Chapter I — On the truth and judgment necessary in a promissory oath. Little questions of no small moment are examined

I. Hugo Grotius (Bk. II, On the Law of War and Peace, ch. 13, §21) denies that a promissory oath is lawful, on the grounds that the outcome of the promised matter is uncertain. And against these oaths he adduces the text of the Gospel: "Swear not at all." But Grotius, an author otherwise weighty among the heterodox, errs, and his own error even the heretics themselves have refuted, in their notes. Wherefore, this error set aside, the opinion of the Catholics is to be explained. The concordant opinion of the Doctors, then, is that all three conditions — namely, truth, judgment, and justice — are necessary in a promissory oath, no less than in an assertory one. For the aforesaid conditions ought to accompany the oath, taken absolutely, and consequently any particular oath whatsoever. Concerning the judgment which it is necessary to examine for the necessity of swearing, nothing occurs to be said beyond what has been said in the preceding dissertation. For no oath can lawfully be made without a reasonable necessity. This necessity is now greater, now lesser, according to the diversity of the matter which is sworn. Having, then, made a general examination of this condition, which brings no new difficulty, we undertake to elucidate the truth which is necessary in a promissory oath, and which is subject to its own peculiar difficulties.

II. Question I. Is the defect of truth concerning the present, in a promissory oath, always a mortal sin? Response: It has already been said that a promissory oath includes a twofold truth: one, concerning the present... , which consists in this: that the swearer have a sincere mind of fulfilling what he promises; the other, of the future, which consists in the future execution of the promised thing. It is answered, then, to the question, that all defects of present truth in a promissory oath are always a mortal sin. The reason is evident: since a promissory oath, by reason of present truth, agrees with the assertory, as has been indicated above. Now the attestation of falsity concerning the present is always a mortal sin, even in the lightest matter; therefore also in a promissory oath, no less than in an assertory one. For in both, God is invoked as witness of a falsity, which betrays a most grave injury to him. Whether, then, a small matter, or a great one, whether honorable or unlawful, is promised, without truth concerning the present — that is, without the intention of fulfilling such a promise confirmed by oath — it will always be a mortal sin.

III. Question II. Is a defect of the second truth to be judged grave, or is one who does not fulfill a promised matter confirmed by oath, in grave matter, guilty of mortal sin? Response: All respond affirmatively — since the violation of an oath in a grave matter gravely holds God in contempt, and consequently is a mortal sin — just as it must, by a stronger right, be said of the violation of a vow in a grave matter. Nor is there any difficulty among theologians about this.

IV. Question III. Does one who does not fulfill a promised matter confirmed by oath in light matter sin mortally? Response: Theologians dispute on both sides. I will first premise what is certain among all; then I will set forth what seems to me more probable. First of all, then, all confess that one who confirms a verbal promise by oath, without the intention of promising, sins mortally — since he is thus already a perjurer, as has been said. All equally affirm that one who has the intention of promising, but does not have the intention of fulfilling, sins mortally, for the same reason: because in both cases he lies, and perjures himself. For, when someone swears that he will assume the burden of another's obligation, and in fact, from a defect of intention, does not assume it, he lies — just as one who swears that he will do something swears that he has the resolve of doing it. If, then, he does not have this resolve, he lies, and is a perjurer. All equally agree that a twofold truth is given in a promissory oath — one, concerning the present, which, as we have said, consists in the intention of promising and of fulfilling; the other, concerning the future, which consists in the execution of the promised thing. Finally, all concede that the defect of either truth in the oath is, by its own kind, and absolutely, a mortal sin.

