Section — Prümmer, Manuale Theologiae Moralis
§ 3. On the Obligation of an Oath
448. Preliminary. In treating of the obligation of an oath, the discourse is principally about a promissory oath. For although an assertory oath, in the very act of swearing, strictly requires and obliges that the truth be spoken, since otherwise the most grave sin of perjury is committed, nevertheless, once an assertory oath has been duly taken, no other obligation remains. Certainly a grave obligation can arise to repair damage caused by a false or unjust assertory oath, but such an obligation arises only accidentally, namely, from the abuse of the oath; and it is not proper to an oath, but common to every unjust action. It remains, therefore, that only the obligation of a promissory oath be treated. This obligation is twofold: 1. the one swearing must, in the act of swearing, have a sincere will to fulfill the things promised; 2. the one swearing must, at the established or opportune time (if no time was established), actually fulfill the things which he promised by oath. In order, we treat: 1. of the obligation itself of a promissory oath; 2. of the interpretation of this obligation; 3. of the cessation of this obligation.
1. Existence of the obligation.
449. Principle. a) A promissory oath clothed with the due conditions binds, from the virtue of religion, only the person swearing to those things which were sworn. b) This obligation is grave or light according to the gravity of the matter promised.
Explanation. a) That a promissory oath clothed with the due conditions binds in conscience is easily proved both from Sacred Scripture and from reason. "Thou shalt perform thy oaths to the Lord."561 "If any man vow a vow to the Lord, or bind himself by an oath, he shall not make his word void, but shall fulfill all that he promised."562 The reason is added: By swearing, a man invokes God as though the guarantor of the execution of the thing promised. But it is a great irreverence inflicted upon God if someone culpably does not keep such a promise, since this is contempt and disparagement of God as witness. An oath, as a personal act causing a personal obligation, binds from the virtue of religion only the person swearing;563 therefore it cannot validly be taken through a proxy, at least in ecclesiastical law.564 Therefore the same things also apply which were said above in n. 402 concerning the obligation of a vow.
One who violates a simple promissory oath commits one sin, namely, irreverence toward God. One who violates a sworn vow commits two sins, namely, a sin of irreverence because the oath is violated, and a sin of infidelity toward God because the vow is violated. For although both the violation of an oath and the violation of a vow are against the same virtue of religion, nevertheless in each there is a specifically diverse malice, since in such an oath the invocation of divine testimony is violated, but in a transgressed vow the fidelity promised to God is violated. One who violates a sworn pact likewise commits two sins: one against religion, the other against justice. Finally, one who violates a vow with a sworn pact commits three sins because of a threefold violation, namely, of the vow, the pact, and the oath.
You ask: Which obligation is more grave (other things being equal), that of a vow or of an oath? Other things being equal, the obligation of a vow seems to be more grave, since it binds from fidelity toward God; but a promissory oath binds rather from reverence toward God as the guarantor invoked. Fidelity, moreover, seems to be a stricter obligation than simple reverence, since every infidelity contains irreverence, but not conversely.565
561 Matt. 5:33.
562 Num. 30:3.
563 S. theol. 2, 2, q. 98, a. 2 ad 4.
564 Cf. Code of Canon Law, c. 1316, § 2.
565 S. theol. 2, 2, q. 89, a. 8.
450. b) The second part of the stated principle is greatly disputed. All indeed teach that it is a grave sin of perjury if someone culpably does not render grave matter promised by oath; but several distinguished authors, such as Cajetan,566 Lessius,567 Valentia,568 and especially Concina,569 think that there is no slightness of matter in the violation of a valid promissory oath, because every violation of an oath is perjury and every perjury is a mortal sin. These authors admonish, however, that they speak only of valid oaths made with serious deliberation, and not of those which are made without serious deliberation or an intention of swearing. Hence even they concede that mothers do not sin mortally who promise children under oath an apple which they nevertheless do not afterwards actually give; on the contrary, they say that he sins mortally who seriously and deliberately swore that he would give one obol and afterwards culpably refuses this obol.
