§ 2. On the Licitness of an Oath

For a licit oath three things are required: truth, justice, and judgment.

605. TRUTH in an oath is conformity of the words with the cognition and intention of the one swearing. A TWO-FOLD truth is required: one, by which a lie in asserting or promising is excluded; another, by which fiction in swearing is excluded. If the first truth is lacking, the oath is false, or perjury strictly so called; if the second is lacking, there is a fictitious oath.

606. PRINCIPLES. I. Perjury is a mortal sin from its whole genus. The reason: grave irreverence against God is committed, since he is brought forward as witness of falsity, as if either he did not know the truth, or wished or could deceive. Nor is lightness of matter given here, because it is always equally repugnant to God to testify to what is false (III, 147). - Hence this 24th proposition was condemned by Innocent XI: "To call God as witness of a light lie is not such great irreverence on account of which he would will or be able to damn a man."

607. II. A fictitious oath is a grave sin from its genus. This is established from the 25th proposition condemned by Innocent XI, which sounds thus: "With cause, it is licit to swear without the mind of swearing, whether the matter is light or grave." The reason for the condemnation is that one swearing thus mocks divine testimony and utters a lie, since he says that he invokes God as witness, and nevertheless does not invoke him. Cf. Viva, on this proposition, against Tamburini.

Hence: 1. To swear fictitiously, in confirmation of what is false, in matter whether grave or light, is a mortal sin. For thus externally it is said that God either does not know the truth, or wishes to testify to falsity; in either of which there is grave injury to God, even if someone acts fictitiously. And hence also is why he sins gravely who swears fictitiously without the mind of fulfilling a promise (Billuart, de Relig., Diss. 5, a. 6, § 2).

2. To swear fictitiously in confirmation of the truth, for example with the mind of fulfilling what is promised, is only a venial sin. "But the Doctors rightly except if the oath is made in contracts or before a judge: because then, although it is not perjury, nevertheless it is a grave deception against justice," since the other has a right that the one swearing be held by the bond of religion. The same must be said concerning him who swears without the mind of obliging himself, yet with the mind of fulfilling, that is, who conceives a mere purpose of fulfilling the matter; because this man in reality does not swear, as was said n. 603 (cf. III, 172).

Note. If there is established a just cause of the fiction, it can also happen that every sin is absent (Lehmkuhl, I, 556).

608. Questions. QUES. 1. Whether it is licit to swear with PROBABILITY of truth?

Resp. For swearing licitly, in common human commerce some moral certitude suffices, or probability, which, at least because of the absence of contrary reason, reaches a certain moral certitude; while in a judicial matter, as regards things personally known, full certitude is required, for warding off the danger of harming. Yet if someone knows a thing with probability, from the testimony of an honest man, he will be able to swear that this is held only as probable (III, 148; Lehmkuhl, I, n. 558; Genicot, I, n. 302).

QUES. 2. Whether it is licit to swear with a MENTAL RESTRICTION?

Preliminary note. Mental restriction is an act of the mind by which someone, by checking or determining the signification of words, turns his speech aside to another sense than to the natural and obvious one. One is purely mental, which can in no way be perceived by others; another is not purely mental, which can become known from the adjunct circumstances (H. Ap., V, 15).

Resp. 1. It is never licit to swear with a PURELY MENTAL restriction. Such a restriction cannot be excused from a lie; whence, if it is confirmed by oath, it is true perjury. This is established from the 26th, 27th, and 28th propositions condemned by Innocent XI.

2. It is not licit to swear with a NON-PURELY MENTAL restriction before a judge legitimately interrogating, or in onerous contracts, where reticence would be harmful to the public good or to the contracting party; and it is a mortal sin.

3. But it is licit in common speech, whenever a just cause of hiding the truth is had, namely utility or necessity of swearing thus, for preserving goods of soul or body, or of freeing oneself from importunate interrogations.

Nevertheless, on account of reverence for the oath, a graver cause is needed for sworn equivocation than for common equivocation, and the less obvious the equivocation is, the graver the cause must be. But to swear with a restriction not purely mental without just cause, more probably, is only venial: because in an oath of this sort only judgment or discretion is lacking, the defect of which is only venial (III, 151). See the other things at n. 1181. Cf. Junglas, Der rechtsgeschichtliche Hintergrund fur Liguori's Lehre vom Gerichtseid (Festschrift zum 75 Geburtst. Freih. v. Hertling, 1913). There the opinion of the Holy Doctor is vigorously defended.

Justice must be understood differently in an assertory oath and in a promissory oath. In an assertory oath justice requires that the one swearing have a right of asserting that which he says; but in a promissory oath, that the thing promised be just and honorable.

609. PRINCIPLES. I. In an assertory oath defect of justice, insofar as it is against religion, regularly is a venial sin. Thus Suarez (tr. V, l. 1, c. 2, a. 6) with the common opinion. "For this defect does not directly evacuate the end of the oath, nor make God witness of a lie; but at most it makes him witness of a depraved and unbecoming thing, which of itself is not a grave injury." If someone therefore should boast with an oath about some sin, even grave, he sins only venially by reason of the oath or religion; for the oath is pronounced for this end alone, that he may render others more certain about his sin; in which there is nothing except a certain venial lightness of mind (III, 146, 4).