In this, however, turns the whole controversy: namely, whether there is a smallness of matter in this second truth of the promissory oath. And a threefold opinion is repeated on this matter. The first, extreme opinion, which affirms it; another, which denies it; a third, middle opinion, which uses a distinction. If the promised matter is the whole and entire matter of the oath, though it be light — for example, if you swore, or vowed, that you would give a poor person one small coin — then the omission of its execution is a mortal sin. If, however, the matter omitted is partial — for example, if you swore that you would give ten pieces of silver, and you give only eight — then the omission is only a venial sin. But authors of both extreme opinions commonly reject this third, middle opinion, as useless. For, granting that the defect of truth in the whole matter is a lie, the same occurs in the defect of a part of the matter. For to bring God forward as a witness of a lie, in whatever way this occurs, is always a mortal sin. Setting aside, then, this middle opinion, it is brought under examination which of the two extreme opinions is more probable.

V. I say: one who does not fulfill a promised matter confirmed by oath, even though the matter be light, nonetheless commits perjury, and sins mortally. So that you may perceive the sense of this opinion of ours more clearly, I would have you note that we do not now speak of those oaths by which mothers swear to their children an apple which they do not afterward give; nor of those by which men swear that they will not go forward, or deny that they will do something, out of modesty, to honor their companions, though they nonetheless go forward. Of these, or similar oaths, I say, we are by no means speaking. Indeed, with Comitoli (Bk. II, q. 4), we confess that it would be too harsh to condemn such mothers, or well-born men, of mortal guilt — since such expressions, or oaths, are not true oaths, from a defect of sufficient deliberation; or they receive a true interpretation, which we have given elsewhere. One ought, nonetheless, to abstain from oaths of this kind. We speak, then, of a serious and deliberate oath, by which men pledge something under oath.

We choose this opinion as more probable, since, in express words, St. Augustine, St. Thomas, St. Raymond, and the weightiest theologians to be cited below teach it, as I judge. St. Augustine (Epistle 22, or 224 in some editions) has this: "Whoever deceives the expectation of those to whom he swears, cannot fail to be a perjurer." St. Thomas more clearly (II-II, q. 89, art. 7, in the body): "Just as an assertory oath, which is about the past or the present, ought to have truth, so too an oath about things to be done by us in the future ought to have truth. And therefore each oath has a certain obligation, though in different ways: for in an oath which is about the past or the present, the obligation is not with respect to the thing which already was, or is, but with respect to the very act of swearing — namely, that one swear that which is now, or was, already true. But in an oath which is rendered concerning things to be done by us, the obligation, on the contrary, falls upon the thing which someone has confirmed by oath. For one is bound to make true that which he has sworn; otherwise the truth of the oath is lacking. This is so well established, so evident, is St. Thomas's mind, that it can be evaded by no circumlocution." — as will already appear more clearly. St. Raymond (Bk. I, Summa, tit. on the oath, on perjury, p. 51, col. 1) has this: "If, when he swore, he either believed that he could, but foolishly, or he believed that he could not solve it, and had probable cause for believing, then in both cases he perjured himself, as regards his ability, in either case; not, however, as regards his will, since he had the will in both cases: because in the first case he lacked truth in conscience, and in the second, judgment. If, however, he could not pay at the term, he does not perjure himself for this cause. Much more is he excused, if he sent it at the due time, but the money was lost by chance in transit, as is gathered from the chapter "Querela," Extra, on the oath, from the canon "Si nulla," cause 23, q. 8, and canon "Sicut," dist. 1, on consecration. If, however, once the term has elapsed, he could pay, and does not pay, he would be a PERJURER. For the lapse of the term does not dissolve the obligation of the oath, as is gathered from the chapter "Cum dilecti," Extra, on deceit and contumacy."

