Article I. On the Conditions of an Oath

307. Two things are required for an oath, namely: 1. The intention of swearing, at least virtual; because without such intention a formal oath cannot exist ¹. 2. An oath-formula, either explicitly by God, or implicitly by creatures; because, since God is invoked as witness, it is necessary that this be expressed in the oath. - St. Alphonsus, n. 134.

¹ Intention of swearing contributes so much to the validity of an oath that, if this mind is present, a person truly swears (for the internal forum), although the words may be less suited to express the invocation of God, and therefore among others (as also in an oath by a merely internal act) he does not in reality swear; and contrariwise, when that intention is lacking, there is no oath, even if the words are juratory, whether that intention is lacking because of the deceit of one fictitiously swearing, or because of the ignorance of one not knowing what the act of swearing means. Laymann (lib. 4, tr. 3, c. 1, n. 3); Suarez (De Religione, tr. 5, lib. 1, c. 11, n. 2); Croix (lib. 3, p. 1, n. 258).

308. Resolves. 1. A fictitious promissory oath, or a merely external one, is not valid, because of a defect of will or intention. But one swearing thus sins; yet more probably, speaking per se, only venially, because it is nothing but a lie with a vain usurpation of the Name of God ². - St. Alphonsus, Homo apostolicus, n. 17. Often, however, this is mortal by reason of common or particular harm.

² You have on this matter proposition 25, proscribed by Innocent XI: "With cause it is lawful to swear without the mind of swearing, whether the matter is light or grave." Besides, St. Alphonsus, both in the cited place and lib. 3, n. 172, certainly teaches with the common opinion that one sins venially; but he limits this, if one swearing fictitiously thus otherwise has the mind of fulfilling the things promised; for otherwise, he says that one sins mortally. See the reasons in Sanchez (Decal., lib. 3, c. 6, n. 8-10).

2. More probably, an oath made with the mind indeed of swearing, but not of obliging oneself from religion, is not valid, because this is nugatory. But an oath made with the mind of swearing indeed, but not of obliging oneself from justice or from fidelity, is valid.

3. It is an oath to say: "I swear by God, by the Saints, the temple, the cross, the altar, the Gospel, the Catholic Faith, the Church, heaven, earth." Likewise to say: "I call God to witness... May God be witness to me... I invoke God as witness." It is otherwise if someone swears by creatures in which the divine goodness or power does not shine forth in a special way, for example by the beard, etc. - St. Alphonsus, n. 134, 138.

4. It is not an oath to say: "God knows... I speak before God," etc., if these are uttered narratively; but otherwise if invocatively, which is discerned from the circumstances or the intention of the speaker. Nor is it an oath to say: "This is as true as God exists... as I exist... as I am in this place... on the faith of a good man ³... by my faith... by my conscience... may I die... or may the devil destroy me," unless it is so intended ⁴. Indeed, according to St. Alphonsus, it is not even an oath to say: "I swear," or "I swear that it is so," unless a question about furnishing an oath has preceded. - St. Alphonsus, ibid., and many others.

³ The same is to be said of a priest interposing his priestly faith or holy consecration (c. Si quis presbyter, 4, caus. 2, quaest. 5), or of kings or princes, etc., who in place of an oath pledge on the faith, or by the faith, of a king, prince, soldier, etc.

⁴ On these things St. Alphonsus says (lib. 3, n. 143): "The words, 'May I be killed if this is not so,' and similar words, although they are true oaths if they are said by way of execration... besides, commonly they contain nothing except a certain pledge or obligation to punishment." Therefore the rule which the author sets forth first must be applied, namely that the words, and also usage, circumstances, and the intention of the speaker be inspected. But the invocation of God, and thus execration, is more easily understood where the matter concerns events which, according to the common sense of men, are judged to be disposed and directed by the special providence of God.

** To the other formulas St. Alphonsus (l.c.) also adds this one: "So may God favor me"; and he alleges the Salamancans, tr. 17, c. 2, n. 27. But the Salamancans do not have it thus, but thus: "May God favor me better"; which is very different.

