Chapter VII — The divisions of oaths are given, and whether all oaths are of the same species is explained

I. The definition of the oath having been set forth, and the various formulas of swearing exhibited, it remains now that we present several divisions of oaths as well. St. Thomas, in the place cited (II-II, q. 89, art. 1), draws a twofold division of the oath: namely, from the side of the thing sworn, and from the manner of swearing.

II. From the side of the matter, or the thing which is sworn, an oath is divided into assertory and promissory. An assertory oath is that by which God is invoked to confirm the truth of an action, either present, or past, of the swearer himself; or concerning knowledge belonging to another person — as when witnesses swear that they know, or do not know, that another has perpetrated such a crime. If you say, "I swear that I did not commit this," it is an oath concerning something past. If you say, "I swear now that I do not know this present matter about which I am asked," it is an oath concerning something present. This assertory oath can also be made upon the veracity of an action, present or past, as when someone swears that he did not commit such a crime, or that he believes and professes the Catholic faith. If you say, "I swear that I committed that crime three days ago," Petro is invoked upon the truth of an action past, or present.

A promissory oath is that by which God is invoked, present or past, to confirm the promise of a future truth, so as to render another more secure — as, for example, when someone swears that he will give this money to another, or will do something else. Here are the words of St. Thomas himself: "Divine testimony is sometimes brought forward to assert things present or past, and this is called an assertory oath; but sometimes divine testimony is brought forward to confirm something future, and this is called a promissory oath."

That you may understand all this more clearly, attend to the following. In an assertory oath, what is always first regarded is present knowledge of the sworn matter. Wherefore, whether the action is present, or past, the truth subject to the oath is always present in the mind of the swearer himself. In a promissory oath there is always included an assertion of present truth; for one who swears that he will do something first calls God to witness that he presently has the resolve, or will, of doing what he promises; second, he invokes God as a surety of future truth — namely, that he will fulfill, and carry into execution, the thing promised. Nor is this division superfluous; for, although a promissory oath includes an assertory one, the reverse is not true. When someone swears something to be performed in the future by another — say, "I swear that Peter will enter religious life" — this is not a promissory but an assertory oath; for I swear that I presently know that Peter will embrace the religious state. Whoever swears in this manner ought to have vehement and most grave reasons for so testifying; otherwise the oath would be made rashly.

A promissory oath is also customarily divided into absolute, or simple, whereby someone absolutely swears that he will do something; and confirmatory, whereby, that is, either a vow to be made to God, joined with a man, is confirmed, and is called a sworn pact; or a promise made to God and man simultaneously — as when you promise, with an oath, to give money to such a poor person, who accepts your promise; and this is called a vow sworn with a pact. The one who violates it contracts a twofold, or threefold, malice. For one who violates a vow sworn to God sins both against the vow, and against the oath — that is, by a twofold sin against the virtue of religion. But one who does not fulfill a vow made to God, and afterward confirmed by oath both to God and to man, besides the twofold malice against religion, violates the fidelity owed to God, and to man, and at the same time commits a sin of injustice against the man to whom the promise was made.

III. From the side of the manner, or the formula of pronouncing it, an oath is distinguished into contestatory, which consists in a simple attestation, or invocation, of divine testimony — as when it is simply said, "I swear by God that it is so" — and into execratory, whereby God is invoked, not only as the infallible witness of truth, but also as the avenger of falsehood. This latter oath, however, can be conceived and uttered in a threefold formula.

First, when someone, at the point of death, and expressly, invokes evil upon himself from God, to be inflicted — for example, when he says, "May God do this to me, and may he add this." In canon law the formula which formerly commonly prevailed was of this kind: "May God help me," etc. That formula which now prevails is: "So help me God, and these Holy Gospels." This execration is most grave; for it yields this sense: "May God not help me, if what I pronounce is false."

