Thomas Aquinas, Summa Theologica. Secunda Secundæ Partis: Justice – Q.s 89; 90; 98: On Oaths; Adjuration and Perjury.

Thomas Aquinas, Summa Theologica. Secunda Secundæ Partis: Justice – Q.s 89; 90; 98: On Oaths; Adjuration and Perjury.

Source: Thomas Aquinas. 1920. The “Summa Theologica” of St. Thomas Aquinas . Second and Revised Edition. Edited by Roy J Deferrari and M. Iviolata Barry. Translated by Dominicans. 5 vols. London: Burns, Oates & Washbourne Ltd. Online Edition 2008 by Kevin Knight, New Advent.

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Question 89. Oaths

Article 1. Whether to swear is to call God to witness?

Objection 1. It would seem that to swear is not to call God to witness. Whoever invokes the authority of Holy Writ calls God to witness, since it is His word that Holy Writ contains. Therefore, if to swear is to call God to witness, whoever invoked the authority of Holy Writ would swear.

But this is false Therefore the antecedent is false also.

Objection 2. Further, one does not pay anything to a person by calling him to witness. But he who swears by God pays something to Him for it is written (Matthew 5:33): "Thou shall pay [Douay: 'perform'] thy oaths to the Lord"; and Augustine says [Serm. clxxx] that to swear [jurare] is "to pay the right [jus reddere] of truth to God." Therefore to swear is not to call God to witness.

Objection 3. Further, the duties of a judge differ from the duties of a witness, as shown above (Q67,70). Now sometimes a man, by swearing, implores the Divine judgment, according to Psalm 7:5, "If I have rendered to them that repaid me evils, let me deservedly fall empty before my enemies." Therefore to swear is not to call God to witness.

On the contrary, Augustine says in a sermon on perjury (Serm. clxxx): "When a man says: 'By God,' what else does he mean but that God is his witness?"

I answer that, As the Apostle says (Hebrews 6:16), oaths are taken for the purpose of confirmation. Now speculative propositions receive confirmation from reason, which proceeds from principles known naturally and infallibly true. But particular contingent facts regarding man cannot be confirmed by a necessary reason, wherefore propositions regarding such things are wont to be confirmed by witnesses. Now a human witness does not suffice to confirm such matters for two reasons. First, on account of man's lack of truth, for many give way to lying, according to Psalm 16:10, "Their mouth hath spoken lies [Vulgate: 'proudly']." Secondly, on account of this lack of knowledge, since he can know neither the future, nor secret thoughts, nor distant things: and yet men speak about such things, and our everyday life requires that we should have some certitude about them. Hence the need to have recourse to a Divine witness, for neither can God lie, nor is anything hidden from Him. Now to call God to witness is named "jurare" [to swear] because it is established as though it were a principle of law [jure] that what a man asserts under the invocation of God as His witness should be accepted as true. Now sometimes God is called to witness when we assert present or past events, and this is termed a "declaratory oath"; while sometimes God is called to witness in confirmation of something future, and this is termed a "promissory oath."

But oaths are not employed in order to substantiate necessary matters, and such as come under the investigation of reason; for it would seem absurd in a scientific discussion to wish to prove one's point by an oath.

Reply to Objection 1. It is one thing to employ a Divine witness already given, as when one adduces the authority of Holy Scripture; and another to implore God to bear witness, as in an oath.

Reply to Objection 2. A man is said to pay his oaths to God because he performs what he swears to do, or because, from the very fact that he calls upon God to witness, he recognizes Him as possessing universal knowledge and unerring truth.

Reply to Objection 3. A person is called to give witness, in order that he may make known the truth about what is alleged. Now there are two ways in which God makes known whether the alleged facts are true or not. On one way He reveals the truth simply, either by inward inspiration, or by unveiling the facts, namely, by making public what was hitherto secret: in another way by punishing the lying witness, and then He is at once judge and witness, since by punishing the liar He makes known his lie. Hence oaths are of two kinds: one is a simple contestation of God, as when a man says "God is my witness," or, "I speak before God," or, "By God," which has the same meaning, as Augustine states [See argument On the contrary]; the other is by cursing, and consists in a man binding himself or something of his to punishment if what is alleged be not true.

Article 2. Whether it is lawful to swear?

Objection 1. It would seem that it is not lawful to swear. Nothing forbidden in the Divine Law is lawful. Now swearing is forbidden (Matthew 5:34), "But I say to you not to swear at all"; and (James 5:12), "Above all things, my brethren, swear not." Therefore swearing is unlawful.

Objection 2. Further, whatever comes from an evil seems to be unlawful, because according to Matthew 7:18, "neither can an evil tree bring forth good fruit." Now swearing comes from an evil, for it is written (Matthew 5:37): "But let your speech be: Yea, yea: No, no. And that which is over and above these is of evil." Therefore swearing is apparently unlawful.

Objection 3. Further, to seek a sign of Divine Providence is to tempt God, and this is altogether unlawful, according to Deuteronomy 6:16, "Thou shalt not tempt the Lord thy God." Now he that swears seems to seek a sign of Divine Providence, since he asks God to bear witness, and this must be by some evident effect. Therefore it seems that swearing is altogether unlawful.

On the contrary, It is written (Deuteronomy 6:13): "Thou shalt fear the Lord thy God . . . and shalt swear by His name."

I answer that, Nothing prevents a thing being good in itself, and yet becoming a source of evil to one who makes use thereof unbecomingly: thus to receive the Eucharist is good, and yet he that receives it "unworthily, eateth and drinketh judgment to himself" (1 Corinthians 11:29). Accordingly in answer to the question in point it must be stated that an oath is in itself lawful and commendable. This is proved from its origin and from its end. From its origin, because swearing owes its introduction to the faith whereby man believes that God possesses unerring truth and universal knowledge and foresight of all things: and from its end, since oaths are employed in order to justify men, and to put an end to controversy (Hebrews 6:16).

Yet an oath becomes a source of evil to him that makes evil use of it, that is who employs it without necessity and due caution. For if a man calls God as witness, for some trifling reason, it would seemingly prove him to have but little reverence for God, since he would not treat even a good man in this manner. Moreover, he is in danger of committing perjury, because man easily offends in words, according to James 3:2, "If any man offend not in word, the same is a perfect man." Wherefore it is written (Sirach 23:9): "Let not thy mouth be accustomed to swearing, for in it there are many falls."

Reply to Objection 1. Jerome, commenting on Matthew 5:34, says: "Observe that our Saviour forbade us to swear, not by God, but by heaven and earth. For it is known that the Jews have this most evil custom of swearing by the elements." Yet this answer does not suffice, because James adds, "nor by any other oath." Wherefore we must reply that, as Augustine states (De Mendacio xv), "when the Apostle employs an oath in his epistles, he shows how we are to understand the saying, 'I say to you, not to swear at all'; lest, to wit, swearing lead us to swear easily and from swearing easily, we contract the habit, and, from swearing habitually, we fall into perjury. Hence we find that he swore only when writing, because thought brings caution and avoids hasty words."

