Chapter IV — What the obligation of a promissory oath is. It is compared with the obligation of a vow. What intention, or resolve, is required in a promissory oath. To swear without the intention of swearing is always a mortal sin

I. Most grave is the obligation of an oath, which, as the Angelic Doctor says, draws its origin from the divine authority itself. For the swearer interposes divine testimony in confirmation of truth, whether present, or... past, or future. Wherefore the violation of a promise confirmed by oath is perjury, which is a most grave sin.

II. In oaths made to God, a vow also commonly occurs. As often as you confirm by oath a promise made to God, both a vow and an oath are present, which are two bonds of obligation; wherefore one who violated them would commit two sins. Not always, however, in a future matter to be done for God's honor is a vow present. For if you did not wish expressly to promise, but only to propose that you would do something in God's honor, and confirmed your resolve by oath, you would be bound only by the bond of the oath. From this you commonly gather that, in promises made to God and confirmed by oath, both a vow and an oath are always found; not, however, necessarily — since, as is established from the example adduced, an oath can be found without a vow. But in all promises made to men, only an oath, without a vow, is present.

III. All affirm that the obligation of an oath is most grave. Only a few things need to be said concerning the nature of this obligation. First of all, an oath obliges after the manner of a private law, which the swearer imposes upon himself; by its own kind, it obliges under mortal sin, according to all, with St. Thomas (II-II, q. 98, art. 3). This obligation is bound by the bond of divine testimony, and pertains to the virtue of religion. Two obligations, however, must be distinguished in a promissory oath: one which arises from the promise itself, valid and accepted — and this, upon precise distinction, is an obligation of justice; the other, proper to the oath itself, pertains, as we have said, to religion. Wherefore false is the teaching of Christian Wolff, a Lutheran man, who says (On Natural Law, Vol. III, ch. 4): "An oath produces no new obligation of rendering something to him to whom one swears."

IV. It is customarily asked here whether the obligation of an oath or of a vow is greater. This little question St. Thomas himself proposes (loc. cit., art. 8), and answers that we owe God a greater obligation of a vow than of an oath — namely, that we pay him what we have promised; since the obligation of a vow arises from the fidelity which is owed to God from the reverence due him; but the obligation of an oath is born from reverence owed to God: for the bond of fidelity is greater than that of reverence. And although a vow is confirmed by an oath, it is not therefore inferred that the obligation of the oath is the greater; but only that a movable thing is more firmly confirmed by two immovable things.

V. Suárez (Bk. II, on the oath, ch. 13) distinguishes this comparison of the vow with the oath, and says that, if the comparison of the vow is made with an assertory oath, the obligation of the vow is greater than that of the oath; but if the comparison of the vow is made with a promissory oath, then the obligation of the oath is greater than that of the vow. Nor does he say that St. Thomas's teaching is contrary to this, on the grounds that the Angelic Doctor speaks only of a promissory oath, not of an assertory one. The reason Suárez alleges is valid: because the obligation of not attributing falsehood to God is greater than the obligation of rendering vows to God — since the former is negative, "Thou shalt not take the name of the Lord thy God in vain"; the latter, affirmative, "Render to the Lord thy vows."

VI. I, however, interpret St. Thomas's teaching thus. If the pure notions of each obligation which St. Thomas assigns are inspected, absolutely speaking, the obligation of a vow is greater than that of an oath, for the reason he gives — namely, that the promise of a vow regards God directly; but the promise of an oath does not regard God, since, by an oath, as such, no promise is made to God himself, nor is an obligation contracted toward him, but God is brought forward only as witness of a promise, or of an assertion concerning some future act. Wherefore, if these two respects are weighed, as St. Thomas alone considers in the cited article, the former is without doubt more valid than the latter. For the rest, if the obligation of the oath is considered in relation to the truth necessary in an oath, whether assertory or promissory, the obligation of the oath seems greater than that of the vow. This can be proved a posteriori. For one who swears falsely, so far as it depends on him, makes God the author of a lie; how enormous an injury this is to God is self-evident. For this reason, in an oath, at least an assertory one, according to all, there is no smallness of matter; but every assertory perjury is a mortal sin. I have proved the same to occur in promissory perjury. Therefore the obligation of an oath, whether assertory or promissory, with respect to the truth to be subjected to the oath, is greater than the obligation of a vow. Since it is by no means so certain that a smallness of matter cannot be found in a vow; indeed, several concede that it can be found in a vow, though not in an oath.