The far more common and more probable opinion admits slightness of matter in the violation of a promissory oath. Certainly, if someone swearing from the beginning did not will to execute the oath even in light matter, there is a mortal sin of perjury, not indeed because of the matter itself to be rendered, but because of a lie confirmed by an oath. But then not only the promissory oath but also the assertory oath is violated; for this man asserts under oath that he wills to give this light matter, and in reality he does not will this. Therefore such a one swearing invokes God as witness to a lie; this is a grave irreverence and consequently a grave sin. But that there is slightness of matter in the violation of a promissory oath is already inferred from the fact that the obligation of a promissory oath is less than the obligation of a vow, as was said above from the Angelic Doctor. But in the violation of a vow there is slightness of matter, as all concede. Therefore, a fortiori, there is slightness of matter in the violation of a promissory oath. Moreover, as St. Thomas570 says, "one who promises something, if he has the intention of doing what he promises, does not lie, because he does not speak contrary to what he bears in mind; but if he does not do what he promises, then he seems to act unfaithfully by this, that he changes his intention." But infidelity certainly admits slightness of matter, so that in a small thing it is not a grave sin. St. Antoninus,571 St. Alphonsus,572 Dominic Soto,573 John of St. Thomas,574 Sylvester Prierias,575 and almost all modern authors576 defend the proposed opinion concerning slightness of matter in a promissory oath as probable or even as more probable.
Hence, if someone swore to observe the statutes of some college, chapter, or University, and afterwards violated some small statute, he sins only venially; if someone swore that he would no longer drink wine, and afterwards took a little, he does not sin gravely. But what is slightness in the violation of a promissory oath? The same things are to be said as were established above in n. 405 for the violation of a vow; indeed, since an oath, other things being equal, does not bind as strictly as a vow, the matter of transgression in it can be increased somewhat before a grave sin is reached.
566 Cajetan (in his Summa, s.v. "promissory oath") simply teaches that every violation of a promissory oath is a mortal sin; this doctrine he mitigates somewhat in his Commentary on 2, 2, q. 89, a. 7.
567 De iust. l. 2, c. 42, dub. 5.
568 In 2, 2, disp. 6, q. 7, punct. 3, concl. 3.
569 In Decal. l. 5, diss. 2, c. 1.
570 S. theol. 2, 2, q. 110, a. 3 ad 5.
571 S. theol. P. 2, tit. 10, c. 4, § 1.
572 Theol. mor. l. 3, n. 173.
573 De iure et iust. l. 8, q. 1, a. 7, dub. 1.
574 In 2, 2, q. 88, disp. 29, a. 8.
575 Summa Summ., s.v. "Iuramentum" 4, q. 1.
576 Cf. Göpfert, Moraltheol. I, 357.
451. Conditions required for inducing an obligation.
The due conditions of a promissory oath for inducing its obligation are similar to the conditions indicated above in n. 392ff. for the validity of a vow; therefore, they are required both on the part of the matter and on the part of the person swearing.
On the part of the matter it is required that the thing promised by oath be: a) possible; b) good and lawful.
Hence an oath is invalid a) concerning an impossible thing, because no one can bind himself to an impossible thing; b) concerning a dishonorable thing, because otherwise a manifest conflict of duties would arise: for by natural law a man is bound to avoid every dishonorable and unlawful act, but by the oath he would have to perform the same act. Hence Rule of Law 58 in VI° says: "An oath taken against good morals is not obligatory."577 c) Concerning an entirely vain and useless thing, because every true oath ought to intend the worship of God. But God cannot be worshiped by entirely vain and useless things.578 Because of inept matter, the oaths of Freemasons, an oath concerning telling a lie, and an oath concerning taking revenge are invalid, for example. The oaths also of parents or masters by which they threaten that they will punish, beat, or cast out their children or servants in such a determinate way are almost always invalid, both because a true intention of swearing is absent and because it is very doubtful whether such an oath concerns apt and useful matter.
577 Cf. also c. 1, II 11 in VI°.
578 Cf. what was said above in n. 400 concerning the matter of a vow.
452. Scholion. On the obligation of an oath of fidelity. A special difficulty can arise concerning the so-called oath of fidelity,579 i.e., an oath of obedience and fidelity which officials, soldiers, and indeed, in certain regions, bishops must take to princes or to the public authority. This oath of fidelity (a legitimate government being supposed) is lawful of itself. If priests or bishops should at any time be compelled to take an oath of this kind, first the concordats in force between the Holy See and the civil power are to be attended to. Then the one swearing neither can nor ought from the virtue of religion to bind himself to observe each and every law, even the unjust laws, of that region, but must always understand the clause: the laws of God and of the Church being preserved. For the rest, the meaning of the oath taken is customarily no other than that the priest or bishop wills to undertake nothing against legitimate civil authority and that he intends faithfully to exercise the office entrusted to him. Officials and soldiers are not bound by force of an oath of fidelity to unlawful things, since no one can bind himself before God to an unlawful thing. A soldier who, after making an oath of fidelity, deserts the army certainly sins, unless, however, a) he was unjustly compelled to military service; b) because of military service he is placed in the most urgent danger of eternal salvation. In our times either case can scarcely ever occur if it concerns laymen destined for military service. For dangers to eternal salvation existing in the army can be guarded against by means other than desertion, e.g., by avoiding evil companions or denouncing them to legitimate authority. A soldier who has already deserted the army in an unlawful manner ought not be compelled by a confessor to return to the army, both a) because the most bitter penalties will be inflicted upon him and therefore the fulfillment of the oath has become morally impossible, b) because so grave a loss is not caused to the commonwealth by the desertion of one or another soldier, and c) because the admonition of the confessor would probably be ineffective.580
579 Diensteid, Amtseid, Fahneneid [oath of service, oath of office, military oath].
580 Cf. above I, n. 301.
453. On the part of the person swearing there are required: a) an intention of swearing; b) sufficient deliberation; c) liberty; d) absence of substantial error.