Reply to Objection 2. According to Augustine (De Serm. Dom. in Monte i. 17): "If you have to swear, note that the necessity arises from the infirmity of those whom you convince, which infirmity is indeed an evil. Accordingly He did not say: 'That which is over and above is evil,' but 'is of evil.' For you do no evil; since you make good use of swearing, by persuading another to a useful purpose: yet it 'comes of the evil' of the person by whose infirmity you are forced to swear."

Reply to Objection 3. He who swears tempts not God, because it is not without usefulness and necessity that he implores the Divine assistance. Moreover, he does not expose himself to danger, if God be unwilling to bear witness there and then: for He certainly will bear witness at some future time, when He "will bring to light the hidden things of darkness, and will make manifest the counsels of hearts" (1 Corinthians 4:5). And this witness will be lacking to none who swears, neither for nor against him.

Article 3. Whether three accompanying conditions of an oath are suitably assigned, namely, justice, judgment, and truth?

Objection 1. It would seem that justice, judgment and truth are unsuitably assigned as the conditions accompanying an oath. Things should not be enumerated as diverse, if one of them includes the other. Now of these three, one includes another, since truth is a part of justice, according to Tully (De Invent. Rhet. ii, 53): and judgment is an act of justice, as stated above (Question 60, Article 1). Therefore the three accompanying conditions of an oath are unsuitably assigned.

Objection 2. Further, many other things are required for an oath, namely, devotion, and faith whereby we believe that God knows all things and cannot lie. Therefore the accompanying conditions of an oath are insufficiently enumerated.

Objection 3. Further, these three are requisite in man's every deed: since he ought to do nothing contrary to justice and truth, or without judgment, according to 1 Timothy 5:21, "Do nothing without prejudice," i.e. without previous judgment [Vulgate: 'Observe these things without prejudice, doing nothing by declining to either side.']. Therefore these three should not be associated with an oath any more than with other human actions.

On the contrary, It is written (Jeremiah 4:2): "Thou shalt swear: As the Lord liveth, in truth, and in judgment, and in justice": which words Jerome expounds, saying: "Observe that an oath must be accompanied by these conditions, truth, judgment and justice."

I answer that, As stated above (Article 2), an oath is not good except for one who makes good use of it. Now two conditions are required for the good use of an oath. First, that one swear, not for frivolous, but for urgent reasons, and with discretion; and this requires judgment or discretion on the part of the person who swears. Secondly, as regards the point to be confirmed by oath, that it be neither false, nor unlawful, and this requires both truth, so that one employ an oath in order to confirm what is true, and justice, so that one confirm what is lawful. A rash oath lacks judgment, a false oath lacks truth, and a wicked or unlawful oath lacks justice.

Reply to Objection 1. Judgment does not signify here the execution of justice, but the judgment of discretion, as stated above. Nor is truth here to be taken for the part of justice, but for a condition of speech.

Reply to Objection 2. Devotion, faith and like conditions requisite for the right manner of swearing are implied by judgment: for the other two regard the things sworn to as stated above. We might also reply that justice regards the reason for swearing.

Reply to Objection 3. There is great danger in swearing, both on account of the greatness of God Who is called upon to bear witness, and on account of the frailty of the human tongue, the words of which are confirmed by oath. Hence these conditions are more requisite for an oath than for other human actions.

Article 4. Whether an oath is an act of religion or latria?

Objection 1. It would seem that an oath is not an act of religion, or latria. Acts of religion are about holy and divine things. But oaths are employed in connection with human disputes, as the Apostle declares (Hebrews 6:16). Therefore swearing is not an act of religion or latria.

Objection 2. Further, it belongs to religion to give worship to God, as Tully says (De Invent. Rhet. ii, 53). But he who swears offers nothing to God, but calls God to be his witness. Therefore swearing is not an act of religion or latria.

Objection 3. Further, the end of religion or latria is to show reverence to God. But the end of an oath is not this, but rather the confirmation of some assertion. Therefore swearing is not an act of religion.

On the contrary, It is written (Deuteronomy 6:13): "Thou shalt fear the Lord thy God, and shalt serve Him only, and thou shalt swear by His name." Now he speaks there of the servitude of religion. Therefore swearing is an act of religion.

I answer that, As appears from what has been said above (Article 1), he that swears calls God to witness in confirmation of what he says. Now nothing is confirmed save by what is more certain and more powerful. Therefore in the very fact that a man swears by God, he acknowledges God to be more powerful, by reason of His unfailing truth and His universal knowledge; and thus in a way he shows reverence to God. For this reason the Apostle says (Hebrews 6:16) that "men swear by one greater than themselves," and Jerome commenting on Matthew 5:34, says that "he who swears either reveres or loves the person by whom he swears." The Philosopher, too, states (Metaph. i, 3) that "to swear is to give very great honor." Now to show reverence to God belongs to religion or latria. wherefore it is evident that an oath is an act of religion or latria.

Reply to Objection 1. Two things may be observed in an oath. The witness adduced, and this is Divine: and the thing witnessed to, or that which makes it necessary to call the witness, and this is human. Accordingly an oath belongs to religion by reason of the former, and not of the latter.

Reply to Objection 2. In the very fact that a man takes God as witness by way of an oath, he acknowledges Him to be greater: and this pertains to the reverence and honor of God, so that he offers something to God, namely, reverence and honor.

Reply to Objection 3. Whatsoever we do, we should do it in honor of God: wherefore there is no hindrance, if by intending to assure a man, we show reverence to God. For we ought so to perform our actions in God's honor that they may conduce to our neighbor's good, since God also works for His own glory and for our good.

Article 5. Whether oaths are desirable and to be used frequently as something useful and good?

Objection 1. It would seem that oaths are desirable and to be used frequently as something useful and good. Just as a vow is an act of religion, so is an oath. Now it is commendable and more meritorious to do a thing by vow, because a vow is an act of religion, as stated above (Question 88, Article 5). Therefore for the same reason, to do or say a thing with an oath is more commendable, and consequently oaths are desirable as being good essentially.

Objection 2. Further, Jerome, commenting on Matthew 5:34, says that "he who swears either reveres or loves the person by whom he swears." Now reverence and love of God are desirable as something good essentially. Therefore swearing is also.

Objection 3. Further, swearing is directed to the purpose of confirming or assuring. But it is a good thing for a man to confirm his assertion. Therefore an oath is desirable as a good thing.

On the contrary, It is written (Sirach 23:12): "A man that sweareth much shall be filled with iniquity": and Augustine says (De Mendacio xv) that "the Lord forbade swearing, in order that for your own part you might not be fond of it, and take pleasure in seeking occasions of swearing, as though it were a good thing."

I answer that, Whatever is required merely as a remedy for an infirmity or a defect, is not reckoned among those things that are desirable for their own sake, but among those that are necessary: this is clear in the case of medicine which is required as a remedy for sickness. Now an oath is required as a remedy to a defect, namely, some man's lack of belief in another man. Wherefore an oath is not to be reckoned among those things that are desirable for their own sake, but among those that are necessary for this life; and such things are used unduly whenever they are used outside the bounds of necessity. For this reason Augustine says (De Serm. Dom. in Monte i, 17): "He who understands that swearing is not to be held as a good thing," i.e. desirable for its own sake, "restrains himself as far as he can from uttering oaths, unless there be urgent need."