The Catechism of Trent teaches this same opinion (Part III, on the 2nd precept, n. 13), where it proposes this question: "How does one sin who does not keep what he has sworn, or vowed, that he would do?" It responds: "Of the same sin (namely, of perjury, of which discourse was had in the preceding number) is he to be judged guilty, who promises by oath that he will do something, when either he had no intention of fulfilling the promise, or, if he had, he does not in fact perform what he promises." Gerson, in his exposition of the precepts of the Decalogue, on the oath and perjury, says: "As to an oath concerning future things, a person immediately perjures himself when he has the firm will of not fulfilling it, or when he does not fulfill it in fact." St. Antoninus (Part II, tit. 10, ch. 7, on perjury, §1): "In a promissory oath, if one omits to fulfill what he promises, on account of a legitimate impediment, he is excused from mortal sin, according to Peter of Tarantasia. The same is taught by Bonaventure, on Bk. IV, dist. 39, first chapter, where he fully proves that every perjury is a mortal sin." Therefore, on the contrary, he is not excused, when a legitimate impediment is lacking. Read the whole chapter, where he fully proves that every perjury is a mortal sin. Wherefore that passage cannot be interpreted to mean that he speaks of grave, but not of small, matter. From all this it is gathered, following Augustine, Thomas, Raymond, Antoninus, the Catechism of Trent, and Gerson, that he is guilty of perjury who does not fulfill what he promised under oath. But perjury is always a mortal sin.

VI. Our opinion is established by reasons. A promissory oath, as has been said, is distinguished from an assertory one in having for its matter the truth of the future execution of the promised and sworn thing. For, by reason of present truth, it is not distinguished from the assertory oath, as the adversaries themselves confess, who all concede that a promissory oath has a twofold truth, one concerning the present, the other concerning the future. This first proposition, then, is subject to no evasion. But when the sworn and promised matter is not fulfilled, this truth proper to a promissory oath is lacking. Therefore he who swears, and does not fulfill, commits perjury.

VII. The reason adduced is entirely... established from the words of St. Thomas, who, in express words, asserts that the matter of a promissory oath is the execution of the future promised thing, just as an assertory oath has for its matter truth concerning the past or the present. "Just as an assertory oath, which is about the past or the present, ought to have truth, so too the oath concerning things to be done by us in the future ought to have truth." The Angelic Doctor adds, however, that this oath lacks truth as often as the swearer does not, at the appointed time, fulfill the sworn matter. "For one is bound to make true that which he has sworn; otherwise TRUTH IS LACKING to the oath." If truth is lacking to the oath, then the swearer calls God to witness of falsity; therefore he perjures himself; therefore he sins mortally.

VIII. All this is confirmed. The reason why the defect of truth in an assertory oath, in the lightest matter, is always a mortal sin, is that God is brought forward as witness of falsity. But, as often as the promised matter sworn by a promissory oath is not fulfilled, God is brought forward as witness of falsity. Therefore the sin is mortal. Is not a promissory oath a true oath? Therefore it invokes God for the confirmation of truth: not, however, of present truth, since in this respect it is assertory; therefore it is brought forward for the confirmation of future truth; therefore, this truth being lacking, God is called to witness of falsity.

IX. Wondrous are the responses which the adversaries offer to these evident reasons. Cárdenas responds — and this is the common response (art. 1, n. 19) — in these words: "Although, in that case, it is false that the swearer will fulfill the oath (for God knows it is not to be fulfilled), this is nonetheless not false on the part of the swearer's intention, since he has the intention of fulfilling it. Whence it is only materially false." La Croix writes this same response. See where the sharp wits of these theologians finally come down! In an assertory oath we say that Peter swears materially false, when, having applied due diligence, he swears something false, thinking it to be true. But if, through his own fault, he is ignorant of the truth, he swears formally false, though he thinks it to be true. One who does not fulfill the sworn matter, does not fulfill it through his own fault. And this we suppose as certain. For if he did not fulfill it through true incapacity, then it would be materially false. But the adversaries all speak in the hypothesis that the swearer could, and deliberately does not wish to, fulfill what he promised. Therefore, since Cárdenas and others concede that the defect of this execution induces falsity, the falsity will be formal, not material — since it draws its origin from the deliberate and culpable will of the swearer himself, unwilling to fulfill the promise.