Second, when someone swears... , imprecating upon himself some evil to be inflicted by a creature, God so permitting — as when one says, "May lightning strike me," "may the devil seize me," "may the earth swallow me," "may I die a sudden death," etc. In these imprecations, however, for the oath to be a true one, it is necessary that the swearer have regard to God, and invoke him as the avenger permitting such things. For if someone merely imprecated evil upon himself, with no regard to God at all, he would not utter an oath. Third, one can swear by the health, or life, of one's children, of one's Prince, of Caesar, etc., whose sense is: "May the health of my children perish, may the life of my parents, of my Prince, of Caesar perish, if what I say is not so." Holy men, even under the Old and New Testament, sometimes made use of execratory oaths. Joseph swore in this manner (Genesis 42:15): "By the health of Pharaoh, you shall not go forth hence." St. Paul swore upon his own soul: "I call God to witness upon my soul" (2 Corinthians 1). By execration David likewise swore: "If I have rendered to them that repaid me evils, let me deservedly fall empty before my enemies" (Psalm 7). In the commentary on this Psalm, Augustine writes this: "He seems to swear by execration, which is a most grave kind of swearing, when a man says: 'If I did that, let this befall me.'" It should be noted that, when an execratory oath is uttered by the health, or life, of other persons, these persons ought to belong to the swearer by some title — as is clear in the examples adduced, of parents, Prince, Caesar, children, wife, etc. Wherefore, when someone says, "May an arrow pierce me, unless I have spoken the truth," he utters a curse, not an oath.

IV. Again, from the side of the form, an oath is divided into simple and solemn. Simple oaths are those made by private men, according to whatever rites of law or custom please them most. The pagans had innumerable rites of swearing, concerning which consult Alessandro Alessandri, Bk. V, Genial Days, ch. 10. The Jews too observed several rites in the use of an oath. The more celebrated were the raising of the hands (Genesis 14:22): "I lift up my hand to the Lord the most high God"; likewise passing between the two parts of a slain calf, or of any victim: "the calf, which they had cut in two, and passed between the parts thereof" (Jeremiah 34:18). But a more solemn rite was that of placing one's hand under the thigh of him who exacted the oath. By this rite Abraham exacted an oath from his elder servant: "Put thy hand under my thigh" (Genesis 24:2). By this same rite, too, Jacob, near death, asked his son Joseph: "If I have found favor in thy sight, put thy hand under my thigh" (Genesis 47:29). On this ceremony there are various opinions of the Fathers and interpreters. Setting others aside, the more common is that which Jerome relates in his Hebrew Questions — namely, that by that sign it was indicated that the oath was confirmed by that which was contained in the loins of Abraham and Jacob, namely, faith in Christ, who, as Paul says (Hebrews 7), was contained in the loins of Abraham. And indeed we do not read that this ceremony was employed by anyone else besides Abraham and Jacob.

V. Likewise, in our own times, various rites are prescribed for solemn oaths, both in civil law, and in canon law. The more common rite is seen in touching sacred things — such as the Gospels, relics, and even the most sacred Eucharist. In the civil forum they are accustomed to touch the royal scepter, or to raise the first fingers. If you wish to know the various solemnities of that forum customarily observed in an oath, consult the law "Generaliter," last, on things entrusted, in the Code. Formerly, the solemn and common rite of Christians was contact with the altar, or with the sacred table, which rite was also observed in private oaths. Chrysostom speaks of this oath (Homily 15 to the people): "When you swear upon the sacred table, where the immaculate Christ is placed, you sacrifice your brother... at least reverence that Book which you hold out for the oath."

VI. A solemn oath is threefold, or is customarily made in three ways. The first is verbal only, which is made in words alone, and in the words themselves a certain fixed form is observed — as when an oath is made by an express invocation of God, of the Most Holy Virgin, or of the other Saints. The second is real only, and is called a real oath, made by a single external sign, by touch, gesture, or nod — say, by contact with the Gospels, of the Cross, of the altar, etc. — with no words at all employed. The third oath is called mixed, which is made both by words and by contact with a sacred thing. An oath, then, can be made either by words alone, and is called verbal; or by signs alone, without words (for words are not necessary for oaths), and is called real; or finally by both words and signs together, and is called mixed, or even corporeal, because, besides words, a corporeal action is furthermore employed.