Reply to Objection 1. There is no parity between a vow and an oath: because by a vow we direct something to the honor of God, so that for this very reason a vow is an act of religion. On the other hand, in an oath reverence for the name of God is taken in confirmation of a promise. Hence what is confirmed by oath does not, for this reason, become an act of religion, since moral acts take their species from the end.

Reply to Objection 2. He who swears does indeed make use of his reverence or love for the person by whom he swears: he does not, however, direct his oath to the reverence or love of that person, but to something else that is necessary for the present life.

Reply to Objection 3. Even as a medicine is useful for healing, and yet, the stronger it is, the greater harm it does if it be taken unduly, so too an oath is useful indeed as a means of confirmation, yet the greater the reverence it demands the more dangerous it is, unless it be employed aright; for, as it is written (Sirach 23:13), "if he make it void," i.e. if he deceive his brother, "his sin shall be upon him: and if he dissemble it," by swearing falsely, and with dissimulation, "he offendeth double," [because, to wit, "pretended equity is a twofold iniquity," as Augustine [Enarr. in Psalm 63:7] declares: "and if he swear in vain," i.e. without due cause and necessity, "he shall not be justified."

Article 6. Whether it is lawful to swear by creatures?

Objection 1. It would seem that it is not lawful to swear by creatures. It is written (Matthew 5:34-36): "I say to you not to swear at all, neither by heaven . . . nor by the earth . . . nor by Jerusalem . . . nor by thy head": and Jerome, expounding these words, says: "Observe that the Saviour does not forbid swearing by God, but by heaven and earth," etc.

Objection 2. Further, punishment is not due save for a fault. Now a punishment is appointed for one who swears by creatures: for it is written (22, qu. i, can. Clericum): "If a cleric swears by creatures he must be very severely rebuked: and if he shall persist in this vicious habit we wish that he be excommunicated." Therefore it is unlawful to swear by creatures.

Objection 3. Further, an oath is an act of religion, as stated above (Article 4).

But religious worship is not due to any creature, according to Romans 1:23-25. Therefore it is not lawful to swear by a creature.

On the contrary, Joseph swore "by the health of Pharaoh" (Genesis 42:16). Moreover it is customary to swear by the Gospel, by relics, and by the saints.

I answer that, As stated above (1, ad 3), there are two kinds of oath. One is uttered a simple contestation or calling God as witness: and this kind of oath, like faith, is based on God's truth. Now faith is essentially and chiefly about God Who is the very truth, and secondarily about creatures in which God's truth is reflected, as stated above (Question 1, Article 1). On like manner an oath is chiefly referred to God Whose testimony is invoked; and secondarily an appeal by oath is made to certain creatures considered, not in themselves, but as reflecting the Divine truth. Thus we swear by the Gospel, i.e. by God Whose truth is made known in the Gospel; and by the saints who believed this truth and kept it.

The other way of swearing is by cursing and in this kind of oath a creature is adduced that the judgment of God may be wrought therein. Thus a man is wont to swear by his head, or by his son, or by some other thing that he loves, even as the Apostle swore (2 Corinthians 1:23), saying: "I call God to witness upon my soul."

As to Joseph's oath by the health of Pharaoh this may be understood in both ways: either by way of a curse, as though he pledged Pharao's health to God; or by way of contestation, as though he appealed to the truth of God's justice which the princes of the earth are appointed to execute.

Reply to Objection 1. Our Lord forbade us to swear by creatures so as to give them the reverence due to God. Hence Jerome adds that "the Jews, through swearing by the angels and the like, worshipped creatures with a Divine honor."

In the same sense a cleric is punished, according to the canons (22, qu. i, can. Clericum, Objection 2), for swearing by a creature, for this savors of the blasphemy of unbelief. Hence in the next chapter, it is said: "If any one swears by God's hair or head, or otherwise utter blasphemy against God, and he be in ecclesiastical orders, let him be degraded."

This suffices for the Reply to the Second Objection.

Reply to Objection 3. Religious worship is shown to one whose testimony is invoked by oath: hence the prohibition (Exodus 23:13): "By the name of strange gods you shall not swear." But religious worship is not given to creatures employed in an oath in the ways mentioned above.

Article 7. Whether an oath has a binding force?

Objection 1. It would seem that an oath has no binding force. An oath is employed in order to confirm the truth of an assertion. But when a person makes an assertion about the future his assertion is true, though it may not be verified. Thus Paul lied not (2 Corinthians 1:15, seqq.) though he went not to Corinth, as he had said he would (1 Corinthians 16:5). Therefore it seems that an oath is not binding.

Objection 2. Further, virtue is not contrary to virtue (Categ. viii, 22). Now an oath is an act of virtue, as stated above (Article 4). But it would sometimes be contrary to virtue, or an obstacle thereto, if one were to fulfil what one has sworn to do: for instance, if one were to swear to commit a sin, or to desist from some virtuous action. Therefore an oath is not always binding.

Objection 3. Further, sometimes a man is compelled against his will to promise something under oath. Now, "such a person is loosed by the Roman Pontiffs from the bond of his oath" (Extra, De Jurejur., cap. Verum in ea quaest., etc.). Therefore an oath is not always binding.

Objection 4. Further, no person can be under two opposite obligations. Yet sometimes the person who swears and the person to whom he swears have opposite intentions. Therefore an oath cannot always be binding.

On the contrary, It is written (Matthew 5:33): "Thou shalt perform thy oaths to the Lord."

I answer that, An obligation implies something to be done or omitted; so that apparently it regards neither the declaratory oath (which is about something present or past), nor such oaths as are about something to be effected by some other cause (as, for example, if one were to swear that it would rain tomorrow), but only such as are about things to be done by the person who swears.

Now just as a declaratory oath, which is about the future or the present, should contain the truth, so too ought the oath which is about something to be done by us in the future. Yet there is a difference: since, in the oath that is about the past or present, this obligation affects, not the thing that already has been or is, but the action of the swearer, in the point of his swearing to what is or was already true; whereas, on the contrary, in the oath that is made about something to be done by us, the obligation falls on the thing guaranteed by oath. For a man is bound to make true what he has sworn, else his oath lacks truth.

Now if this thing be such as not to be in his power, his oath is lacking in judgment of discretion: unless perchance what was possible when he swore become impossible to him through some mishap. as when a man swore to pay a sum of money, which is subsequently taken from him by force or theft. For then he would seem to be excused from fulfilling his oath, although he is bound to do what he can, as, in fact, we have already stated with regard to the obligation of a vow (88, 3, ad 2). If, on the other hand, it be something that he can do, but ought not to, either because it is essentially evil, or because it is a hindrance to a good, then his oath is lacking in justice: wherefore an oath must not be kept when it involves a sin or a hindrance to good. For in either case "its result is evil" [Cf. Bede, Homil. xix, in Decoll. S. Joan. Bapt.]

Accordingly we must conclude that whoever swears to do something is bound to do what he can for the fulfilment of truth; provided always that the other two accompanying conditions be present, namely, judgment and justice.