X. Our opinion is confirmed, finally, by this. All the adversaries concede, to a man, that one who does not fulfill, in grave matter, what he promised under oath, sins mortally against the promissory oath. All equally confess, to a man, that the formal reason of any oath whatsoever is drawn not from the gravity, or the smallness, of the sworn matter, but from the invocation of divine testimony; and for this reason, commonly, besides Castropalao, and a few others, they defend, as we have seen above, that all oaths are of the same species. Finally, all affirm that a promissory oath always includes what an assertory oath has, insofar as it ought to have present truth; but it is distinguished from the assertory in this, that it invokes God for the confirmation of future truth. All this is most certain among the adversaries themselves. From which I draw this valid proof: in the violation of a promise confirmed by oath and accepted, a twofold sin is committed, in my own opinion — one against justice, the other against the oath. Into this controversy the adversaries do not draw this proposition. But the sin which is against the oath is against truth: for one cannot sin against an oath, except by sinning against truth — since the formal reason of an oath is to confirm truth, whether present, future, or past. Therefore, that the matter be grave or light does not prevent the defect of truth from always inducing a mortal sin. The magnitude of the matter constitutes a sin grave against justice, or against the fidelity of the promise; and the smallness of the same matter induces only a venial sin against that same promise. But this is wrongly thrust in to increase or diminish the malice of the oath. For the oath takes its species from truth, and is rendered good or evil by truth or falsity. Now that this truth, the single matter of the oath, falls upon a grave or a light thing matters not at all to the formal reason of the oath. Which reasoning, since the adversaries admit it in an assertory oath, they ought also to admit in a promissory oath, since both are of the same species.

XI. Hence it seems that it can be inferred that the contrary opinion is comprehended under this condemned proposition: "To call God to witness to a light lie is not so great an irreverence as to warrant that one should be unwilling, or unable, to condemn a man for it." And indeed, as we have seen, the adversaries themselves do not know how to withdraw their own opinion from the thunderbolt of condemnation, except by fleeing to a material lie, to material falsity, or to a lie against future truth. But they are mistaken. For this alone is the difference between an assertory and a promissory oath, as has often been said: that the former looks to present or past truth, the latter to future truth; or, as the Angelic Doctor says above, the former falls upon the very act of swearing, the latter upon the thing which is sworn. Now, that the invocation of divine testimony in confirmation of present or past falsity should be a mortal sin, but not so in the attestation of future falsity — this is what seems to us nearly monstrous, especially since both falsity present and future are of the same species, just as the assertory and promissory oath are of the same species.

This opinion of ours is upheld, besides Augustine, Thomas, Raymond, the Catechism of Trent, and Gerson, by Cajetan (in his Summa, s.v. Periurium, ch. 3, and II-II, q. 89, art. 3), Candido (disq. 26, art. 10, dub. 3), Filliucci (tract. 25, ch. 10, §5), Valentia (I-II, q. 8, disp. 6, punct. 3, concl. ...), Toledo (in his Summa, Bk. IV, ch. 22), Covarrubias (Bk. 1, Variae, ch. 1, n. 2), Córdoba (in his Spanish Summa, q. 335), Filiarco (On the Office of the Priest, Vol. I, tit. III, Bk. III, ch. 3), Bassaeus (Vol. I and Vol. II, s.v. Iuramentum), Sayr (Bk. I, ch. 4, n. 15, and Bk. II, ch. 22, n. 79), Medina (in his Summa, ch. 14, §4), Lessius (On Justice and Law, Bk. II, ch. 42, dub. 3), Reginaldus (Bk. I, n. 79), Bonacina (Vol. II, disp. 4, q. 1, punct. 14, n. 16), Natalis Alexander (Bk. IV, art. 3, rule 3), Genet (tract. on the 1st precept of the Decalogue, ch. 11, q. 7), Henrique a Santo Ignazio (Vol. II, Bk. X, tit. 3, conf. 14), Paolo Gabriel Antoine (tract. on the theological virtues, ch. 4, q. 5), Wigandt (tract. 10, exam. 9, n. 41).