Nor should you say that, in practice, these two respects cannot really be distinguished — since a promissory oath tends to this: that it obliges the swearer to the execution of the promised thing, which execution is the truth of a promissory oath; nothing, nonetheless, prevents the promise of the oath, absolutely, from being considered as compared with the promise of a vow; indeed, in fact the Angelic Doctor considers these two promises in relation to God directly; and, because the promise of a vow regards God more directly, it is therefore stronger, in the notion of a promise, than the obligation of an oath. For it seems, says the Angelic Doctor, a most grave irreverence toward God to institute a subject for a promise, or to render a vow. For the rest, if the obligation of the oath is considered by respect to the truth to be subjected to the oath itself, lest it turn out false, and God be invoked as witness of a lie, then the obligation of the oath seems, as I have said, greater than that of the vow. What is conceded of an assertory oath by Suárez, Sánchez, Leander, and others — though they deny it of the promissory — seems to me the same reasoning applies to both oaths. And, to defend this opinion which I have explained, the authority of the Church impels me, which declared that a smallness of matter is not given in perjury; though several authors explain this declaration of the Church concerning an assertory oath, we, nonetheless, from the very words of St. Thomas, have demonstrated above, that a smallness of matter is in no way given, either in a promissory oath, or in a vow, although this opinion has for a long time prevailed. If, however, this interpretation of ours does not please someone, let him assert what seems to him better. We embrace it, since we judge it opportune for explaining St. Thomas's teaching, from which take care never to depart, especially in those matters which depend on right reason — for his acuteness is incomparable.

VII. Question I. What intention, or resolve, is required for a promissory oath to induce an obligation? Response: That an oath depends on the intention of the swearer, so that the intention, or will, of swearing is necessary, for an oath to give rise to an obligation, is certain among all — since human actions which admit an obligation require the consent of the will; a consent which is not given by one who positively refuses to give it. Since, then, an oath induces an obligation of speaking the truth concerning a present or past matter, or of executing a future thing (which is the truth of a promissory oath), it is therefore necessary that a full consent of the will, or intention of swearing, be present. Whether this will, or intention, must be express, or implicit, actual, or virtual, will be said below, concerning the custom of swearing. This much is certain, and commonly defended by authors: that, if someone were to swear with the express will of not swearing, it would not properly, and in rigor, be an oath — just as it is certainly maintained by all, that an oath externally pronounced, without the intention of swearing, contains the irreverence of divine testimony, and inflicts an injury on God.

VIII. For you to perceive this matter more clearly, however, you ought to distinguish the resolve of swearing, the resolve of promising, the resolve of executing the promise, and the resolve of binding oneself. All teach, as we have already seen, that one who swears without the resolve of promising, and of fulfilling, sins mortally. It is also more probable that one who swears without the resolve of binding himself sins mortally; and this seems certain to me, whatever Valentia may say to the contrary. Concerning one who swears without the intention of swearing, it must now be inquired.