Reply to Objection 1. It is not the same with a simple assertion, and with an oath wherein God is called to witness: because it suffices for the truth of an assertion, that a person say what he proposes to do, since it is already true in its cause, namely, the purpose of the doer. But an oath should not be employed, save in a matter about which one is firmly certain: and, consequently, if a man employ an oath, he is bound, as far as he can, to make true what he has sworn, through reverence of the Divine witness invoked, unless it leads to an evil result, as stated.

Reply to Objection 2. An oath may lead to an evil result in two ways. First, because from the very outset it has an evil result, either through being evil of its very nature (as, if a man were to swear to commit adultery), or through being a hindrance to a greater good, as if a man were to swear not to enter religion, or not to become a cleric, or that he would not accept a prelacy, supposing it would be expedient for him to accept, or in similar cases. For oaths of this kind are unlawful from the outset: yet with a difference: because if a man swear to commit a sin, he sinned in swearing, and sins in keeping his oath: whereas if a man swear not to perform a greater good, which he is not bound to do withal, he sins indeed in swearing (through placing an obstacle to the Holy Ghost, Who is the inspirer of good purposes), yet he does not sin in keeping his oath, though he does much better if he does not keep it.

Secondly, an oath leads to an evil result through some new and unforeseen emergency. An instance is the oath of Herod, who swore to the damsel, who danced before him, that he would give her what she would ask of him. For this oath could be lawful from the outset, supposing it to have the requisite conditions, namely, that the damsel asked what it was right to grant. but the fulfilment of the oath was unlawful. Hence Ambrose says (De Officiis i, 50): "Sometimes it is wrong to fulfil a promise, and to keep an oath; as Herod, who granted the slaying of John, rather than refuse what he had promised."

Reply to Objection 3. There is a twofold obligation in the oath which a man takes under compulsion: one, whereby he is beholden to the person to whom he promises something; and this obligation is cancelled by the compulsion, because he that used force deserves that the promise made to him should not be kept. The other is an obligation whereby a man is beholden to God, in virtue of which he is bound to fulfil what he has promised in His name. This obligation is not removed in the tribunal of conscience, because that man ought rather to suffer temporal loss, than violate his oath. He can, however, seek in a court of justice to recover what he has paid, or denounce the matter to his superior even if he has sworn to the contrary, because such an oath would lead to evil results since it would be contrary to public justice. The Roman Pontiffs, in absolving men from oaths of this kind, did not pronounce such oaths to be unbinding, but relaxed the obligation for some just cause.

Reply to Objection 4. When the intention of the swearer is not the same as the intention of the person to whom he swears, if this be due to the swearer's guile, he must keep his oath in accordance with the sound understanding of the person to whom the oath is made. Hence Isidore says (De Summo Bono ii, 31): "However artful a man may be in wording his oath, God Who witnesses his conscience accepts his oath as understood by the person to whom it is made." And that this refers to the deceitful oath is clear from what follows: "He is doubly guilty who both takes God's name in vain, and tricks his neighbor by guile." If, however, the swearer uses no guile, he is bound in accordance with his own intention. Wherefore Gregory says (Moral. xxvi, 7): "The human ear takes such like words in their natural outward sense, but the Divine judgment interprets them according to our inward intention."

Article 8. Whether an oath is more binding than a vow?

Objection 1. It would seem that an oath is more binding than a vow. A vow is a simple promise: whereas an oath includes, besides a promise, an appeal to God as witness. Therefore an oath is more binding than a vow.

Objection 2. Further, the weaker is wont to be confirmed by the stronger. Now a vow is sometimes confirmed by an oath. Therefore an oath is stronger than a vow.

Objection 3. Further, the obligation of a vow arises from the deliberation of the mind, a stated above (Question 88, Article 1); while the obligation of an oath results from the truth of God Whose testimony is invoked. Since therefore God's truth is something greater than human deliberation, it seems that the obligation of an oath is greater than that of a vow.

On the contrary, A vow binds one to God while an oath sometimes binds one to man. Now one is more bound to God than to man. Therefore a vow is more binding than an oath.

I answer that, The obligation both of vow and of an oath arises from something Divine; but in different ways. For the obligation of a vow arises from the fidelity we owe God, which binds us to fulfil our promises to Him. On the other hand, the obligation of an oath arises from the reverence we owe Him which binds us to make true what we promise in His name. Now every act of infidelity includes an irreverence, but not conversely, because the infidelity of a subject to his lord would seem to be the greatest irreverence. Hence a vow by its very nature is more binding than an oath.

Reply to Objection 1. A vow is not any kind of promise, but a promise made to God; and to be unfaithful to God is most grievous.

Reply to Objection 2. An oath is added to a vow not because it is more stable, but because greater stability results from "two immutable things" [Hebrews 6:18.

Reply to Objection 3. Deliberation of the mind gives a vow its stability, on the part of the person who takes the vow: but it has a greater cause of stability on the part of God, to Whom the vow is offered.

Article 9. Whether anyone can dispense from an oath?

Objection 1. It would seem that no one can dispense from an oath. Just as truth is required for a declaratory oath, which is about the past or the present, so too is it required for a promissory oath, which is about the future. Now no one can dispense a man from swearing to the truth about present or past things. Therefore neither can anyone dispense a man from making truth that which he has promised by oath to do in the future.

Objection 2. Further, a promissory oath is used for the benefit of the person to whom the promise is made. But, apparently, he cannot release the other from his oath, since it would be contrary to the reverence of God. Much less therefore can a dispensation from this oath be granted by anyone.

Objection 3. Further, any bishop can grant a dispensation from a vow, except certain vows reserved to the Pope alone, as stated above (88, 12, ad 3). Therefore in like manner, if an oath admits of dispensation, any bishop can dispense from an oath. And yet seemingly this is to be against the law [Caus. XV, qu. 6, can. Auctoritatem, seqq.: Cap. Si vero, de Jurejurando]. Therefore it would seem that an oath does not admit of dispensation.

On the contrary, A vow is more binding than an oath, as stated above (Article 8). But a vow admits of dispensation and therefore an oath does also.

I answer that, As stated above (Question 88, Article 10), the necessity of a dispensation both from the law and from a vow arises from the fact that something which is useful and morally good in itself and considered in general, may be morally evil and hurtful in respect of some particular emergency: and such a case comes under neither law nor vow. Now anything morally evil or hurtful is incompatible with the matter of an oath: for if it be morally evil it is opposed to justice, and if it be hurtful it is contrary to judgment. Therefore an oath likewise admits of dispensation.

Reply to Objection 1. A dispensation from an oath does not imply a permission to do anything against the oath: for this is impossible, since the keeping of an oath comes under a Divine precept, which does not admit of dispensation: but it implies that what hitherto came under an oath no longer comes under it, as not being due matter for an oath, just as we have said with regard to vows (88, 10, ad 2). Now the matter of a declaratory oath, which is about something past or present, has already acquired a certain necessity, and has become unchangeable, wherefore the dispensation will regard not the matter but the act itself of the oath: so that such a dispensation would be directly contrary to the Divine precept. On the other hand, the matter of a promissory oath is something future, which admits of change, so that, to wit, in certain emergencies, it may be unlawful or hurtful, and consequently undue matter for an oath. Therefore a promissory oath admits of dispensation, since such dispensation regards the matter of an oath, and is not contrary to the Divine precept about the keeping of oaths.

