Thomas Aquinas, Summa Theologiae

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 Cor. 1:15, seqq.) though he went not to Corinth, as he had said he would (1 Cor. 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 (Mt. 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 (Question 88, Article 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"

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."

Articulus 7

Argumentum 1

Ad septimum sic proceditur. Videtur quod iuramentum non habeat vim obligandi. Inducitur enim iuramentum ad confirmandum veritatem eius quod dicitur. Sed quando aliquis dicit aliquid de futuro, verum dicit etiam si non eveniat quod dicit, sicut Paulus, quamvis non iverit Corinthum, sicut dixerat, non tamen est mentitus, ut patet II Cor. I.

Ergo videtur quod iuramentum non sit obligatorium.

Argumentum 2

Praeterea, virtus non est virtuti contraria, ut dicitur in praedicamentis.

Sed iuramentum est actus virtutis, ut dictum est.

Quandoque autem esset contra virtutem, aut in aliquod eius impedimentum, si quis servaret id quod iuravit, sicut cum aliquis iurat se facere aliquod peccatum, vel cum iurat desistere ab aliquo opere virtutis.

Ergo iuramentum non semper est obligatorium.

Argumentum 3

Praeterea, quandoque aliquis invitus compellitur ad hoc quod sub iuramento aliquid promittat. Sed tales a iuramenti nexibus sunt per Romanos pontifices absoluti, ut habetur extra, de iureiurando, cap. Verum in ea quaestione etc..

Ergo iuramentum non semper est obligatorium.

Argumentum 4

Praeterea, nullus potest obligari ad duo opposita. Sed quandoque oppositum est quod intendit iurans, et quod intendit ille cui iuramentum praestatur. Ergo iuramentum non potest semper esse obligatorium.

Sed Contra

Sed contra est quod dicitur Matth. V, reddes domino iuramenta tua.

Corpus

Respondeo dicendum quod obligatio refertur ad aliquid quod est faciendum vel dimittendum. Unde non videtur respicere iuramentum assertorium, quod est de praesenti vel de praeterito; neque etiam iuramentum de his quae sunt per alias causas fienda, sicut si quis iuramento assereret quod cras pluvia esset futura; sed solum in his quae sunt fienda per illum qui iurat. Sicut autem iuramentum assertorium, quod est de praeterito vel de praesenti, debet habere veritatem, ita etiam et iuramentum de his quae sunt fienda a nobis in futurum. Et ideo utrumque iuramentum habet quandam obligationem, diversimode tamen.

Quia in iuramento quod est de praeterito vel praesenti, obligatio est non respectu rei quae iam fuit vel est, sed respectu ipsius actus iurandi, ut scilicet iuret id quod iam verum est vel fuit.

Sed in iuramento quod praestatur de his quae sunt fienda a nobis, obligatio cadit e converso super rem quam aliquis iuramento firmavit. Tenetur enim aliquis ut faciat verum esse id quod iuravit, alioquin deest veritas iuramento. Si autem est talis res quae in eius potestate non fuit, deest iuramento discretionis iudicium, nisi forte quod erat ei possibile quando iuravit, ei reddatur impossibile per aliquem eventum; puta cum aliquis iuravit se pecuniam soluturum, quae ei postmodum VI vel furto subtrahitur. Tunc enim videtur excusatus esse a faciendo quod iuravit, licet teneatur facere quod in se est, sicut etiam supra circa obligationem voti diximus.

Si vero sit quidem possibile fieri, sed fieri non debeat, vel quia est per se malum, vel quia est boni impeditivum, tunc iuramento deest iustitia. Et ideo iuramentum non est servandum in eo casu quo est peccatum vel boni impeditivum, secundum enim utrumque horum vergit in deteriorem exitum. Sic ergo dicendum est quod quicumque iurat aliquid se facturum, obligatur ad id faciendum, ad hoc quod veritas impleatur, si tamen alii duo comites adsint, scilicet iudicium et iustitia.