IX. Question II. Is it lawful to swear without the intention of swearing? Response: Thomas Tamburini (Bk. III, ch. 3, §1, n. 1) writes this: "It is certain that it is lawful to swear without the intention of swearing, whether the matter be light or grave, without cause; or to swear in ambiguous words, is not lawful without cause, according to what we have said in ch. 2, §2." This assertion of Tamburini's was condemned by Innocent XI, in proposition 25, which is of this kind: "With a cause, it is lawful to swear without the intention of swearing, whether the matter be light or grave." Fr. Viva, in his exposition of this proposition, n. 1, contends that it is not established in what sense Tamburini taught his proposition; since, he says, the passage to which Tamburini refers the reader is desired — but the passage is found on the same page. For, as to what pertains to this, Tamburini says it is lawful to swear without the intention of swearing, or to swear in ambiguous words, with cause, according to what he said in ch. 2, §2. What, then, does he say in that place? Here are his words: "The question is, whether it is lawful for the swearer to take words in another sense than that which they present. For example, by God I..." 'I have not slept this night' — understanding, dressed. Response: it is lawful... But is it not at least venial to swear thus by equivocation? Response: If some cause underlies it... no sin at all. If there is no cause, it will be venial."* That is the passage which Fr. Viva denies is to be found; and yet this passage, in this place, has not a word about a tyrant, nor about a confessor. Let this be said in passing, not so much to prove that Tamburini is the author of the condemned proposition (for this pertains neither to me, nor to my purpose) as to warn readers to read Fr. Viva himself cautiously in his exposition of the condemned propositions. For, in order to prove that Tamburini did not teach the condemned proposition, he himself, if he does not expressly and absolutely fall into the sense of the condemned proposition, at least, as my own opinion suggests, does not depart from it at all. Here are Fr. Viva's own words: "For if he only contends that a confessor may not reveal the sacramental seal, he can, the tyrant urging it, with an oath deny that the penitent sinned, either by using equivocal words, or by speaking materially — that is, by pronouncing the words of an oath not as signifying, and therefore without the intention of swearing — he is not to be marked as the author of this exploded thesis, since it only wishes that it be lawful, from some cause, whether light or grave, to speak formally, and to swear without the intention of swearing."

As for what concerns Tamburini's own deed, it is clear what he himself thought from what we have said. As for what pertains to Fr. Viva's own teaching, it does not seem to me entirely free from the sense of the condemned proposition. For who would say that it is illicit to swear formally without the intention of swearing, but licit to swear materially without the intention of swearing, and this for a grave cause without a grave cause? For thus a broader means would be available for evading all the condemned propositions. The oath of a confessor for guarding the seal is explained by the Fathers, and the ancient theologians, in an altogether different manner. Of this more below. From Fr. Viva's teaching it is clearly inferred that it is licit to swear materially without the intention of swearing, whether the cause be light or grave. He says, indeed, that the proposition was therefore condemned, because it holds it lawful, from some cause, whether light or grave, to swear formally without the intention of swearing. This follows legitimately from Fr. Viva's teaching. I do not sense such an interpretation to be at all repugnant to the Church's teaching; for it follows only, from some cause, either grave, or most grave, that it will be lawful to swear materially without the intention of swearing. But that it will be lawful to swear formally without the intention of swearing, from whatever cause, whether light or grave, is what Fr. Domenico Viva not infrequently evades, and reduces to nothing, the condemned propositions, by his own subtleties, as no one fails to see, as I at least judge.

X. The reason for the condemned proposition, however, is evident. For one who swears without the intention of swearing — whether he swears something true, or false, whether in a grave matter, or in a light one — always commits a lie. For one who says, "I swear," and really, with internal mind, does not wish to swear, lies. But a lie is never lawful. It should be added that this lie is sacrilegious, since it abuses the usurpation of the divine name. Finally, the external invocation of the divine name in this manner produces, among men, great scandal, and inflicts most grave injury on divine truth.

XI. Question III. Does one who swears something false in grave matter without the intention of swearing sin mortally? Response: All respond affirmatively — since the external invocation of divine testimony in confirmation of falsity inflicts a most grave injury. For just as one who burned incense to an idol without the intention of burning incense would be guilty of idolatry, and one who uttered words of blasphemy without the intention of blaspheming would sin mortally with the sin of exterior blasphemy — so, by the same, or an equal, reasoning, one who, to confirm falsity, externally invokes divine testimony without the intention of invoking it, sins gravely.

XII. Question IV. Does one who swears something false in light matter without the intention of swearing sin mortally? Response: Fr. Viva (loc. cit., n. 6) seems to defend, as probable, the opinion teaching that it is not a mortal sin to swear something false in light matter without the intention of swearing; and he alleges reasons for this opinion. The chief one he adduces is drawn from a parity with a promissory oath and a vow, whose transgression in light matter is not a mortal, but a venial, sin. The same, then, he concludes, must be said of an exterior oath without the internal intention of swearing. Nor does he resolve this reason, which he explains at length; he only reports Verricelli, who teaches the opposite, and, following the custom of several colleges, leaves the reader the faculty of choosing either opinion.