Reply to Objection 2. One man may promise something under oath to another in two ways. First, when he promises something for his benefit: for instance, if he promise to serve him, or to give him money: and from such a promise he can be released by the person to whom he made it: for he is understood to have already kept his promise to him when he acts towards him according to his will. Secondly, one man promises another something pertaining to God's honor or to the benefit of others: for instance, if a man promise another under oath that he will enter religion, or perform some act of kindness. On this case the person to whom the promise is made cannot release him that made the promise, because it was made principally not to him but to God: unless perchance it included some condition, for instance, "provided he give his consent" or some such like condition.

Reply to Objection 3. Sometimes that which is made the matter of a promissory oath is manifestly opposed to justice, either because it is a sin, as when a man swears to commit a murder, or because it is an obstacle to a greater good, as when a man swears not to enter a religion: and such an oath requires no dispensation. But in the former case a man is bound not to keep such an oath, while in the latter it is lawful for him to keep or not to keep the oath, as stated above (07, ad 2). Sometimes what is promised on oath is doubtfully right or wrong, useful or harmful, either in itself or under the circumstance. On this case any bishop can dispense. Sometimes, however, that which is promised under oath is manifestly lawful and beneficial. An oath of this kind seemingly admits not of dispensation but of commutation, when there occurs something better to be done for the common good, in which case the matter would seem to belong chiefly to the power of the Pope, who has charge over the whole Church; and even of absolute relaxation, for this too belongs in general to the Pope in all matters regarding the administration of things ecclesiastical. Thus it is competent to any man to cancel an oath made by one of his subjects in matters that come under his authority: for instance, a father may annul his daughter's oath, and a husband his wife's (Numbers 30:6, seqq.), as stated above with regard to vows (88, A8,9).

Article 10. Whether an oath is voided by a condition of person or time?

Objection 1. It would seem that an oath is not voided by a condition of person or time. An oath, according to the Apostle (Hebrews 6:16), is employed for the purpose of confirmation. Now it is competent to anyone to confirm his assertion, and at any time. Therefore it would seem that an oath is not voided by a condition of person or time.

Objection 2. Further, to swear by God is more than to swear by the Gospels: wherefore Chrysostom [Hom. xliv in the Opus Imperfectum falsely ascribed to St. John Chrysostom] says: "If there is a reason for swearing, it seems a small thing to swear by God, but a great thing to swear by the Gospels. To those who think thus, it must be said: Nonsense! the Scriptures were made for God's sake, not God for the sake of the Scriptures." Now men of all conditions and at all times are wont to swear by God. Much more, therefore, is it lawful to swear by the Gospels.

Objection 3. Further, the same effect does not proceed from contrary causes, since contrary causes produce contrary effects. Now some are debarred from swearing on account of some personal defect; children, for instance, before the age of fourteen, and persons who have already committed perjury. Therefore it would seem that a person ought not to be debarred from swearing either on account of his dignity, as clerics, or on account of the solemnity of the time.

Objection 4. Further, in this world no living man is equal in dignity to an angel: for it is written (Matthew 11:11) that "he that is the lesser in the kingdom of heaven is greater than he," namely than John the Baptist, while yet living. Now an angel is competent to swear, for it is written (Apocalypse 10:6) that the angel "swore by Him that liveth for ever and ever." Therefore no man ought to be excused from swearing, on account of his dignity.

On the contrary, It is stated (II, qu. v, can. Si quis presbyter): "Let a priest be examined 'by his sacred consecration,' instead of being put on his oath": and (22, qu. v, can. Nullus): "Let no one in ecclesiastical orders dare to swear on the Holy Gospels to a layman."

I answer that, Two things are to be considered in an oath. One is on the part of God, whose testimony is invoked, and in this respect we should hold an oath in the greatest reverence. For this reason children before the age of puberty are debarred from taking oaths [Caus. XXII, qu. 5, can. Parvuli], and are not called upon to swear, because they have not yet attained the perfect use of reason, so as to be able to take a oath with due reverence. Perjurers also are debarred from taking an oath, because it is presumed from their antecedents that they will not treat an oath with the reverence due to it. For this same reason, in order that oaths might be treated with due reverence the law says (22, qu. v, can. Honestum): "It is becoming that he who ventures to swear on holy things should do so fasting, with all propriety and fear of God."

The other thing to be considered is on the part of the man, whose assertion is confirmed by oath. For a man's assertion needs no confirmation save because there is a doubt about it. Now it derogates from a person's dignity that one should doubt about the truth of what he says, wherefore "it becomes not persons of great dignity to swear." For this reason the law says (II, qu. v, can. Si quis presbyter) that "priests should not swear for trifling reasons." Nevertheless it is lawful for them to swear if there be need for it, or if great good may result therefrom. Especially is this the case in spiritual affairs, when moreover it is becoming that they should take oath on days of solemnity, since they ought then to devote themselves to spiritual matters. Nor should they on such occasions take oaths temporal matters, except perhaps in cases grave necessity.

Reply to Objection 1. Some are unable to confirm their own assertions on account of their own defect: and some there are whose words should be so certain that they need no confirmation.

Reply to Objection 2. The greater the thing sworn by, the holier and the more binding is the oath, considered in itself, as Augustine states (Ad Public., Ep. xlvii): and accordingly is a graver matter to swear by God than the Gospels. Yet the contrary may be the case on account of the manner of swearing for instance, an oath by the Gospels might be taken with deliberation and solemnity, and an oath by God frivolously and without deliberation.

Reply to Objection 3. Nothing prevents the same thing from arising out of contrary causes, by way of superabundance and defect. It is in this way that some are debarred from swearing, through being of so great authority that it is unbecoming for them to swear; while others are of such little authority that their oaths have no standing.

Reply to Objection 4. The angel's oath is adduced not on account of any defect in the angel, as though one ought not to credit his mere word, but in order to show that the statement made issues from God's infallible disposition. Thus too God is sometimes spoken of by Scripture as swearing, in order to express the immutability of His word, as the Apostle declares (Hebrews 6:17).

Question 90. The taking of God's name by way of adjuration

Article 1. Whether it is lawful to adjure a man?

Objection 1. It would seem that it is not lawful to adjure a man. Origen says (Tract. xxxv super Matth.): "I deem that a man who wishes to live according to the Gospel should not adjure another man. For if, according to the Gospel mandate of Christ, it be unlawful to swear, it is evident that neither is it lawful to adjure: and consequently it is manifest that the high-priest unlawfully adjured Jesus by the living God."

Objection 2. Further, whoever adjures a man, compels him after a fashion. But it is unlawful to compel a man against his will. Therefore seemingly it is also unlawful to adjure a man.

Objection 3. Further, to adjure is to induce a person to swear. Now it belongs to man's superior to induce him to swear, for the superior imposes an oath on his subject. Therefore subjects cannot adjure their superiors.

On the contrary, Even when we pray God we implore Him by certain holy things: and the Apostle too besought the faithful "by the mercy of God" (Romans 12:1): and this seems to be a kind of adjuration. Therefore it is lawful to adjure.