Ad 1

Ad primum ergo dicendum quod aliud est de simplici verbo, aliud de iuramento, in quo divinum testimonium imploratur.

Sufficit enim ad veritatem verbi quod aliquis dicat id quod proponit se facturum, quia hoc iam verum est in sua causa, scilicet in proposito facientis. Sed iuramentum adhiberi non debet nisi in re de qua aliquis firmiter certus est. Et ideo si iuramentum adhibeatur, propter reverentiam divini testimonii quod invocatur, obligatur homo ut faciat esse verum id quod iuravit, secundum suam possibilitatem, nisi in deteriorem exitum vergat, ut dictum est.

Ad 2

Ad secundum dicendum quod iuramentum potest vergere in deteriorem exitum dupliciter. Uno modo, quia ab ipso principio habet peiorem exitum. Vel quia est secundum se malum, sicut cum aliquis iurat se adulterium patraturum. Sive quia est maioris boni impeditivum, puta cum aliquis iurat se non intraturum religionem, vel quod non fiet clericus, aut quod non accipiet praelationem in casu in quo expedit eum accipere, vel si quid aliud est huiusmodi. Huiusmodi enim iuramentum a principio est illicitum, differenter tamen.

Quia si quis iuret se facturum aliquod peccatum, et peccat iurando, et peccat iuramentum servando. Si quis autem iurat se non facturum aliquod melius bonum, quod tamen facere non tenetur, peccat quidem iurando, inquantum ponit obicem spiritui sancto, qui est boni propositi inspirator, non tamen peccat iuramentum servando, sed multo melius facit si non servet. Alio modo vergit in deteriorem exitum propter aliquid quod de novo emerserat, quod fuit impraemeditatum, sicut patet in iuramento Herodis, qui iuravit puellae saltanti se daturum quod petisset. Hoc enim iuramentum poterat esse a principio licitum, intellecta debita conditione, scilicet si peteret quod dare deceret, sed impletio iuramenti fuit illicita.

Unde Ambrosius dicit, in I de officiis, est contra officium nonnunquam promissum solvere sacramentum, sicut Herodes, qui necem ioannis praestavit ne promissum negaret.

Ad 3

Ad tertium dicendum quod in iuramento quod quis coactus facit, duplex est obligatio. Una quidem qua obligatur homini cui aliquid promittit. Et talis obligatio tollitur per coactionem, quia ille qui vim intulit hoc meretur, ut ei promissum non servetur.

Alia autem est obligatio qua quis deo obligatur ut impleat quod per nomen eius promisit. Et talis obligatio non tollitur in foro conscientiae, quia magis debet damnum temporale sustinere quam iuramentum violare. Potest tamen repetere in iudicio quod solvit, vel praelato denuntiare, non obstante si contrarium iuravit, quia tale iuramentum vergeret in deteriorem exitum, esset enim contra iustitiam publicam. Romani autem pontifices ab huiusmodi iuramentis homines absolverunt non quasi decernentes huiusmodi iuramenta non esse obligatoria, sed quasi huiusmodi obligationes ex iusta causa relaxantes.

Ad 4

Ad quartum dicendum quod quando non est eadem iurantis intentio et eius cui iurat, si hoc provenit ex dolo iurantis, debet iuramentum servari secundum sanum intellectum eius cui iuramentum praestatur.

Unde Isidorus dicit, quacumque arte verborum quis iuret, deus tamen, qui conscientiae testis est, ita hoc accipit sicut ille cui iuratur intelligit.

Et quod hoc intelligatur de doloso iuramento, patet per id quod subditur, dupliciter reus fit qui et nomen dei in vanum assumit, et proximum dolo capit.

Si autem iurans dolum non adhibeat, obligatur secundum intentionem iurantis.

Unde Gregorius dicit, XXVI Moral., humanae aures talia verba nostra iudicant qualia foris sonant, divina vero iudicia talia foris audiunt qualia ex intimis proferuntur.