VII. Solemn oaths are also customarily judicial — namely, those which are rendered in courts of law — and are of various kinds, as I shall say. The first judicial oath is that which is made at the beginning of a lawsuit, and is called the oath of calumny, whereby the plaintiff must swear that he brought the suit not with the intent of calumny, but solely for the sake of the truth of the cause; and the defendant must likewise swear that he believes he has a just reason for resisting. The Emperor Justinian (law 2, Code, on the law of oaths, preamble) introduced this custom of swearing, so as to draw litigants away from the calumnious pursuit of lawsuits. And, to make this more effective, he took away from all judges the power of remitting this oath, in these words (in the place cited, §4): "But since we fear lest perhaps certain persons, using some collusion, should seem to remit such an oath among themselves, and, by this dissimulation, mock our sanction, we ordain that all judges, even those judging by compromise, exercising their own force (since we have set forth the present law not for the advantage of private persons, but for the common utility), by no means suffer such an oath to be remitted." He adds the reason (§8): "For thus not only lawsuits, but also calumniators, will be diminished." This use of the oath flourished for many centuries; but now it has become entirely obsolete in the courts of Princes, as authors commonly note. Maranta gives the reason for its disuse (On Judicial Order, Part VI, tit. on the oath, n. 11), in these words: "Whence I think that the litigants of our time swear rather to commit calumny than to avoid it; and therefore it would be better if it were entirely removed from judicial proceedings, for the sake of avoiding so many perjuries." This oath of calumny, which is made at the beginning of a lawsuit, is called the oath of belief, distinguished from the oath of truth. Julius Paulus gives this distinction, a jurist celebrated among both civil and canon lawyers, in his Introductory Remarks on Bk. II of the Code, tit. 58: "The third, preparatory (he says), is good faith, which the law requires of litigants, so that they may not litigate rashly. Wherefore it commands both the plaintiff and the defendant to swear an oath of calumny... Note that this oath is [as our writers say] of belief, not of truth. For litigants do not swear that they have a good cause, but that they so believe." This distinction is material. For the proximate matter of an oath, even of belief, is truth — since it is true that one so believes, namely, that one has a good cause.

VIII. The second judicial oath is called the oath in the progress of the lawsuit, which is given by the judge to the parties, as often as it seems good to him; this oath is now also called the oath of malice, whereby litigants swear that they are not seeking, nor will accept, extraordinary delays for the purpose of calumny. The use of this oath of malice still flourishes in many secular courts, as to certain articles or propositions. The judge, at the instance of a party, denies, or grants, this oath, according as he judges it opportune. In ecclesiastical courts, however, the use of this oath is very frequent, concerning which the Canonists are to be consulted.

IX. The third judicial oath is called the supplementary oath, whereby the want of proofs is supplied — that is, when proofs are lacking, an oath is substituted, as the last remedy for settling lawsuits and controversies. For the end of an oath is the manifestation of a doubtful truth. Wherefore, when the truth in controversies cannot be discerned by proofs, or witnesses, the Apostle himself assigns the oath as fit to be employed for confirmation, and for settling the dispute: "An oath for confirmation is the end of all their controversy" (Hebrews 6). This oath, in civil cases, is called the supplementary oath; in criminal cases, it is called the purgatory oath.