I answer that, A man who utters a promissory oath, swearing by his reverence for the Divine name, which he invokes in confirmation of his promise, binds himself to do what he has undertaken, and so orders himself unchangeably to do a certain thing. Now just as a man can order himself to do a certain thing, so too can he order others, by beseeching his superiors, or by commanding his inferiors, as stated above (Question 83, Article 1). Accordingly when either of these orderings is confirmed by something Divine it is an adjuration. Yet there is this difference between them, that man is master of his own actions but not of those of others; wherefore he can put himself under an obligation by invoking the Divine name, whereas he cannot put others under such an obligation unless they be his subjects, whom he can compel on the strength of the oath they have taken.

Therefore, if a man by invoking the name of God, or any holy thing, intends by this adjuration to put one who is not his subject under an obligation to do a certain thing, in the same way as he would bind himself by oath, such an adjuration is unlawful, because he usurps over another a power which he has not. But superiors may bind their inferiors by this kind of adjuration, if there be need for it.

If, however, he merely intend, through reverence of the Divine name or of some holy thing, to obtain something from the other man without putting him under any obligation, such an adjuration may be lawfully employed in respect of anyone.

Reply to Objection 1. Origen is speaking of an adjuration whereby a man intends to put another under an obligation, in the same way as he would bind himself by oath: for thus did the high-priest presume to adjure our Lord Jesus Christ [Matthew 26:63].

Reply to Objection 2. This argument considers the adjuration which imposes an obligation.

Reply to Objection 3. To adjure is not to induce a man to swear, but to employ terms resembling an oath in order to provoke another to do a certain thing.

Moreover, we adjure God in one way and man in another; because when we adjure a man we intend to alter his will by appealing to his reverence for a holy thing: and we cannot have such an intention in respect of God Whose will is immutable. If we obtain something from God through His eternal will, it is due, not to our merits, but to His goodness.

Article 2. Whether it is lawful to adjure the demons?

Objection 1. It would seem unlawful to adjure the demons. Origen says (Tract. xxxv, super Matth.): "To adjure the demons is not accordance with the power given by our Saviour: for this is a Jewish practice." Now rather than imitate the rites of the Jews, we should use the power given by Christ. Therefore it is not lawful to adjure the demons.

Objection 2. Further, many make use of necromantic incantations when invoking the demons by something Divine: and this is an adjuration. Therefore, if it be lawful to adjure the demons, it is lawful to make use of necromantic incantations, which is evidently false. Therefore the antecedent is false also.

Objection 3. Further, whoever adjures a person, by that very fact associates himself with him. Now it is not lawful to have fellowship with the demons, according to 1 Corinthians 10:20, "I would not that you should be made partakers with devils." Therefore it is not lawful to adjure the demons.

On the contrary, It is written (Mark 16:17): "In My name they shall cast out devils." Now to induce anyone to do a certain thing for the sake of God's name is to adjure. Therefore it is lawful to adjure the demons.

I answer that, As stated in the preceding article, there are two ways of adjuring: one by way of prayer or inducement through reverence of some holy thing: the other by way of compulsion. On the first way it is not lawful to adjure the demons because such a way seems to savor of benevolence or friendship, which it is unlawful to bear towards the demons. As to the second kind of adjuration, which is by compulsion, we may lawfully use it for some purposes, and not for others. For during the course of this life the demons are our adversaries: and their actions are not subject to our disposal but to that of God and the holy angels, because, as Augustine says (De Trin. iii, 4), "the rebel spirit is ruled by the just spirit." Accordingly we may repulse the demons, as being our enemies, by adjuring them through the power of God's name, lest they do us harm of soul or body, in accord with the Divine power given by Christ, as recorded by Luke 10:19: "Behold, I have given you power to tread upon serpents and scorpions, and upon all the power of the enemy: and nothing shall hurt you."

It is not, however, lawful to adjure them for the purpose of learning something from them, or of obtaining something through them, for this would amount to holding fellowship with them: except perhaps when certain holy men, by special instinct or Divine revelation, make use of the demons' actions in order to obtain certain results: thus we read of the Blessed James [the Greater; cf. Apocrypha, N.T., Hist. Certam. Apost. vi, 19 that he caused Hermogenes to be brought to him, by the instrumentality of the demons.

Reply to Objection 1. Origen is speaking of adjuration made, not authoritatively by way of compulsion, but rather by way of a friendly appeal.

Reply to Objection 2. Necromancers adjure and invoke the demons in order to obtain or learn something from them: and this is unlawful, as stated above. Wherefore Chrysostom, commenting on our Lord's words to the unclean spirit (Mark 1:25), "Speak no more, and go out of the man," says: "A salutary teaching is given us here, lest we believe the demons, however much they speak the truth."

Reply to Objection 3. This argument considers the adjuration whereby the demon's help is besought in doing or learning something: for this savors of fellowship with them. On the other hand, to repulse the demons by adjuring them, is to sever oneself from their fellowship.

Article 3. Whether it is lawful to adjure an irrational creature?

Objection 1. It would seem unlawful to adjure an irrational creature. An adjuration consists of spoken words. But it is useless to speak to one that understands not, such as an irrational creature. Therefore it is vain and unlawful to adjure an irrational creature.

Objection 2. Further, seemingly wherever adjuration is admissible, swearing is also admissible. But swearing is not consistent with an irrational creature. Therefore it would seem unlawful to employ adjuration towards one.

Objection 3. Further, there are two ways of adjuring, as explained above (1 and 2). One is by way of appeal; and this cannot be employed towards irrational creatures, since they are not masters of their own actions. The other kind of adjuration is by way of compulsion: and, seemingly, neither is it lawful to use this towards them, because we have not the power to command irrational creatures, but only He of Whom it was said (Matthew 8:27): "For the winds and the sea obey Him." Therefore in no way, apparently, is it lawful to adjure irrational creatures.

On the contrary, Simon and Jude are related to have adjured dragons and to have commanded them to withdraw into the desert. [From the apocryphal Historiae Certam. Apost. vi. 19.]

I answer that, Irrational creatures are directed to their own actions by some other agent. Now the action of what is directed and moved is also the action of the director and mover: thus the movement of the arrow is an operation of the archer. Wherefore the operation of the irrational creature is ascribed not only to it, but also and chiefly to God, Who disposes the movements of all things. It is also ascribed to the devil, who, by God's permission, makes use of irrational creatures in order to inflict harm on man.

Accordingly the adjuration of an irrational creature may be of two kinds. First, so that the adjuration is referred to the irrational creature in itself: and in this way it would be vain to adjure an irrational creature. Secondly, so that it be referred to the director and mover of the irrational creature, and in this sense a creature of this kind may be adjured in two ways. First, by way of appeal made to God, and this relates to those who work miracles by calling on God: secondly, by way of compulsion, which relates to the devil, who uses the irrational creature for our harm. This is the kind of adjuration used in the exorcisms of the Church, whereby the power of the demons is expelled from an irrational creature. But it is not lawful to adjure the demons by beseeching them to help us.

This suffices for the Replies to the Objections.