That the principle on which Viva relies is false, we have already demonstrated in ch. 1, q. 3; and, this being granted as well, the conclusion which Viva draws does not follow.

XIII. For this reason I say it is certain that to swear something false without the intention of swearing, even in light matter, is a mortal sin — both because the gravity of the profanation of the divine name is not taken so much from the gravity of the matter, in whose confirmation it is invoked, as from the infinite dignity, and majesty, of divine testimony, and of uncreated truth; and because, just as in idolatry and blasphemy no smallness of matter is given, so neither is it given in an oath, whether promissory or assertory. It should be added that the question chiefly concerns an assertory oath, or an oath absolutely taken; indeed, as Suárez notes (Bk. III, ch. 17, n. 1), fiction has place only in an assertory oath — since fiction, whether of intention, or of words, is committed only while the oath is being conceived and pronounced. It is clear, however, that perjury, absolutely taken, even in light matter, is a mortal sin. And since this opinion is called into doubt by no one whom I have seen, except by Fr. Viva, I therefore abstain from a longer proof.

XIV. Question V. Does one who swears something true without the intention of swearing sin mortally? Response: Cajetan (II-II, q. 89, art. 5, dub. penult.), Covarrubias (Bk. 1, Variae, Part 5, n. 3), Armilla (s.v. Perjurium), Filguera (in his exposition of the condemned propositions) uphold the affirmative part — since it is a mockery of the divine name, and a deception contrary to the primary end of an oath. Suárez (Bk. III, ch. 17, n. 6) reckons this opinion too rigid, yet at the same time defines it as probable. Nonetheless, he defends the contrary as more probable, to which accede Cárdenas (dissert. 18, on the condemned propositions, ch. 2), Castropalao (disp. 1, punct. 8), Bonacina (disp. 4, q. 1, punct. 7), Lessius (On Justice and Law, Bk. II, ch. 42, dub. 8, n. 42), Sánchez (Bk. III, ch. 6), Viva (on the condemned propositions, n. 5), La Croix (Bk. III, part 1, dub. 14, n. 155), who all teach that to swear something true without the intention of swearing, in light matter, is only a venial sin, provided the oath is not made in judgment, in a contract, or in a similar circumstance, in which one's neighbor could suffer some detriment. The reason of these Doctors is that the lie which someone commits, when he swears something true without the intention of swearing, is injurious neither to God, nor to man: not to God, since he is invoked externally in confirmation of a truth; not to man, since it is taken as certain that neither a contract, nor anything in which a man could suffer some grave harm, is to be confirmed by this oath; and although one's neighbor may be deceived, since this oath is supposed to occur in human commerce, that deception is nonetheless not grave, since it inflicts no grave harm. These are the reasons for this opinion.

XV. It must be observed that several of the cited authors taught the recited opinion before the proposition was condemned by Innocent XI. Those, however, who wrote after the condemned proposition contend that it was therefore condemned, because it asserts that it is lawful to swear without the intention of swearing, from whatever cause, whether light or grave. For the rest, they themselves teach that it is always illicit to swear without the intention of swearing, from whatever cause; and therefore they say they keep themselves free of the sense of the condemned proposition.