X. The fourth judicial oath is called the oath "in litem" [as to the matter at issue], which is threefold. One is assigned to prove the value... and quantity of a thing lost through another's fraud — for example, if you deposited a chest with an innkeeper, or with another for safekeeping, and, the seals having been broken, it is restored to you damaged, and there is a grave presumption of the innkeeper's, or depositary's, fraud, or if you have suffered a loss from a thief, the theft being proven, the price of the thing taken away is settled by oath. This oath is called by jurists the oath of truth. The second is called the oath of affection, when your property, through another's fault, has been lost, or destroyed, and it is granted to you, by oath, to estimate the price of that thing which you reckoned most useful and convenient — in which, lest you exceed double the common value, it is forbidden; and therefore this oath is subject to the judge's determination. The third is called the oath upon a particular interest, and this is subject to matter extraneous to the thing itself, and to your own reputation — for example, if you deposited your money with a depositary at your own discretion, to be restored to you, and the depositary, through his own fault, did not restore the money at the agreed time, on account of which you suffered a loss, and the loss of gain — it is permitted to you, in this case, your own oath being interposed, to estimate the loss to which you have been subjected (law "Nummis," on the exaction of oaths). What has been said of money must likewise be said of other things in which you may have suffered a loss, or damage, through the fraud of a depositary.

XI. Finally, a judicial oath is called, on one hand, necessary, and, on the other, voluntary. That is called necessary which, in a doubtful cause, on account of the want of grounds by which to settle the lawsuit, the judge tenders, either of his own office, or a party urging it. It is called necessary both because the judge is sometimes compelled to tender it, and because it cannot be refused, without just cause, by the party to whom it is tendered. Then the plaintiff has cause for declining the oath, when he has evidently demonstrated his own intention; the defendant, however, if he confesses forgetfulness of the cause. That oath is called voluntary which a party tenders to the other party, and can be avoided. When, however, it is tendered, the judge approving, it becomes in a certain way necessary — since he to whom it was tendered ought to swear, unless he has a just cause for refusing; otherwise the cause falls. So that ignorance of the terms may not cause confusion, the difference between "to tender" and "to retender" is this: he is said to tender an oath who first offers it. When a party refuses it, and offers it to his adversary, he is said to retender it.

XII. Jurists dispute on both sides whether, in a doubtful cause, the oath which is called supplementary ought to be tendered to the defendant or to the plaintiff. And, although opinions vary, the more common opinion is that the oath ought to be tendered to the defendant, absolutely speaking, and not to the plaintiff — since laws are more inclined to acquit than to condemn. And indeed, if the widest access to a supplementary oath were opened to the plaintiff, so that he might settle his own cause at will, the necessity of proofs would be removed; and consequently a most ample path would be opened for false accusations of persons contending, and for perjuries. The qualities, however, and circumstances of the lawsuit are always to be seriously weighed by the judge, so that he may tender the oath to that party, whether plaintiff or defendant, to whom he perceives the reasons or presumptions more favorable.

XIII. This all grave authors greatly impress: namely, that this oath which they call supplementary is to be employed only in the most grave necessity. Antoine Favre (Bk. IV, tit. 1, def. 1, note 9, on the Code) absolutely disapproves this supplementary oath, and calls its use an inveterate error. But Favre's opinion is erroneous — since St. Paul, for the settling of controversies, necessity compelling, declares this oath to be useful. This alone must be kept before one's eyes: that it be tendered with the utmost circumspection and caution, so as to remove the occasion of perjury. For very many men, religion held in contempt, are ready to swear falsely; some, however, are timid even to the point of superstition (though these are few), and dare not swear at all.