Question 98. Perjury

Article 1. Whether it is necessary for perjury that the statement confirmed on oath be false?

Objection 1. It would seem that it is not necessary for perjury that the statement confirmed on oath be false. As stated above (Question 89, Article 3), an oath should be accompanied by judgment and justice no less than by truth. Since therefore perjury is incurred through lack of truth, it is incurred likewise through lack of judgment, as when one swears indiscreetly, and through lack of justice, as when one swears to something unjust.

Objection 2. Further, that which confirms is more weighty than the thing confirmed thereby: thus in a syllogism the premises are more weighty than the conclusion. Now in an oath a man's statement is confirmed by calling on the name of God. Therefore perjury seems to consist in swearing by false gods rather than in a lack of truth in the human statement which is confirmed on oath.

Objection 3. Further, Augustine says (De Verb. Apost. Jacobi; Serm. clxxx): "Men swear falsely both in deceiving others and when they are deceived themselves"; and he gives three examples. The first is: "Supposing a man to swear, thinking that what he swears to is true, whereas it is false"; the second is: "Take the instance of another who knows the statement to be false, and swears to it as though it were true"; and the third is: "Take another, who thinks his statement false, and swears to its being true, while perhaps it is true," of whom he says afterwards that he is a perjurer. Therefore one may be a perjurer while swearing to the truth. Therefore falsehood is not necessary for perjury.

On the contrary, Perjury is defined "a falsehood confirmed by oath" [Hugh of St. Victor, Sum. Sent. iv, 5.

I answer that, As stated above (Question 92, Article 2), moral acts take their species from their end. Now the end of an oath is the confirmation of a human assertion. To this confirmation falsehood is opposed: since an assertion is confirmed by being firmly shown to be true; and this cannot happen to that which is false. Hence falsehood directly annuls the end of an oath: and for this reason, that perversity in swearing, which is called perjury, takes its species chiefly from falsehood. Consequently falsehood is essential to perjury.

Reply to Objection 1. As Jerome says on Jeremiah 4:2, "whichever of these three be lacking, there is perjury," but in different order. For first and chiefly perjury consists in a lack of truth, for the reason stated in the Article. Secondly, there is perjury when justice is lacking, for in whatever way a man swears to that which is unlawful, for this very reason he is guilty of falsehood, since he is under an obligation to do the contrary. Thirdly, there is perjury when judgment is lacking, since by the very fact that a man swears indiscreetly, he incurs the danger of lapsing into falsehood.

Reply to Objection 2. In syllogisms the premises are of greater weight, since they are in the position of active principle, as stated in Phys. ii, 3: whereas in moral matters the end is of greater importance than the active principle. Hence though it is a perverse oath when a man swears to the truth by false gods, yet perjury takes its name from that kind of perversity in an oath, that deprives the oath of its end, by swearing what is false.

Reply to Objection 3. Moral acts proceed from the will, whose object is the apprehended good. Wherefore if the false be apprehended as true, it will be materially false, but formally true, as related to the will. If something false be apprehended as false, it will be false both materially and formally. If that which is true be apprehended as false, it will be materially true, and formally false. Hence in each of these cases the conditions required for perjury are to be found in some way, on account of some measure of falsehood. Since, however, that which is formal in anything is of greater importance than that which is material, he that swears to a falsehood thinking it true is not so much of a perjurer as he that swears to the truth thinking it false. For Augustine says (De Verb. Apost. Jacobi; Serm. clxxx): "It depends how the assertion proceeds from the mind, for the tongue is not guilty except the mind be guilty."

Article 2. Whether all perjury is sinful?

Objection 1. It would seem that not all perjury is sinful. Whoever does not fulfil what he has confirmed on oath is seemingly a perjurer. Yet sometimes a man swears he will do something unlawful (adultery, for instance, or murder): and if he does it, he commits a sin. If therefore he would commit a sin even if he did it not, it would follow that he is perplexed.

Objection 2. Further, no man sins by doing what is best. Yet sometimes by committing a perjury one does what is best: as when a man swears not to enter religion, or not to do some kind of virtuous deed. Therefore not all perjury is sinful.

Objection 3. Further, he that swears to do another's will would seem to be guilty of perjury unless he do it. Yet it may happen sometimes that he sins not, if he do not the man's will: for instance, if the latter order him to do something too hard and unbearable. Therefore seemingly not all perjury is sinful.

Objection 4. Further, a promissory oath extends to future, just as a declaratory oath extends to past and present things. Now the obligation of an oath may be removed by some future occurrence: thus a state may swear to fulfil some obligation, and afterwards other citizens come on the scene who did not take the oath; or a canon may swear to keep the statutes of a certain church, and afterwards new statutes are made. Therefore seemingly he that breaks an oath does not sin.

On the contrary, Augustine says (De Verb. Apost. Jacobi; Serm. cxxx), in speaking of perjury: "See how you should detest this horrible beast and exterminate it from all human business."

I answer that, As stated above (Question 89, Article 1), to swear is to call God as witness. Now it is an irreverence to God to call Him to witness to a falsehood, because by so doing one implies either that God ignores the truth or that He is willing to bear witness to a falsehood. Therefore perjury is manifestly a sin opposed to religion, to which it belongs to show reverence to God.

Reply to Objection 1. He that swears to do what is unlawful is thereby guilty of perjury through lack of justice: though, if he fails to keep his oath, he is not guilty of perjury in this respect, since that which he swore to do was not a fit matter of an oath.

Reply to Objection 2. A person who swears not to enter religion, or not to give an alms, or the like, is guilty of perjury through lack of judgment. Hence when he does that which is best it is not an act of perjury, but contrary thereto: for the contrary of that which he is doing could not be a matter of an oath.

Reply to Objection 3. When one man swears or promises to do another's will, there is to be understood this requisite condition--that the thing commanded be lawful and virtuous, and not unbearable or immoderate.

Reply to Objection 4. An oath is a personal act, and so when a man becomes a citizen of a state, he is not bound, as by oath, to fulfil whatever the state has sworn to do. Yet he is bound by a kind of fidelity, the nature of which obligation is that he should take his share of the state's burdens if he takes a share of its goods.

The canon who swears to keep the statutes that have force in some particular "college" is not bound by his oath to keep any that may be made in the future, unless he intends to bind himself to keep all, past and future. Nevertheless he is bound to keep them by virtue of the statutes themselves, since they are possessed of coercive force, as stated above (I-II, 96, 4).

Article 3. Whether all perjury is a mortal sin?

Objection 1. It would seem that not all perjury is a mortal sin. It is laid down (Extra, De Jurejur, cap. Verum): "Referring to the question whether an oath is binding on those who have taken one in order to safeguard their life and possessions, we have no other mind than that which our predecessors the Roman Pontiffs are known to have had, and who absolved such persons from the obligations of their oath. Henceforth, that discretion may be observed, and in order to avoid occasions of perjury, let them not be told expressly not to keep their oath: but if they should not keep it, they are not for this reason to be punished as for a mortal sin." Therefore not all perjury is a mortal sin.

