Chapter V — What an oath is; various formulas of swearing are explained

I. An oath is defined by St. Thomas (II-II, q. 89, art. 1) as being "an invocation of the divine name to make faith, or to confirm a promise." St. Augustine, cited by St. Thomas himself in the place cited, defines the oath in these words (Sermon 28, On the Words of the Apostle): "What is it to swear by God, but that God is witness?" It differs from prayer, since by the latter divine aid is sought; by the former, however, it is asked that the truth be manifested. Wherefore Franz Buddeus, the Lutheran, wretchedly errs, who, in his Moral Theology Institutions, Vol. II, ch. 3, §5, n. 10, blurts out that God is not here regarded as witness, as though an oath were a testimony of God, or as though God himself testified concerning the truth of the swearer. This error of that Lutheran collapses of itself, says the same Angelic Doctor, as though pertaining to a "right"; for an oath is called "introduced from right" — that is, in order that what is asserted under the invocation of divine testimony may be held as true. For there are certain deeds, either hidden, or contingent, which cannot be proved by human testimony; and therefore it has been established, and decreed, by law, that they be confirmed by divine testimony, necessity compelling it, and that faith be given to facts confirmed by divine testimony.

II. Iuramentum, iusiurandum, and sacramentum are synonyms. From Scripture it is established that iuramentum and iusiurandum are used for the same thing, according to that of Luke 1: "The oath, which he swore to Abraham our father, that he would grant to us." It is also called sacramentum, both in Scripture and in law, as is established from the chapter "Qui sacramentum," 22, q. 4. And although the word sacramentum has other, more proper significations, it is nonetheless also used for an oath — since this too is a sign of a sacred thing, namely, of infallible truth.

III. For a clearer understanding of the given definition, St. Thomas, in the place cited, in his reply to the first objection, notes that we can use divine testimony in two ways. First, by that testimony which God has already given in his Scriptures — namely, when we allege that very text, or authority, of Scripture to prove some truth: while we do this, we swear in no way. Second, when we implore his testimony to be given — namely, that God may manifest the truth of that fact in confirmation of which we invoke his testimony. And in this manner we swear. Moreover, when we invoke God as witness in this way, so that he may confirm our assertions, we do not intend that God should immediately, by some evident prodigy or miracle, confirm our assertions by his own authority, and manifest them — for whoever did this would tempt God; but we ask only that God add his testimony to our words, and reveal the truth, whenever it shall please him, in life or in death, in this age or in the future one.

IV. Divine testimony can be invoked in two ways. First, expressly, when God himself is brought forward as witness; second, tacitly, when the testimony of creatures is invoked with a peculiar respect to God — which we shall explain more clearly below. In both ways, however, one swears, since in both ways divine testimony is implored.

V. This invocation of divine testimony can be made by word, as if you utter aloud, "I swear by God"; by nod, as if, to one asking whether you swear by God, you nod your assent with your eyes, or head, or by some gesture; by touch, as if, when an oath is offered to you upon a book of the Gospels, and you touch the book itself, even if you utter nothing, you are reckoned to swear; by mind, as if within your own soul you swear that you will do something, you bind yourself, by the virtue of religion, to carry it out in the internal forum; but in order to be obliged in the external forum, it is necessary that the oath uttered be manifested externally by one of the three signs described.

VI. If someone swore, touching the Book of the Gospels, and afterward discovered that this book was entirely a profane one, it would nonetheless be a true oath, and he ought to observe it — because there would be only a material diversity, since the swearer intended to swear by the sacred Gospel, whichever it was. On the contrary, one who swears by false gods does not make an oath at all — since only the true God deserves to have faith paid to him by men.

VII. Since the words by which an oath is uttered are not fixed, it follows that there are very many formulas of oaths. We can reduce all of them to a threefold kind. Of the first kind are those which, according to common sense and understanding, contain an oath, or an invocation of divine testimony; and these are held, in every forum, to be oaths, unless it clearly appears that the one uttering them had a contrary intention. Of the second kind are those which, in common understanding, do not contain the assumption of divine testimony; and these are not held to be an oath, unless one who utters them declares that he wished, by those words, to elicit an oath. Of the third kind, finally, are those which are ambiguous, and which sometimes contain an oath, sometimes not, according to the various manner in which they are uttered. The matter will appear clearer by examples.