XII. You will object with this authority of St. Thomas (II-II, q. 110, art. 3, ad 5), where he writes this: "He who promises something, if he has the intention of doing what he promises, does not lie, because he does not speak against what he holds in his mind. If, however, he does not do what he promised, he will then seem to act unfaithfully, in that he changes his mind... Whence neither did the Apostle lie, who did not go to Corinth, whither he had promised he would go." It is astonishing that this authority could be thrust upon the adversaries — drawn from q. 110, where St. Thomas has not a single word concerning an oath; whereas St. Thomas himself opposes this same authority to himself in q. 89, where he treats the oath in ten articles. In the place first cited, he objects this authority to himself, in these words (art. 7): "It seems that an oath does not have the force of obligation. For an oath is brought in to confirm the truth of what is said. But when someone says something concerning the future, he speaks the truth, even if what he says does not come to pass — as Paul, although he did not proceed to Corinth, as he had said, nonetheless did not lie." What does the holy Doctor answer to this argument? Here are his own words: "To the first, then, it must be said that one act is of a simple word, another of an oath, in which divine testimony is implored. For, as regards the truth of a mere word, it suffices that someone say what he proposes to do — for this is already true in its cause, namely, in the resolve of the doer. But an oath ought not to be employed except in a matter of which someone is firmly certain. And therefore, if an oath is employed, on account of the reverence of the divine testimony which is invoked, man is obliged to make it true, according to his own possibility, that which he swore, as has been said. What if the outcome turns to the worse?" said the Angelic Doctor in the body of the article. "Truth is lacking to the oath, unless it be lacking on this ground alone: that the sworn matter is not fulfilled at the point of death (?) — otherwise truth is lacking to the oath." The response is so manifest that it needs no further explanation.

XIII. They object with these reasons, in like manner as... those which the Fathers of Salamanca advance, who, according to their custom, merely report the arguments of other authors. They philosophize otherwise, they say, concerning the truth of an assertory oath, and the truth of a promissory one, as regards present and future truth. For the defect of the former truth is a lie, which can be honored by no reasoning. But not to keep a promised matter, sworn under oath, is not a lie, but infidelity, though it admits a smallness of matter as regards the first defect of truth in the very deed; a smallness of matter can, however, be given as regards the second truth, respecting the intention of fulfilling it — since this second falsity is not truly a lie, but infidelity.

XIV. I have wished to present this single argument of theirs in the adversaries' own words, so that the weakness of the contrary opinion may thereby be more evident. It must be answered, then, that this argument is a mere paralogism, and contains contradictory extremes. They concede that the execution of the sworn thing is the future truth of a promissory oath, since, by reason of present truth, it is assertory. Then they add that falsity is not opposed to this truth, but infidelity. Why? Because that truth is future. But we say that these mutually conflict. For, once it is conceded that the execution of the promised thing is the truth of a promissory oath, it is wrongly added that falsity is not opposed to this truth, but infidelity — since falsity is opposed to every truth, whether present, future, or past. The adversaries' argumentation, then, labors under a paralogism, precisely because they do not distinguish between the promised thing, or a simple promise, and a promissory oath. The truth of a promise, as the Angelic Doctor most excellently declares, lies in the very resolve of the one promising, not in the future execution of the promised thing. For this reason, when someone, with a true resolve, promises that he will give something, he does not sin against truth — which is really supposed in the resolve — if he does not observe what he promised, but against fidelity. But when this promised thing constitutes the matter of an oath, it takes the place of a truth confirmed by the oath; and a promissory oath, precisely as such, falls solely upon this future truth, as the Angelic Doctor says, and as the adversaries themselves concede. It is futile, then, to say that the defect of that truth is infidelity, not falsity. We answer, then, by denying the antecedent of the fabricated argument. And we say that the defect of future truth in a promissory oath constitutes perjury, just as the defect of present or past truth in an assertory oath constitutes perjury.