309. A threefold condition is required for the lawfulness of an oath, according to that saying of Jeremiah 4. 2: "You shall swear: The Lord lives, in truth, and in judgment, and in justice."

I. Therefore truth is required, that is, conformity of the assertion with the intention and cognition of the one swearing. Therefore it excludes every lie, but not every error. In an assertory oath, truth regards the existence of the fact; in a promissory oath, the existence of the intention ⁵.

⁵ In a promissory oath an assertory oath is also included; for a person both calls God as witness that he now has the intention or will of doing what he promises, and, by employing the same God somehow as surety of the promise, assumes from the virtue of religion the obligation of fulfilling the promise. Nevertheless someone could swear only concerning his present purpose or intention, for example: "I swear that I now have the will of going to Rome next month"; and certainly someone could afterward break such a purpose without perjury. Laymann (lib. 4, tr. 3, c. 4, n. 4).

II. Judgment, that is, that it be done with discretion, prudence, consideration, and reverence, and not without necessity or grave cause.

III. Justice, that is, that the oath be concerning a just, lawful, and honorable matter: thus he would swear against justice who by oath obligated himself to inflict damage unjustly upon his neighbor, or to do anything else prohibited. - St. Alphonsus, n. 144 ⁶.

⁶ Many doctors require justice not only in a promissory oath, but also in an assertory oath, yet with this distinction: that in a promissory oath they seem to consider the defect of justice with regard to the thing sworn, but in an assertory oath with regard to the act itself of swearing.

And here the Salamancans (tr. 17, c. 2, n. 45-47), whom St. Alphonsus follows (lib. 3, n. 146), having posed the question whether a defect of justice is a grave sin even in an assertory oath, introduce Soto with Toledo, Ledesma, and Aragon as affirming, and oppose to them Suarez with Sanchez, Tamburini, and others; and they confess that they follow these, except in the case of grave detraction confirmed by oath. But this disagreement among the doctors is plainly imaginary. For Soto (De Iust. et Iur., lib. 8, q. 1, art. 3), Aragon (In 2.2, q. 89, art. 3), and de Ledesma (Sum. hisp., tom. 2, tr. 11, c. 2, dub. 4) say that he sins who, revealing hidden crimes, confirms them by oath; but they do not say whether he sins gravely or lightly. Toledo (lib. 4, c. 21, n. 8) holds that the sin is grave or light according to the nature of the matter; and indeed these authors observe that every sin can be absent, if a just cause is present, for example of revealing a hidden crime to a judge with an oath. But Suarez (De Religione, tr. 5, lib. 3, c. 12, n. 7-8), with Sanchez and others, whose opinion St. Alphonsus calls more probable, judges that the fault is generally light, because the thing sworn is supposed true, and only judgment is lacking in the swearing. Nevertheless he excepts an oath added to the narration of a true crime for the purpose of procuring greater credibility for it, because in that way the oath is assumed as a means to iniquity.

** Here the VV. deny that the disagreement of the doctors, of which the Salamancans speak, and after them St. Alphonsus, is imaginary; and therefore through eighteen columns (pp. 260-269) they wish to prove that disagreement actually existed among the doctors. But perhaps the VV. themselves do not sufficiently beware of the rock upon which the Salamancans rather often strike, because they consider too little whether the authors whom they present as dissenting dispute about the same matter and under the same respect, or rather about a diverse matter or under a diverse respect; whence it happens (as was noted at this place in another edition) that they wrongly feign battles of the doctors, and then enter into battle now against these, now against those. Whether this has happened in the present case must now be seen briefly.

According to the Salamancans, the disagreement of the doctors resides in this: that some condemn the defect of justice in an assertory oath as a grave fault, others as a light fault. Now let this be set aside for the moment: that even those authors whom the VV. allege (p. 267), namely Navarrus, Bonacina, Concina, Collet, Potestas, and Voit, would prove this disagreement to be imaginary, since they generally hold that the sin is grave or light (as Bonacina says) according to the gravity or lightness of the matter. But let these be omitted, since, as the VV. also observe (ibid.), they do not sufficiently determine the state of the question.