XVI. The first opinion of Cajetan, Armilla, and others is true. Indeed, it is probable enough that the contrary opinion is contained in the condemned proposition. And indeed, if we once admit that it is in our own power to take away from words their formal signification, or that which words present according to everyone's understanding, and to substitute a material one — that is, one signifying nothing (just as if we should say "Butiri," says Fr. Viva) — human commerce as a whole would necessarily collapse. But of this in what follows. We now bring forward the reason why the opinion which maintains that one who swears something true without the intention of swearing sins mortally appears true to us. And first, it is not necessary that I recall to memory that an oath is, among all peoples, of such dignity and veneration, that it ought to be employed only under an urgent cause. All teach that the use of an oath, even in confirmation of a true deed, and without any deception, is a venial sin from a defect of judgment, and is called by St. Thomas an incautious oath. It is likewise certain that a swearer without the intention of swearing commits a lie — and this the patrons of the contrary opinion concede. It is beyond dispute that a swearer without the intention of swearing commits, in this genus, or line, two grave venial sins. Then it is certain that, besides these two grave venial sins, an abuse of the oath intervenes, because the lie itself is covered over with the sacred veil of the oath. For although divine testimony is not invoked in confirmation of an internal lie, but of that truth which the swearer intends to confirm, nonetheless, in the very abuse of the oath, a lie is committed, and under the oath a lie is concealed. Finally, who would dare deny that one who swears without the intention of swearing mocks divine testimony, and inflicts an injury on divine truth, while a lying mind is concealed under the patronage of that invocation? But, as I have often said, the gravity of the malice in the abuse of an oath is not taken from the gravity of the matter upon which it falls, but from the infinite dignity of the name which is brought forward as witness. But because this question is almost entirely speculative, and too remote from practice, I do not wish to discuss it at greater length. For a cause can indeed occur why someone might swear something true and at the same time not have the intention of swearing. This can certainly happen to no one, unless he is stupid.

XVII. Question VI. Does one who deliberately swears without the intention of swearing utter a true oath? Response: Authors commonly teach that a true oath is not present, from the defect of the intention necessary for an oath; and no one calls this into doubt. But, for greater clarity of what has been said, it is worth explaining the proposed question... as briefly as possible. To explain, then, in a few words, what I myself think, I say that one who seriously, and deliberately, invokes divine testimony in confirmation of truth, saying, "By God it is so," truly utters an oath, and truly swears, although he may have the resolve of not swearing. To this I am moved, because the signification of words does not depend on man's will and effect. Given, then, that a man has once seriously and deliberately wished to invoke God in confirmation of truth, he can no longer, by an internal resolve, bring it about that this invocation not be an oath. And so that you may perceive the whole matter more clearly, you must observe that in a man swearing in this manner, two mutually contrary and conflicting intentions are found. The first intention, and deliberation, is that by which the swearer really invokes God as witness, and utters an external oath. The second is that by which he does not wish to swear. These two deliberate intentions mutually collide, and one prevails over the other.

Which, then, prevails? In fact, the former, since this is efficacious, and produces its effect, namely, the external swearing. The second intention is inefficacious, and a mere velleity, not an efficacious will. From this it plainly follows that this external oath is a true oath, since it proceeds from a deliberate will.

XVIII. You will object: An oath depends on the intention of the swearer; but one who swears without the intention of swearing does not have the intention of swearing: therefore he does not really utter a true oath, but only the external sound of an oath. Response: I have proposed this objection precisely so that our own opinion might shine forth more evidently. We grant, then, the first proposition; the second we deny, or, for the sake of clarity, we distinguish: one who swears without the intention of swearing does not have an efficacious intention of swearing — this I deny; an inefficacious one — this I grant. That intention is called efficacious which really produces an effect. The first intention, by which someone seriously and deliberately invokes divine testimony in confirmation of truth, saying, "By God it is so," is efficacious: for it produces its own effect, namely, the external invocation of divine testimony. The second intention, by which the swearer resolves that he does not wish to swear, is languid, and inefficacious, overcome and subdued by the former. For, in the mutual conflict of swearing and of not swearing, the former intention conquered, by force of which the oath was pronounced, and God was called to witness; and the external oath appeared to all, and the hearers took it as an oath, and finally the swearer himself wished to seem to the men he was addressing to have uttered a true oath. The second, internal intention has no power to impede the signification which those words, "By God it is so," present — in the same manner in which the second intention, by which a merchant might not wish to throw his goods into the sea, does not impede the first intention, by which he really does throw them, because the effect is really produced. There are, then, two intentions, both internal. But the first can be called external, because it externally produces its own effect, namely, the invocation of divine testimony; the second is merely internal, because it produces nothing externally. He would indeed wish to impede that external invocation from being a true oath; but he cannot accomplish this, because, by this very fact that the first intention prevails, of pronouncing seriously and deliberately those words which contain a true oath, the will can no longer take away from those words their own proper signification.