It is astonishing that some Cárdenas has not explained the aforesaid condemned proposition, saying that to call God to witness of a light lie, against present truth, is a mortal sin of perjury; but not so, if he is called to witness against future truth. And indeed the adversaries will assign no true difference why a defect of past truth should constitute a formal lie, but a defect of future truth a merely material lie — except that the defect of that truth proceeds solely from the fault of the promiser.

XV. They object, second: One who does not fulfill a vow in a light matter does not sin mortally; therefore neither does one who does not fulfill an oath of a light matter. Response: The consequence is denied. For there is no grave injury, or irreverence, toward God in not rendering a light matter promised, which contributes little to his honor. But to invoke God as witness of falsity, even in the lightest matter, is a most grave injury against God — because one who swears falsely in whatever manner, so far as it depends on him, brings it about that God testifies to falsity. But the veracity of God cannot be reconciled with the falsity of any matter whatsoever, however light. Therefore one who does not execute a promised and sworn thing denies the veracity of God, and, by his own endeavor, destroys it.

False, then, is the contrary opinion, which is defended by Sotus (Bk. VIII, on justice, q. 1, art. 7), Suárez (Vol. II, on Religion, Bk. III, ch. 16), Sánchez (Bk. III, Summa, ch. 4, n. 23), Tamburini (ch. 3, n. 4), Pedro Ledesma (Vol. II, tract. 14, disp. 33), Azor (Bk. XI, ch. 5), Leander (tract. 1, disp. 7, q. 2), Castropalao (tract. 17, punct. 6, n. 8), Trullench (Bk. II, ch. 1, dub. 6, n. 6), Cárdenas (dissert. 17, ch. 2, art. 2), La Croix (Bk. III, part 1, ch. 2, dub. 5, n. 304), the theologians of Salamanca (tract. 17, ch. 2, punct. 5, §2, n. 53), and others among them, who also cite John of St. Thomas in their favor (II-II, q. 88, disp. 29, art. 8); but wrongly: for this author speaks there of a vow, in which he concedes a smallness of matter; and he only calls it a probable opinion concerning an oath, without at all defending it. To the cited authors may be added Fr. Sporer (tract. on the 2nd precept of the Decalogue, sect. ..., n. 137), where he says: "In practice, I hold it altogether safe that a promissory oath is excused from mortal sin by the lightness of the matter." But all the Fathers have execrated every perjury as an accursed thing, and Augustine calls it a monstrous beast; and none of them distinguished between promissory and assertory perjury. St. Thomas, however (II-II, q. 98, art. 3), resolves that all perjury is a mortal sin. Wherefore Fr. Sporer, too confidently, established that every promissory perjury is altogether safely reckoned venial, from the smallness of the matter. But of these things enough has been said.

XVI. Question IV. Would one who, under oath, promised something with a doubtful intention of fulfilling it, sin mortally? Response: All commonly respond affirmatively. Just as one who swears a doubtful matter as certain commits assertory perjury, so too one who promises something by oath which he doubts, or does not believe, he will fulfill, sins mortally by promissory perjury. No one, then, ought to confirm his promises by a promissory oath, unless he is morally certain of the future execution. Nor do probable conjectures, or reasons, suffice; but grave and firm foundations, which remove every prudent doubt, are required — whatever some may assert to the contrary. See what has been said concerning an assertory oath.

XVII. Question V. How are those oaths to be interpreted by which men commonly swear that they will not be the first to enter through a door, or to sit, etc.? Response: These are interpreted in this manner: that the swearers have the firm resolve of fulfilling what they assert, according to the sense which such expressions convey. The common sense, however, is that the swearer, so far as it concerns himself, so far as it lies on his own part, does not wish to enter first, to sit first, etc. Wherefore, if, by another's excessive courtesy, he is compelled to enter first...