Objection 2. Further, as Chrysostom [Hom. xliv in the Opus Imperfectum on St. Matthew, falsely ascribed to St. John Chrysostom] says, "it is a greater thing to swear by God than by the Gospels." Now it is not always a mortal sin to swear by God to something false; for instance, if we were to employ such an oath in fun or by a slip of the tongue in the course of an ordinary conversation. Therefore neither is it always a mortal sin to break an oath that has been taken solemnly on the Gospels.

Objection 3. Further, according to the Law a man incurs infamy through committing perjury (VI, qu. i, cap. Onfames). Now it would seem that infamy is not incurred through any kind of perjury, as it is prescribed in the case of a declaratory oath violated by perjury [Cap. Cum dilectus, de Ord. Cognit.]. Therefore, seemingly, not all perjury is a mortal sin.

On the contrary, Every sin that is contrary to a divine precept is a mortal sin. Now perjury is contrary to a divine precept, for it is written (Leviticus 19:12): "Thou shalt not swear falsely by My name." Therefore it is a mortal sin.

I answer that, According to the teaching of the Philosopher (Poster. i, 2), "that which causes a thing to be such is yet more so." Now we know that an action which is, by reason of its very nature, a venial sin, or even a good action, is a mortal sin if it be done out of contempt of God. Wherefore any action that of its nature, implies contempt of God is a mortal sin. Now perjury, of its very nature implies contempt of God, since, as stated above (Article 2), the reason why it is sinful is because it is an act of irreverence towards God. Therefore it is manifest that perjury, of its very nature, is a mortal sin.

Reply to Objection 1. As stated above (89, 07, ad 3), coercion does not deprive a promissory oath of its binding force, as regards that which can be done lawfully. Wherefore he who fails to fulfil an oath which he took under coercion is guilty of perjury and sins mortally. Nevertheless the Sovereign Pontiff can, by his authority, absolve a man from an obligation even of an oath, especially if the latter should have been coerced into taking the oath through such fear as may overcome a high-principled man.

When, however, it is said that these persons are not to be punished as for a mortal sin, this does not mean that they are not guilty of mortal sin, but that a lesser punishment is to be inflicted on them.

Reply to Objection 2. He that swears falsely in fun is nonetheless irreverent to God, indeed, in a way, he is more so, and consequently is not excused from mortal sin. He that swears falsely by a slip of tongue, if he adverts to the fact that he is swearing, and that he is swearing to something false, is not excused from mortal sin, as neither is he excused from contempt of God. If, however, he does not advert to this, he would seem to have no intention of swearing, and consequently is excused from the sin of perjury.

It is, however, a more grievous sin to swear solemnly by the Gospels, than to swear by God in ordinary conversation, both on account of scandal and on account of the greater deliberation. But if we consider them equally in comparison with one another, it is more grievous to commit perjury in swearing by God than in swearing by the Gospels.

Reply to Objection 3. Not every sin makes a man infamous in the eye of the law. Wherefore, if a man who has sworn falsely in a declaratory oath be not infamous in the eye of the law, but only when he has been so declared by sentence in a court of law, it does not follow that he has not sinned mortally. The reason why the law attaches infamy rather to one who breaks a promissory oath taken solemnly is that he still has it in his power after he has sworn to substantiate his oath, which is not the case in a declaratory oath.

Article 4. Whether he sins who demands an oath of a perjurer?

Objection 1. It would seem that he who demands an oath of a perjurer commits a sin. Either he knows that he swears truly, or he knows that he swears falsely. If he knows him to swear truly, it is useless for him to demand an oath: and if he believes him to swear falsely, for his own part he leads him into sin. Therefore nowise seemingly should one enjoin an oath on another person.

Objection 2. Further, to receive an oath from a person is less than to impose an oath on him. Now it would seem unlawful to receive an oath from a person, especially if he swear falsely, because he would then seem to consent in his sin. Much less therefore would it seem lawful to impose an oath on one who swears falsely.

Objection 3. Further, it is written (Leviticus 5:1): "If anyone sin, and hear the voice of one swearing falsely ['Falsely' is not in the Vulgate'], and is a witness either because he himself hath seen, or is privy to it: if he do not utter it, he shall bear his iniquity." Hence it would seem that when a man knows another to be swearing falsely, he is bound to denounce him. Therefore it is not lawful to demand an oath of such a man.

Objection 4. On the other hand, Just as it is a sin to swear falsely so is it to swear by false gods. Yet it is lawful to take advantage of an oath of one who has sworn by false gods, as Augustine says (ad Public. Ep. xlvii). Therefore it is lawful to demand an oath from one who swears falsely.

I answer that, As regards a person who demands an oath from another, a distinction would seem to be necessary. For either he demands the oath on his own account and of his own accord, or he demands it on account of the exigencies of a duty imposed on him. If a man demands an oath on his own account as a private individual, we must make a distinction, as does Augustine (de Perjuriis. serm. clxxx): "For if he knows not that the man will swear falsely, and says to him accordingly: 'Swear to me' in order that he may be credited, there is no sin: yet it is a human temptation" (because, to wit, it proceeds from his weakness in doubting whether the man will speak the truth). "This is the evil whereof Our Lord says (Matthew 5:37): That which is over and above these, is of evil. But if he knows the man to have done so," i.e. the contrary of what he swears to, "and yet forces him to swear, he is a murderer: for the other destroys himself by his perjury, but it is he who urged the hand of the slayer."

If, on the other hand, a man demands an oath as a public person, in accordance with the requirements of the law, on the requisition of a third person: he does not seem to be at fault, if he demands an oath of a person, whether he knows that he will swear falsely or truly, because seemingly it is not he that exacts the oath but the person at whose instance he demands it.

Reply to Objection 1. This argument avails in the case of one who demands an oath on his own account. Yet he does not always know that the other will swear truly or falsely, for at times he has doubts about the fact, and believes he will swear truly. On such a case he exacts an oath in order that he may be more certain.

Reply to Objection 2. As Augustine says (ad Public. serm. xlvii), "though we are forbidden to swear, I do not remember ever to have read in the Holy Scriptures that we must not accept oaths from others." Hence he that accepts an oath does not sin, except perchance when of his own accord he forces another to swear, knowing that he will swear falsely.

Reply to Objection 3. As Augustine says (QQ. Super Lev, qu. i), Moses in the passage quoted did not state to whom one man had to denounce another's perjury: wherefore it must be understood that the matter had to be denounced "to those who would do the perjurer good rather than harm." Again, neither did he state in what order the denunciation was to be made: wherefore seemingly the Gospel order should be followed, if the sin of perjury should be hidden, especially when it does not tend to another person's injury: because if it did, the Gospel order would not apply to the case, as stated above (33, 07; 68, 1).

Reply to Objection 4. It is lawful to make use of an evil for the sake of good, as God does, but it is not lawful to lead anyone to do evil. Consequently it is lawful to accept the oath of one who is ready to swear by false gods, but it is not lawful to induce him to swear by false gods. Yet it seems to be different in the case of one who swears falsely by the true God, because an oath of this kind lacks the good of faith, which a man makes use of in the oath of one who swears truly by false gods, as Augustine says (ad Public. Ep. xlvii). Hence when a man swears falsely by the true God his oath seems to lack any good that one may use lawfully.