VIII. Of the first kind are: "I swear by God," "God is my witness," "God lives," "I invoke the living God as witness." Nor, however, is it necessary that the word "witness" be used; but it suffices to confirm one's own assertions by "by God," "by the faith of God," "by the faith of Christ." To this class too may be reduced oaths made by creatures, as when one says, "by heaven," "by the earth," "by my soul," "by my health," "by the Angels," "by the Blessed Virgin," "by the Saints," etc. Here, however, I would have you note that the testimony of creatures can be invoked in several ways. First, as an infallible argument of truth — and this invocation would be blasphemous, since God alone is infallible. Second, rational creatures can be invoked, as persons endowed with a certain peculiar authority, so that they may lend credence to our words, without respect to God — and this invocation does not constitute an oath, just as we do not swear when we call living men as witnesses. Third, creatures are called to witness the truth, insofar as the divine majesty especially shines forth in them, and they have a peculiar relation to God, and their invocation singularly excites in us the memory of God — as when we swear by the Gospels, by temples, by altars, by heaven, by the earth, by the elements. It must be judged otherwise, when one swears by the lowest and vilest creatures — as if someone swore by his own beard, by his own hair, by his own dog, etc. — this would not be a true oath. For although all these are creatures of God, in them, according to common understanding, the divine majesty does not shine forth in any peculiar manner. If, however, someone, invoking these creatures, at the same time named God obliquely, it would be an oath — as if someone said, "By this bread of God," "by the fire of God," "by the air of God," "by this stone of God," "by this creature of God." For whenever God, whether in the direct or the oblique case, is called to witness, an oath is uttered. To this class are likewise reduced the Italian formulas "Se Dio m'aiuti" ["so help me God"], and similar ones: "So may God help me," "may the demon seize me," "may I die," "may I perish, if it is not so." These oaths are execratory, and yield this sense: "I offer myself to death, may the demon deliver me over," etc.

IX. "May God not help me, if it is not true"; "God help me not, if it is not so." To the second class are reduced the following formulas: "In truth," "in the truth of the matter," "I profess," "by my faith," "on my faith," "on the faith of a good man," "by the faith of an honest man," "by my honor," "on my conscience." Such formulas, according to common estimation, do not have the force of an oath. Unless, then, one who utters them has the express intention of swearing, they are not oaths. If, however, someone, uttering the aforesaid words, intended to call God to witness, they would be oaths. Authors commonly, whom I follow, likewise assert that these are not oaths: "by the faith of a good Christian," "on the faith of a Christian," "on the faith of a Religious," "by the faith of the Priesthood" — commonly, "Da Cristiano," "alla fè di Cristiano," "da Religioso," "da Sacerdote," "in fede di Sacerdote." For, they say, in these expressions, divine faith is not invoked, but human faith; and they hold this sense: "I speak as a good Christian, a good Priest, ought to speak." So the theologians of Salamanca (tract. 17, ch. 2, punct. 3, n. 23).

Authors, and indeed the common view among Casuists in practice, must be candidly admitted here. But, since I do not have a reason available to me by which I could free the aforesaid formulas from the force of an oath, I judge that such expressions should in no way be permitted to Christians in common speech. Theologians commonly assert that to swear by sacred things, say, by temples, by altars, by the relics of the Saints, is a true oath. Why, then, will it not be an oath to say, "by the faith of a Christian," "of a Religious," or of a "Priest"? Is not the priesthood sacred, is not the religious state sacred, is not the Christian condition, or Christianity, sacred, and the priestly profession? If someone should say, "by this habit," or "this garment, of St. Peter, of St. Francis, of St. Dominic," all authors, and consequently the cited ones too, hold that he truly swears. Why, then, will he not swear, if he says, "on the habit," or "by the faith of a Priest"?

I fear, then, that these authors interpret the aforesaid formulas so as not to hold that an oath is contained in them, because men everywhere use it; and, lest they should condemn very many as guilty of perjury, they teach that they do not truly swear at all. Nor indeed does it rarely happen that horror is withdrawn from vices, when men cannot be withdrawn from vices. I do not deny that oaths depend greatly on the intention of the swearer. But when locutions betray the force of an oath, even though the lack either of intention or of consideration may excuse, or diminish, the past malice, a Confessor is not excused, however, from obliging penitents to guard their tongue, nor a penitent, if he does not strive to abstain from the aforesaid formulas. It should be added that men commonly take such expressions — "by the faith of a Priest," "of a Religious," commonly "da Sacerdote," "da Religioso" — as an oath.

Nevertheless, what we have said concerning these three last formulas — namely, "by the faith of a Christian, of a Religious, of a Priest" — is not so manifest to us that we should condemn the contrary and common opinion. For only moral certainty sometimes compels us to depart from the common opinion of more recent authors. This certainty being lacking, we too accede to the common opinion. And because we confess that such certainty is not now present to us on this matter, we therefore proclaim the contrary opinion probable. In practice, however, I would bid all whose confessions I might hear to abstain from such expressions. Sotus, too (Bk. VIII, on justice and law, art. 5, q. 1, concl. 3), speaks doubtfully of these manners of swearing.