Marcus Struggl has the question better determined (tr. 5, q. 3, art. 1, n. 9), where he asks what sort of sin an oath from defect of justice is. And he responds: "An assertory oath concerning an unjust thing, if the assertion is just, is not a sin; because the unjust thing is only the material and extrinsic object of the oath... Thus, therefore, a witness can swear in court that Peter committed homicide... But if the assertion itself is gravely unjust, then the oath also, as its confirmation, is gravely unjust; but if it is lightly unjust, then the oath also is a lightly unjust confirmation. Hence he who discloses another's hidden crime, and gravely defames him, and confirms by oath the crime committed, sins mortally by swearing; but he who discloses another's light crime, and confirms the committed crime by oath, sins venially by swearing."

No less clearly Peter Catalani says (Th. Mor., part 2, q. 9, c. 4, n. 6): "It must be said secondly that the defect of justice in an assertory oath is grave or light, not from the grave or light thing asserted, but from the grave or light mode of asserting, namely from the evil mind, greater or lesser, by which God is brought in as witness of the thing asserted... so that, because of your evil end, it may be rendered safer and firmer. Therefore if the end for which you use an assertory oath as a means is mortal, the oath will be mortal; but if it is venial, the oath will be venial. Thus Sanchez, Suarez, Castropalaus. Hence if you gravely detract from your neighbor, and confirm the detraction by oath for the end of gravely harming him, you would commit a grave sin beyond the detraction from defect of justice in the oath; for you would assume the oath as a means to confirming grave iniquity. But if you detract lightly from your neighbor, etc."

Here indeed one begins to ask: What is the reason that Suarez and Sanchez are here alleged for this doctrine, when the Salamancans say that these stand for light fault against Soto, Ledesma, and Toledo, as though these stand for grave fault? But further, what, I ask, does Toledo say on this matter? Behold (Sum., lib. 4, c. 21, n. 8): "Concerning justice, observe that it is not enough to swear what is true, for the oath to be lawful, but one must swear with justice; that is, a man ought not to swear that truth which it is a sin to reveal. For if someone were to reveal another's hidden crime, defaming him, he would sin, although he spoke the truth, because he acts against justice; and if he swore this truth, he would sin again. But this oath is mortal when the injustice upon which one swears is mortal; it is venial when the injustice is venial." Thus far Toledo. Do these things differ even in the least from what, according to Catalani as witness, Sanchez and Suarez teach?

And what does Soto say? You may see it with your own eyes. After he has related (De Iust. et Iur., lib. 8, q. 1, art. 3) the opinion of Cajetan, as though justice were not the companion of an assertory oath, he adds: "But perhaps more rightly it is judged that justice also properly belongs to an assertory oath. For justice properly regards not only the thing sworn, but also the cause of swearing, as St. Thomas says in the solution to the second... Hence if I, asserting under oath crimes of a citizen wholly hidden, denounce them, certainly the oath is unjust... But if, required by law and custom, I reveal those things, my oath becomes just." Here the VV. subsume (p. 262) that Soto must surely be understood of mortal sin. - Resp. This will be admitted when they have shown that whatever is unjust, according to the mind of Soto, is a mortal sin of its whole genus.

From Ledesma the VV. (p. 263) report these words: "But if justice is taken in the other sense, it always accompanies a lawful assertory oath; since if the cause which moves one to swear is not just, the assertory oath will be iniquitous." Do the VV. wish even Ledesma to hold as grave sin whatever is not just? Therefore let them not conclude that the Salamancans rightly attributed that doctrine to Ledesma. For it was vigilantly said in the Note above that Soto, Ledesma, and Aragon said that one sins in the case; but whether gravely or lightly, that they do not say; nor did the aim either of Soto or of Ledesma require this further.