It was said: regularly; for "there seems to be an exception," says the same Suarez (l. c.), "unless the oath itself is assumed as an instrument of sinning, that is, unless the malice of the depraved narration is increased through the oath: as if someone, for example, should defame his neighbor against justice by narrating a hidden truth, and, that the infamy may become more probable, should add an oath." For thus the one swearing makes God in some way a cooperator of iniquity: which is a grave sin (cf. l. El. qq. ref., n. 20; Vind. Alph., P. III, q. 9).

610. II. In a promissory oath, if the promise is about a thing gravely evil, defect of justice is a mortal sin. For it is a grave irreverence by divine authority to quasi-oblige oneself to mortal sin, so that here two malices concur: one, that the one swearing wills evil; the other, that for this he abuses the authority of God, who has hatred for every evil (III, 146). - Therefore oaths customarily furnished by those to be received into secret societies involve the greatest guilt of fault; because, at least implicitly, they oblige themselves to all crimes.

If the thing promised is venially evil, many hold that there is only light irreverence there. But "the opposite opinion pleases me more," says St. Alphonsus (ibid., 5), "because it seems not a light but a grave irreverence to invoke God as witness and surety of sin, although light"; in other words, it is grave to assume such an obligation by oath, as if wishing thus to honor God. But he sins venially who swears something against the evangelical counsels, as, for example, that he will not enter Religion, that he will not give alms. The reason is that here he rather affirms that he is so disposed.

611. From these things conclude: 1. "He sins gravely who exacts an oath from another, knowing that he is going to perjure himself. Except, unless a just cause and necessity demand it; because then the perjury follows from the malice alone of the one perjuring himself" (III, 149).

2. Rustics who do not understand the malice of perjury, and have the custom of perjuring themselves, are not immediately to be admonished concerning the gravity of the sin, lest they pass from material

sins to formal sins; but they themselves are to be strongly admonished, so that they may be called away from the bad custom (III, 150).

3. It is not licit to furnish an oath of fidelity proposed by a government hostile to the Roman Church, in words by which unlimited obedience is promised; but an oath of merely passive obedience can be tolerated, in all those things which are not opposed to divine and ecclesiastical laws, according to the form approved by the Supreme Pontiff Pius VII. Therefore if any laws of the government are opposed to the rights of God or of the Church, let a restrictive clause be added, and, that scandal may be avoided, let it be declared that the Holy See permits such an oath. Cf. S. Poenit., Dec. 10, 1860 and Dec. 14, 1866 (A. S. S., I, p. 562; II, p. 676).¹

Indeed, neither then will it be necessary to add clauses, if, whether from the character of the one swearing or from the public declaration of the prince, it is known that the oath implicitly contains the clauses. Noldin, II, 252.

Note. To this second condition of an oath can be referred the question: Whether it is licit to swear upon Protestant Bibles? It is certain that this is not licit if the government does not absolutely require such an oath. If it is imposed, a Catholic will be able, a protestation having been premised, to swear upon a heretical Bible. Let him at least premise the clause: insofar as it contains the word of God. Let confessors, as regards admonition, observe the approved rules. Those are not excusable who, a faculty having been given of asking for or bringing with themselves a Catholic version, use corrupted Bibles (Lehmkuhl, I, 552, note).

Preliminary note. Judgment demands that an oath be emitted with discretion, that is, with prudence and reverence, and not without a grave or reasonable cause (III, 144).

Therefore the one swearing must weigh: 1. whether the oath is required either by reason of his office, or for this, that faith may be given to his words; 2. whether a notable hope shines forth that he will make faith; 3. whether at its time he can furnish the thing promised by oath.

612. PRINCIPLES. I. To swear without sufficient cause of itself is a venial sin. One swearing thus, by affirming a true thing or promising that which he has the intention of fulfilling, does not seem to invoke the name of God with grave disorder.

We said of itself; because per accidens it can be mortal, if scandal or danger of perjury is present. This danger is commonly incurred by those who are accustomed to swear, without attention whether the things which they are accustomed to swear are true or false (III, 145).

613. II. For swearing licitly notable utility suffices. This is evident from the nature of an oath (cf. n. 602).

Hence, by excellent right, an oath is exacted from those who are received into some community, for example a college, that they diligently devote themselves to observing the statutes; and likewise from those who are placed over some public office or ministry, such as Bishops, canons, beneficiaries, witnesses, etc. - Wherefore, the 101st proposition of Quesnel, by which oaths customarily made in the Church are said to be contrary to the spirit of God and the doctrine of Christ, was condemned by Clement XI in the Bull Unigenitus.

Note. As Schindler rightly observes (II, p. 164), great prudence is required in officials of the State, judges, etc., when they ask that the sanctity of an oath be added to assertions. Let oath remain, for investigating truth, an extraordinary means, which they should not use too often. From atheists or perjurers who are known as such, let sworn assertion rarely be sought.