XIX. Question VII. Does one who, from a slip of the tongue, swears something false, sin mortally? Response: I have often laid the foundation for interpreting this, in the following little question: namely, that the invocation of God as witness is grounded in the intention. If, then, it happens, unforeseen, that men swear something, without adverting whether it is true or false, guilty of perjury, from a slip of the tongue, that is, without deliberation, this man is interpreted not to have had this intention of invoking God as witness. If, however, someone advertently swears, he sins mortally. Thus St. Thomas answers (II-II, q. 98, art. 3, ad 2): "He who swears falsely from a slip of the tongue, if indeed he adverts that he is swearing, and that what he swears is false, is not excused from mortal sin, any more than from contempt of God. If, however, he does not advert to this, he does not seem to have the intention of swearing, and therefore is excused from the crime of perjury."

The Angelic Doctor's words are to be considered with the utmost care. For which reason the Angelic Doctor interprets those who utter words from a slip of the tongue, that is, beyond their intention, as not having the intention of swearing, and therefore these are said to contain a lack of the crime of perjury.

An oath, then, depends on intention, insofar as a man ought to know, and advert, that he is uttering words which constitute an oath; and, while he adverts that he really invokes God as witness by such words, and nonetheless deliberately pronounces those words, then he swears, even if he does not have the intention, or even if he had the contrary intention of not swearing. Indeed, if he adverts, while he adverts, that the words he pronounces have the force of invoking divine testimony — indeed, he knows the words he pronounces to have the force of invoking divine testimony.

It must, moreover, be distinguished, this phrase of the Angelic Doctor's, "from a slip of the tongue," from a wicked habit, of which more below. For one who is accustomed to swear, and has contracted the habit of swearing, although he may not advert that he is swearing, while he pronounces the oath, is not said to swear from a slip of the tongue, but from a most wicked habit. These are the words that can only be said to swear from a slip of the tongue, who in no way are accustomed to swear, but who sometimes, from a slip of the tongue, can pronounce words which contain an oath, without having the intention of swearing — that is, without having the intention of pronouncing that invocation of divine testimony — unless necessity compels it.

XX. Question VIII. Is one who swears without the intention of binding himself really obliged? Response: Sylvester (s.v. Iuramentum, 4, q. 7), Azor (Part I, Bk. XI, ch. 10), Sánchez (Bk. III, ch. 6, n. 2), Bonacina (Vol. II, disp. 4, q. 1, punct. 6, n. 3), Castropalao (tract. 14, disp. 11, punct. 2, n. 6) defend the negative opinion, on the grounds that one who swears without the intention of binding himself does not really swear; since the obligation does not pertain to the essence of the oath, or is nothing consequent upon the essence of the oath. It follows, then, that one who does not wish this obligation does not wish the oath itself. Now, if it is not a true oath, there will be no obligation of executing what has been promised under oath.

XXI. The contrary opinion is defended by Cajetan (II-II, q. 89, art. 7), Sotus (Bk. VIII, q. 1, art. 1), Becanus (q. 4), Aragón (II-II, q. 89, art. 7, dub. 4), Sayr (in Clavis Regia, Bk. III, ch. 6, n. 8), Valentia (II-II, disp. 2, punct. 4), Lessius (On Justice and Law, Bk. II, ch. 42, dub. 8, n. 38), Suárez (Bk. II, ch. 7), and several others. This opinion is more probable, and seems true to me. The reason is easy. For an oath, as the adversaries themselves confess, includes an obligation, whether as something pertaining to the essence of the oath, or as something consequent upon that same essence. Therefore one who deliberately wills the oath ought, by that same will, also to will that which necessarily follows the oath itself. The preposterous argumentation which the adversaries use is null. Since the prior intention really has its effect — namely, the oath pronounced — the later intention, which is inefficacious, cannot destroy the former. From these two intentions, then, the first prevails, and the second succumbs. The matter is self-evident. Consult what has been said in q. 6.