But that Catalani rightly attributes this common doctrine to Sanchez is clear from these words (Decal., lib. 3, c. 4, n. 33): "More clearly Soto, Aragon, Peter de Ledesma, and Toledo say that for the honorableness of an assertory oath justice as companion is required, and that this is attended not only on the part of the thing sworn, but also on the part of the cause of swearing, and therefore an oath is unjust whenever by it a neighbor's crime is unjustly uncovered. And Soto and Ledesma add that this oath is no less unjust than when an unjust thing to be done is promised by oath. And Toledo says that this sin is mortal when the sworn assertion is mortal, and venial when it is venial." Sanchez adds that he admits these things, and that they are also held by Sayrus and Suarez.

The things said up to this point can and indeed ought to seem sufficiently clear, and at the same time sufficient to persuade that the disagreement of authors in this question is imaginary. Nevertheless it is worthwhile also to hint whence the occasion arose for the confusion which this question presents among the Salamancans.

Namely, there were those who extended more broadly the justice which is the companion of an oath. Hence that saying of Tamburini (Decal., lib. 3, c. 1, §4, n. 5): "Justice consists in this: that what is sworn is sworn honorably and without sin... for here justice is not taken strictly for the virtue of rendering to each his own, but broadly according to that saying: 'It is fitting for me to fulfill all justice.'"

But Sanchez explains this thus (l.c.): "According to the opinion of some, whenever someone by an assertory oath affirms a matter in the assertion of which mortal fault is committed, then by asserting it there is, besides that mortal fault of the assertion, another mortal fault of the oath from defect of justice. And if a venial fault is committed in the assertion, there is another venial fault by reason of the oath, as we have said happens in a promissory oath." He then gives examples in this way (ibid.): "For example, if someone without just cause discloses the hidden grave infamy of a neighbor, or says a mortal contumely to him, asserting this by oath; or by oath relates his own mortal crime with boastfulness or delight over it; beyond the mortal sin of detraction, contumely, boastfulness, or delight, that oath is mortal from defect of justice." He alleges St. Thomas (2. 2, q. 89, a. 3 ad 2), Cajetan (ibid.), and Valentia (2. 2, disp. 6, q. 7, punct. 3), who nevertheless merely say that the justice of an oath regards the cause of swearing, and the example touched on by Valentia is referred to justice strictly so called.

But whatever may be the case about this, it is certain that Suarez also considered the justice which is companion of an oath in that broad sense of which we have spoken. For diverse circumstances or hypotheses he thus gives diverse judgment concerning the guilt of the assertion. "Although," he says (De Iuram., lib. 3, c. 12, n. 7), "the narration is about a mortal sin, often it is not itself a sin, at least not mortal, because it is not done with complacency in it, nor with injury to a third party, nor with scandal; indeed if that narration has an honorable cause or necessity, there can be no sin; but if it is done lightly, of itself it will only be a venial sin. Therefore to confirm it by oath will either be no sin, if it is done for a good end with usefulness or necessity, or it will only be a venial fault." But as regards injury to a third party, which he supposed to be absent in this text, he does not hesitate at all to affirm that grave fault is added through an added oath. "An exception must be made," he says (ibid., n. 8), "... unless the malice itself of the wicked narration is increased by oath, as, for example, if someone defames his neighbor against justice by narrating hidden truth, and adds an oath so that the infamy may become more probable. For then the malice against religion and the irreverence toward God seem to be gravely increased, so that under this title it is necessary to explain that circumstance in confession; because the Name of God is assumed as an instrument for doing grave injury to a neighbor, which contains grave injury to God."

But in giving diverse judgment according to the diversity of hypothesis, Sanchez and Tamburini certainly followed Suarez, and therefore, in the narration of some grave sin confirmed by oath, they teach with Suarez that a light fault can intervene. Yet that does not prevent each from agreeing altogether with the same authors with regard to the question commonly proposed by authors, of which we spoke above. And indeed, concerning Sanchez we saw this above. But as regards Tamburini, it is clear from these words of his (l.c.): "Therefore he who, for example, defamed someone with an oath... would commit an oath lacking justice, to be opened specially to the confessor besides the infamy... because to take the testimony of God as a means for acting wickedly is... irreverence against God... What if the wicked action of detraction is only venial? I respond that the oath will be venially rash."