X. The following formulas — "I vow to God," "I swear to God," "I promise to God"; commonly, "voto a Dio," "giuro a Dio," "prometto a Dio" — contain a true oath, since God is really called to witness. And although such expressions may seem to have the character of a vow and of a promise, nonetheless, since those who utter them employ them in confirmation of their assertions, they constitute an oath. The following formula, however — "I swear that I will do this," or "that this is so," with no word added — is, by the force of the words themselves, and by its own nature, an oath. The theologians of Salamanca teach the contrary (tract. 17, ch. 2, punct. 3, n. 34), Bonacina (disp. 4, punct. 1, near the end). The theologians of Salamanca, and Bonacina too, allege Suárez in their favor, but falsely; indeed, he teaches the opposite, saying (Bk. IV, ch. 13, n. 4): "'By oneself,' and by force of the word, in its rigorous signification, without doubt suffices for swearing. In use, however, the circumstances must be considered." We too teach the same thing. The aforesaid words absolutely betray an oath; the intention, however, of the one uttering them, and other circumstances, must be attended to. Wherefore, if something is added which withdraws those words from the invocation of divine testimony, it will not be an oath — as, for instance, if someone were to swear in this manner, "I swear by my beard," "I swear by ten," "I swear by myself" — none of these would be an oath. Authors commonly hold, too, that no oath at all is present in these formulas, if one who says, "I swear by this cross," designates no cross — since one who abstains from forming the sign of the cross is presumed to have had no intention of swearing. But if he formed a cross, he would utter an oath. The circumstances, however, must be observed. Similarly, if someone, asked to affirm something under oath, responded, "I swear that it is so," he would truly swear.

XI. To the third class are reduced the formulas which sometimes contain an oath, and sometimes do not — of which kind are: "God knows," "I speak in the sight of God," "God sees that it is so." These, if uttered enunciatively, are not oaths; on the contrary, they are just as much oaths, if pronounced invocatively — as is established from the Apostle Paul, swearing to the Galatians (ch. 1) in these words: "Now the things which I write to you, behold, before God, I lie not." I would have you note, however, that, to discern whether they are uttered enunciatively or invocatively, not only the intention of the one speaking, but also the manner of speaking, must be examined. For if it is said, "God hears what I speak," "God sees what I do," unless the contrary intention is established, an oath is not presumed. On the contrary, however, if it is said, "God knows that I speak the truth," Navarrus, in his Manual, ch. 12, n. 2, Leander, tract. 1, disp. 12, q. 4, maintain that such a formula contains a true oath — an opinion which indeed seems to me probable enough. For the rest, since the aforesaid formula includes some ambiguity, the circumstances are therefore to be attended to, and especially the intention of the speaker.

XII. Several authors also reduce to this class the following formulas: "God is my witness that I speak the truth," "God lives," "the Lord lives," "God is truth." But the more common opinion, and the one that alone seems true to me, teaches the opposite. Since, to begin with the first formula, St. Thomas (II-II, q. 89, art. 1, ad 3) absolutely asserts that it contains an oath. St. Augustine teaches the same (Sermon 28, on the words of the Apostle, ch. 6): "Not without reason do those who, wishing to distinguish oaths, I know not how, or rather not understanding, say that it is not an oath, when a man says, 'God knows,' 'God is witness,' 'God sees.' He invoked God: he made God his witness. What else do they wish, but, God being invoked as witness, to lie? Are you not swearing, of a perverse heart, if you say, 'By God'? Are you not swearing, if you say, 'God is witness'? For what is it to swear, but to render right to God? Whoever you are, of a wicked heart, do you render right to God, when you swear falsely by him? For what is 'by God,' but 'God is witness'? Or what is 'God is witness,' but 'I invoke God upon my soul, that I speak the truth' — does he not swear? Those who say these things do so only when you swear by God; to render right to your health, when you swear by your health; to render right to your children, when you swear by your children. But what right do we owe to our health, to our children, to our God, except of charity, of truth, not of falsehood? But it is chiefly by God that the true oath is made, since, when one says, 'by my health,' he binds his health over to God; when he says, 'by my children,' he pledges his children to God, so that it may come upon their head, that which comes forth from his own mouth: if true, it is true; if false, it is false." Wherefore Sporer, Felix Potestas, La Croix, and many other Casuists wrongly place that formula among the ambiguous formulas of swearing. Of the other formulas the matter is clearer, since Scripture uses them as a true oath. Jeremiah 4: "They will swear: 'The Lord liveth.'" Elijah used the same formula (3 Kings 17): "As the Lord liveth, the God of Israel, in whose sight I stand." In no way, then, are the aforesaid formulas to be reckoned among equivocal expressions, whatever many recent writers assert.

XIII. The following sayings do not contain an oath: "May I be wicked," "a liar," "faithless," "a heretic," "may I perish," "may my nose, or ears, be cut off, if it is not so." For such locutions, according to common understanding, contain only a certain... wish, not an oath. The following formulas, however — "May I be slain," "may I die," "may I perish" — if uttered by way of execration, contain an oath, as has been said above. For they yield this sense: "May God, whom I call to witness, kill me, if what I assert is not true." It must be judged otherwise, if they are pronounced only enunciatively — for commonly, in this manner, they do not render more than a certain pledge. It likewise seems to me not probable that "I swear by myself," "by him who I am"; commonly, "giuro da quel che sono," is an oath. For although man is, according to the common view, a singular creature of God, nonetheless, according to the common opinion, nothing else is understood by this than an interposition of human faith and authority.