a) Concerning the intention necessary for the validity of an oath, something has already been said above in n. 441.
b) That deliberation is considered sufficient which is required for a perfectly human act or even for entering an onerous contract. Because of a defect of sufficient deliberation, the oaths of the intoxicated, the demented, the furious, and others lacking the perfect use of reason are invalid.
c) Liberty is required for the validity of an oath, so that an oath extorted by irresistible force or physical violence is altogether invalid.
It was greatly disputed whether an oath made under the influence of grave fear is valid. All indeed agreed that oaths made under the influence of grave fear unjustly inflicted can be rescinded by legitimate authority; likewise, all conceded that one who made an oath from grave fear unjustly inflicted can recover in court the things which he paid because of such an oath. Finally, positive law so establishing, certain oaths made from grave fear are by that fact invalid, e.g., concerning entering betrothals and marriages,581 and concerning making religious profession.582 But apart from these cases, the more common and more probable opinion taught that oaths made from grave fear are valid. Thus teach St. Thomas,583 St. Alphonsus,584 Dominic Soto,585 Billuart,586 Suarez,587 Lugo,588 Göpfert,589 and others. This opinion has now been defined in Code of Canon Law, c. 1317, § 2, which establishes: "An oath extorted by force or grave fear is valid, but can be released by an ecclesiastical superior." On this matter the Angelic Doctor already briefly handed down the whole doctrine:590 "In an oath which someone makes under compulsion there is a twofold obligation: one indeed by which he is bound to the man to whom he promises something; and such an obligation is removed by compulsion, because the one who inflicted the force deserves this, that the promise not be kept to him. But the other is the obligation by which one is bound to God to fulfill that which he promised by His name; and such an obligation is not removed in the forum of conscience, because he ought rather to sustain temporal loss than to violate the oath."
"He can, however, recover in court what he paid; or denounce the matter to the prelate, notwithstanding that he swore the contrary, because such an oath would tend to a worse outcome, for it would be against public justice."
d) Substantial error invalidates an oath in the same way that it invalidates a vow made with such an error; accidental error, however, invalidates neither an oath nor a vow. Cf. what was said above in n. 396 concerning vows made with error.
581 Cf. below in the tract on marriage III, n. 719.
582 C. 1, X 1, 40; Council of Trent, sess. 25, c. 19 de regularibus.
583 S. theol. 2, 2, q. 89, a. 7 ad 3, and q. 98, a. 3 ad 1. Cf. above n. 266.
584 Theol. mor. l. 3, n. 174.
585 De iure et iust. l. 8, q. 1, a. 7.
586 De relig. diss. 5, a. 6, § 3.
587 De relig. tr. 5, l. 2, c. 10, n. 4.
588 De iust. disp. 22, n. 194.
589 Der Eid, 288.
590 S. theol. 2, 2, q. 89, a. 3 ad 3.
454. 2. The interpretation of an oath is to be made according to the following three rules:
First rule. A promissory oath is of strict interpretation.591 The words of an oath are indeed to be understood in their obvious sense; but when a prudent doubt arises, as small an obligation as possible is to be imposed upon the one swearing. The reason is that the one swearing is not considered to have willed to bind himself beyond the strict sense of the words. Nor is it an objection that an oath is to be interpreted in favor of religion, because the more benignly an oath is interpreted, the more rarely it is violated, the more securely it is observed, and the more sacredly religion is preserved.
Second rule. In every promissory oath, however absolutely pronounced, the following conditions and limitations are understood, whether from the nature of the matter, from a provision of positive law, or from custom:
a) "If I shall be able physically and morally, I shall observe the oath." For no one of sound mind wills to bind himself to the impossible.
b) "The right of the superior being preserved." For a subject cannot diminish the right of the superior; but the latter, for a just cause, can release or dispense an oath.
c) "Unless the other remits my obligation, yielding his right."592 For the principal obligation of an oath arises from the promise made. But if the other remits the obligation of the promise, by that very fact he also remits the obligation of the oath. Hence sworn betrothals can be dissolved by free mutual consent.
d) "If circumstances have not been notably changed."593 For a notable change supervening produces, as it were, a new object to which the intention of the one swearing is not presumed to have extended; e.g., if a young man promised a girl marriage under oath, nevertheless he is no longer bound to execute the sworn promise if the girl has committed fornication or has fallen into a grave and incurable disease. For the rest, the things which we said above in n. 410 concerning the cessation of a vow because of a notable change of matter apply here.
e) "If the other has stood by his promises." For let faith be broken with one who breaks faith; or, as Rule of Law 75 in VI° says: "In vain does anyone ask that faith be kept with himself by one to whom he refuses to keep the faith pledged by himself."