Therefore let us conclude what is manifestly clear from these premises: When the subject of the question is the same, as we have seen regarding justice of an oath taken strictly, Suarez and Sanchez and Tamburini, etc., agree exactly with Soto and Ledesma and Toledo, etc. Therefore the disagreement and battle which the Salamancans fashioned among them is imaginary. But when Suarez and Sanchez and Tamburini, etc., take the justice which is companion of an oath in a broad sense, while Soto and Ledesma and Toledo, etc., take the justice which is companion of an oath only in a strict sense, there can be no battle among them, because the subject of the question is diverse. Again, therefore, it is clear that the disagreement vaunted among them by the Salamancans is plainly imaginary.

310. Questions. Q. 1. What is a sufficient cause for swearing?

Resp. Any honorable cause of some weight, for example peace to be confirmed in families, greater security in contracts, etc. - St. Alphonsus, Homo apostolicus, n. 14.

Q. 2. Whether it is lawful to swear with probability of truth?

Resp. It is denied, because God cannot be invoked except as testimony of a certain thing; nevertheless a certain moral certitude suffices. - St. Alphonsus, Homo apostolicus, ibid. ⁷.

⁷ St. Alphonsus (lib. 3, n. 148): "Some moral certitude suffices, or a certain probability which reaches to a certain moral certitude..." Indeed Sanchez with Valentia, Suarez, and the Salamancans, with the common opinion, say more expressly that in an oath, whether assertory or promissory, probability of the asserted truth or of the fulfillment of the promised thing to be carried out suffices; provided, it is to be understood, that there is not a probable reason to the contrary.

Q. 3. Whether it is lawful to swear with a mental restriction?

Resp. It is denied, if it is purely mental ⁸; but otherwise, if it is broadly mental, from a just cause ⁹. See what is to be said on the eighth precept, n. 442 and following.

⁸ To this, according to the common opinion, pertain propositions 26 and 27 from those condemned by Innocent XI. Indeed St. Alphonsus recalls also proposition 28 to mental restriction strictly and purely taken, which reads thus: "He who by means of recommendation or gift has been promoted to a magistracy or public office can, with mental restriction, furnish the oath which is customarily required by command of the king, without regard to the intention of the one exacting it, because he is not bound to confess a hidden crime."

But others judge (see Viva on proposition 28 of Innocent XI, n. 1 and III) that here the case of restriction even not purely mental is included. For the doctors commonly agree that cases of this sort occur, in which one must abstain even from a restriction that is not purely mental; which Cardinal Lugo also indicates thus (De Fid., disp. 4, n. 67): "In certain cases there is without doubt an obligation of abstaining from equivocations, and of using words in that sense in which they are received by the hearers. 1. When from that error the hearers would fall into some grave inconvenience; and then the obligation will be from the virtue of faith or religion, when the error which they would conceive would be against faith; just as when it would be against justice or chastity or other virtues, the use of amphibology would indirectly be against these virtues. 2. When by reason of office we are bound to instruct someone and to teach truths, lest he err; and all the more, if we are bound to this after accepting payment or stipend. 3. When we celebrate onerous and mutual contracts; for we ought from justice to utter words according to the mind of the contracting party, lest we deceive him. 4. When we are commanded to respond to a judge or prelate legitimately interrogating; for we ought to respond in the sense of the one interrogating, or certainly in the sense in which he ought to interrogate."