XIV. Authors likewise teach that, in criminal cases in which a corporal penalty is to be inflicted on the defendant, there is no room for a supplementary oath — since, in these cases, proofs clearer than light are required (law "Sciant cuncti," on proofs, in the Code). In civil actions, too, of an infamous nature, authors commonly hand down that one must abstain from tendering this oath. An action is called infamous which, when known, inflicts grave infamy on the defendant — such as clandestine theft. If, however, grave reasons press, it can be tendered. Van Espen (Bk. V, tit. ..., ch. 8, n. 19) absolutely denies that an oath ought to be tendered to one summoned by an infamous action, and alleges the authority of Gregory IX (tit. on the law of oaths, final ch.), where the Pontiff says: "Let it not be lawful for one summoned by an infamous action to retender such an oath to..." This authority clearly opposes Van Espen's own assertion — for the Pontiff forbids the defendant to retender the oath. Therefore he supposes it lawful for it to be tendered to him. In this action, then, as has been said, just as in non-infamous cases, the judge, in no way suspect, is required; but in arduous cases, such as a matrimonial cause, more than semi-full proof is required, one not subject to exception; and the presumption, above all, ought to favor the party to whom the oath is tendered, rather than to be retendered, or thrown back, upon the plaintiff. For sometimes, one summoned by an infamous action, an oath can be tendered against the defendant, if it prevails. In non-infamous, and non-arduous, cases, semi-full proof suffices — namely, a single witness, not subject to exception, for the judge to be able to tender the oath. But enough of judicial oaths, since their treatment does not pertain to our present undertaking.

XV. The various divisions of oaths having been explained, it remains to inquire whether these oaths are of the same species, whether assertory or execratory, whether by... Castropalao (Vol. III, tract. 14, disp. 1, punct. 1, n. 7) briefly discusses these species. Suárez (Bk. I, ch. 9, n. 4) defends the same opinion as very probable, and produces sufficiently probable reasons, and resolves the opposing arguments validly.

The more common opinion is that all oaths are of the same species, whether promissory, or assertory, whether imprecatory, whether they are made by God, or by creatures, or by contact with the Gospel, or by any other solemnity.

XVI. The patrons of this opinion adduce a most valid reason. Since the primary and essential notion of any oath whatsoever is the invocation of divine testimony in confirmation of truth. Now whether this truth be present or past; whether the aforesaid invocation be made by simple contestation, or by execration; whether one expressly names God, or tacitly, insofar as he shines forth in creatures — none of this varies the formal reason of the oath in any way, since God is called to witness. There is, then, only an accidental and material diversity. And although in a promissory oath God is invoked not only as witness of present truth, but also as surety of future truth — that is, of the execution of the thing promised and confirmed by oath — just as in an execratory oath he is invoked as witness and, at the same time, as avenger — nonetheless these grounds are not such as to introduce a specific diversity among oaths, for the reason already given: because the formal reason from which an oath derives its nature, or essential notion, is the invocation of divine testimony. Wherefore, since this is the same in all oaths, and does not vary according to the various formulas by which oaths are uttered, all oaths ought therefore to be reckoned of one and the same species.

XVII. There is no need to spend time in a longer discussion of this controversy. For, if we remain within the bounds of metaphysical reasoning, each opinion enjoys its own probability. In the general run of moral practice, however, one oath induces a certain greater obligation than another: for the more solemn the formulas in which the oath is conceived, the graver too is the malice with which its violation is stained, as the Angelic Doctor teaches (II-II, q. 98, art. 3, ad 2): "It is a graver sin, if someone swears solemnly by the Gospel, than if he swears by God in common speech, both on account of the scandal, and on account of the greater deliberation." These things being equally weighed on both sides, it is graver, if one swearing by God perjures himself, than if one swearing by the Gospel perjures himself.

XVIII. It is certain, then, among all, that some perjuries betray a graver malice, at least within the same species. But according to the other opinion, which asserts that promissory and assertory oaths differ in species, the malice too of one perjury differs in species from another. Wherefore, according to this opinion, it will be necessary to explain the species of the oath in confession. According to the first opinion, however, the circumstance which is greatly aggravating the malice will likewise have to be manifested, as we shall demonstrate in its proper place, though several more recent Doctors say the opposite.

XIX. Oaths are not infrequently affected by a different morality, whether as to line, or genus. For if someone swore, "May God perish, if it is not so," besides the malice of the oath, there would be the malice of blasphemy. Again, if you did not disclose the truth to a superior judge legitimately requiring it, under oath, you would contract a twofold malice: one of perjury, the other of disobedience. Finally, if in judgment you swore something to another's harm, you would perpetrate a threefold sin — namely, of perjury, of disobedience, and of injustice.