Third rule. A promissory oath generally follows the nature and conditions of the act to which it is added; therefore, if such an act tends directly to the harm of others or to the prejudice of the common good or of eternal salvation, it obtains no firmness therefrom.594 The reason is that an oath is assumed for confirming an act by adding an obligation of religion, and therefore it is something accessory to the principal act. But "it is fitting that the accessory follow the nature of the principal," as Rule of Law 42 in VI° says. From this rule it is deduced that one who swore that he would observe the decrees and statutes of some congregation, chapter, or University is not bound to observe all these otherwise than they are observed by the other good members of the same society. Hence those things which are commonly neglected can also be neglected by him; those things which of themselves bind under light sin are not to be observed otherwise because of the oath made; those things which bind from a certain fittingness alone also do not bind more from the oath.595
591 Code of Canon Law, c. 1321.
592 Ib., c. 1319, n. 1.
593 Ib., n. 2.
594 Code of Canon Law, c. 1318.
595 Cf. St. Alphonsus, Theol. mor. l. 3, n. 181. Even an oath concerning keeping a secret is understood according to the gravity of the matter, so that the violation of this secret in grave matter is a grave sin; in light matter, a light sin; in matter of no importance, no sin. Cf. Billuart, l.c.
455. 3. The cessation of the obligation of a promissory oath can be produced either by extrinsic causes or by intrinsic causes. From intrinsic causes the obligation of an oath ceases in almost the same way as a vow, namely, through a substantial change of matter (as if it has become unlawful or impossible); through the cessation of the essential end (as if someone promised alms by oath to poor Peter, who has now suddenly become rich or has died); through the failure of the condition under which the oath was made.596
The extrinsic causes which produce the cessation of an oath are:
a) the remission by the other person in whose favor the promise confirmed by oath was made, as is clear from the second rule, letter c), cited above.
b) invalidation, dispensation, commutation. Before the Code of Canon Law was published, certain controversies existed concerning this matter. But now c. 1320 simply establishes: "Those who can invalidate, dispense, or commute a vow have the same power and in the same manner concerning a promissory oath; but if the dispensation of an oath tends to the prejudice of others who refuse to remit the obligation, the Apostolic See alone can dispense the oath because of the necessity or utility of the Church." Therefore, e.g., betrothals confirmed by a promissory oath can be dispensed by the Holy See alone, unless, however, both betrothed parties consent to the dissolution of the betrothal. Apart from this oath in favor of a third person, no other seems to be reserved to the Holy See.597
c) Release,598 which differs from dispensation in this, that dispensation is customarily granted in favor of the person swearing, but release from an oath is commonly imposed because of grave reasons on the part of the one in whose favor the oath was pronounced. This release is similar to the invalidation of an oath, but since it tends to the prejudice of others, it is not exercised except by the Supreme Pontiff,599 and indeed:
a) for preventing harm to the common good. For a private good ought to yield to the common good. Therefore the Pope releases even sworn betrothals for a grave cause if, e.g., otherwise an unbelieving betrothed man would contract a merely civil marriage or live in concubinage. Certainly the betrothed woman thus abandoned can suffer great harm from such a release, but the Church cannot compel the unbelieving betrothed man to the promised nuptials, and on the other hand, for the sake of the common good, she must avoid merely civil marriages and concubinages as far as possible. b) As punishment for a crime committed. Therefore in ancient times the Supreme Pontiffs more than once released the citizens' oath of fidelity because of the crimes of an excommunicated prince. c) For repairing an injury which was inflicted upon the one swearing, if, namely, he was induced to the oath by fear or fraud.600
596 Cf. what was said above in n. 410 concerning the cessation of a vow, and Code of Canon Law, c. 1319, nn. 2 and 3.
597 Cf. St. Alphonsus, Theol. mor. l. 3, n. 259.
598 Eideslösung, délier d'un serment [release from an oath].
599 Cf. S. theol. 2, 2, q. 89, a. 9 ad 3; Code of Canon Law, c. 1320.
600 S. theol., l.c., a. 7 ad 3.