.), the solemn vow depends on the Church, for there is no doubt that the Church has the right to determine these matters as circumstances may require. Hence, the Church may appoint conditions for the validity of a solemn vow, and she may also change these conditions as she sees fit.
(b) As to the essential solemnity (i.e., the internal characteristic that distinguishes the solemn from other vows), the solemn vow depends, not on the law of the Church, but on the divine law, since, unlike other vows, it is not a mere promise of acts, but an irrevocable giving over to God of one’s person itself and an internal spiritual consecration or espousals accepted by the Church. This is denied, however, by some authorities, who place the difference between the solemn and the simple vow in the different juridical effects which they produce in Canon Law, the solemn vow making acts opposed to it invalid and the simple vow rendering opposed acts illicit, but not invalid (see Canon 579). All agree that the Church may for just reasons dispense even in solemn vows.
2195. Knowledge and Deliberation Necessary for Valid Vow.—In the intellect of him who takes a vow there must be such knowledge and deliberation as are required for making an important contract, for he who takes a vow assumes a grave obligation (see 1883). The rule given by many is that the deliberation which suffices for a mortal sin suffices also for a vow, but this does not appear to be exact, since a mortal sin may be committed when there is only a confused perception of the gravity of the sin (see 177).
(a) Thus, a vow is invalidated by substantial ignorance or error (e.g., Titus, thinking his gold watch is brass, vows to give it as an alms; Balbus, thinking that a distant sanctuary is not very far off, vows to make a pilgrimage to it; Claudius, being wrongly informed that his father is sick, makes a vow to go on a pilgrimage for his father’s recovery), but not by ignorance or error that is merely accidental (e.g., Sempronius, thinking that a sanctuary which is four miles away is only three miles distant, vows to go there on pilgrimage, but he would have made the vow, even though he had known the true distance; Caius, intending chiefly to perform an act of religion, and secondarily to visit a friend, vows a pilgrimage to a neighboring town, not being aware that the friend has moved elsewhere). The vows of religion, according to the common opinion, are not invalidated on account of ignorance or error about accidentals, even though the vows would not have been taken had these accidentals been known; for the common good demands that the religious state, like the married state, have stability, and that those who enter it intend to accept all the obligations that go with it.
(b) A vow is invalidated by the absence of full deliberation (e.g., vows made by children who have not the perfect use of reason, by persons who are only half-conscious or who are delirious or laboring under a hysterical delusion or fixed idea, by persons who act on the impulse of the moment without full advertence to the import or force of the vow), but not by the absence of long or studious deliberation (e.g., a vow is valid if one has thought over its meaning and obligation, even though one has done this hurriedly and without reflection on the details and has regretted the vow soon after its pronouncement).