And to this last case pertains both the example proposed in the cited proposition 28 and many others, for example if someone to be promoted to sacred orders is interrogated concerning birth, irregularities, censures, or if someone wishing to contract marriage is interrogated about impediments. For it is not lawful for these to use equivocation; but they must sincerely confess the things about which they are interrogated. Nor does it stand in the way that it seems harsh (as is objected in the cited proposition 28) to compel someone to the confession of his own crime. For, as Viva (cited place) observes, here confession of the crime is not required for vengeance, to which confession the accused is not bound unless he has been convicted by proofs; indeed, neither is it required absolutely that someone manifest his crime or defect, but only that he withdraw from his request; namely, that offices or sacred order or marriage may not be conferred upon the unworthy to the detriment of the commonwealth.

⁹ On this matter St. Alphonsus says (lib. 3, n. 151): "It is certain and common among all, that from a just cause it is lawful to use equivocation... and to confirm it by oath."

But what the just cause may be, he soon explains thus (ibid.): "A just cause can be any honorable end for preserving goods useful to spirit or body." And again (ibid.): "An absolutely grave cause is not required, but any reasonable cause suffices, for example to free oneself from the importunate and unjust interrogation of another." Indeed, as he adds with the common opinion of the doctors, n. 170, when there is a just cause of necessity or utility, one can use amphibologies in an oath, even if he spontaneously offers himself to swear.

Finally he adds (ibid.) that, according to the more probable opinion, it is venial if someone does this without cause. "The reason," he says, "is that in an oath of this sort truth and justice are already present, and only judgment or discretion is lacking, the deficiency of which is only venial." But for more examples of equivocations, which at times are useful for practice, see the same St. Alphonsus, n. 155 to 167.

Q. 4. Whether it is lawful to furnish an oath in disturbances of the commonwealth?

Resp. This depends very often on circumstances. Weigh what justice or the common good demands, and what the obligations of the required oath are, whether positive or negative ¹⁰. - But especially it is expedient to consult ecclesiastical superiors, to whom it belongs to define what is to be done according to various circumstances.

¹⁰ You would call negative, for example, the obligation which in certain modern codes of law, atheistic by their own character, is imposed, that subjects not impede certain crimes against God and good morals, whose free faculty for each person the atheistic law commands to be preserved.

311. Q. 5. What sort of sin is it to swear without truth, judgment, and justice?

Resp. To the first. It is mortal; because to bring God as testimony of falsehood is to will to destroy His truthfulness. It is also clear from proposition 24 condemned by Innocent XI.

Resp. To the second. It is venial per se, that is, with the danger of perjury set aside; because it is only a vain usurpation of the Name of God. - Thus nearly all, even the stricter authors.

Resp. To the third. Certainly it is mortal, if the matter is grave, as is clear. But more probably otherwise, if the matter is light; because from this grave injury does not seem to redound to God, since He is invoked not as surety of sin, but as witness of the purpose. - Suarez, Collet, Antoine (with whom St. Alphonsus also agrees) ¹¹, against others.

¹¹ It is said less exactly that St. Alphonsus agrees with this opinion, since he has these words (lib. 3, n. 146): "But the opposite opinion pleases me more, which Elbel holds... with March., Turr., etc.; because it seems not light but grave irreverence to invoke God as witness and surety of sin, even if light." Suarez (De Religione, tr. 5, lib. 3, c. 19, n. 3) follows the other opinion as common, giving the reason that God is merely invoked as witness of the truth, namely of the present purpose, no differently than in an assertory oath God is brought as witness concerning a past thing that is most wicked. But this reason will perhaps seem less to cohere with the notion of a promissory oath, which is commonly handed down, and also admitted by Suarez (ibid., lib. 1, c. 8, n. 2, 3), namely that besides confirmation of present truth it includes an obligation from the virtue of religion that a man make true that which he swore, according to his possibility (which are the words of St. Thomas, 2. 2, q. 89, art. 7 ad 1), by which indeed God is brought in as surety of the promise to be fulfilled, as we said above (note to n. 309) with Laymann.

Among prohibited oaths are numbered those which are customarily emitted in secret societies, whether of the Carbonari or of the Freemasons (Francs-Maçons). For an oath cannot in any way be held lawful which its authors do not wish to be manifested even to the Church.