Question IV: What is required for an oath

The QUESTION concerns the requirements of the Divine natural law for the lawful manner of swearing. The constant sentiment of the Theologians is that three things are required, as it were companions, from Jeremiah 4, Thou shalt swear: The Lord liveth in truth, and in Judgment, and in justice. So St. Jerome expounds it, and it is cited caus. 22. quaest. 2. et cap. ultimo 22. quaest. 4. St. Thomas has this 2. 2. quaest. 89. art. 3. St. Bonaventure in 3. dist. 39. quaest. 1. et in dub. lit. where he observes that an Oath is compared to three things, namely to the one swearing, from whom it proceeds: to the thing, or matter of the oath, about which one swears: and to the cause for which, or through which one swears. In the one who swears (he says) judgment is required, that is, discretion, and a certain prudence necessary for every one swearing. These three things are required, says Valencia. The first is, that what we affirm with an oath cannot be sufficiently proved without the oath; for then it would be an abuse of the oath; for the institution of swearing ought to be referred to contingent and hidden facts alone, which need the proof of Divine testimony, before whose eyes all things are naked and open. The second is, that some pious cause for swearing be present. The third is, that the one about to swear diligently foresee whether what he is about to swear be true or false. But the second condition seems to be reduced to justice by St. Bonaventure. Yet I do not think it so, as I shall say below.

IN order, however, to the thing about which one swears, truth is required, at least according to the reasonable judgment of the one swearing. Yet Truth is required differently in an Assertory oath and in a Promissory one; for in a Promissory oath a twofold truth is required; one consists in the concordance of the promissory word and the interior intention of doing in its own time what is promised: the other truth is the concord also of the effect, or of the thing promised, with the promise, and this is properly the truth of a promissory oath. But the truth in an Assertory oath is the union, that is, the concord of the assertion with the deliberate mind, as I said.

IN order to the cause, through which, or about which one swears, justice is necessary, namely that the act of swearing be just, that is, not against the laws, and be done for a just cause. And indeed in a Promissory oath justice is required not only in the act; namely that it not harm one's neighbor, but also in the matter of the oath; namely that it be a just work, reducible to some virtue, even if indifferent in itself, as I shall say quaest. 13. But in an Assertory oath justice is not required on the part of the matter; for the crime of one's neighbor is often lawfully uncovered by an oath; but justice is required in the act of swearing alone, namely that it harm no one. St. Bonaventure indicates this, when he says that justice is required, that it be done for a just cause, not on account of a just cause, which pertains to the judgment of discretion; and therefore he says prudently also that justice is required in the cause about which, that is, in the matter of the oath, insofar as it formally has the character of the cause of the oath in the Promissory; and in the act, insofar as it is productive of the oath in the Assertory.

From the lack, therefore, of any of these circumstances the oath is rendered unlawful; for if justice is lacking, the one swearing makes God, as far as in him lies, a cooperator of evil, and the Oath is called iniquitous, or unjust. If truth is lacking, God is made either ignorant or wicked; for it is necessary that he who is the witness of falsehood be one or the other, and then the oath is called false, or perjury properly speaking. Finally, if judgment is lacking, irreverence is inflicted upon God, since he is dragged forth in testimony without cause, and the oath is called heedless and rash. See St. Bonaventure, especially sermone 3. in Decalogum.

From these is resolved the first question of St. Bonaventure, namely whether in every perjury there is a lie.

For there can be perjury because it was rashly uttered; yet not a lie, since the one swearing thought from inconsideration that it was true. St. Bonaventure proves this in corpore, from St. Augustine serm. 23. de verbis Apostoli. Therefore from the defect of the judgment of discretion there arises a perjury which is not formally a lie.

FURTHERMORE the defect of an oath can come from injustice, as if someone should swear to commit murder, rape, or another crime with the intention of fulfilling it; it will not be a lie, and yet it will be perjury broadly; It will nevertheless be a lie, if he swears not with the intention of fulfilling the promise. So St. Bonaventure loco cit.; for that is properly perjury which properly opposes the end of the oath, which is to establish truth. Therefore, if only justice is lacking, it will be perjury in the broad mode, as Sanchez notes cap. 8. num. 5.

The REASON, therefore, of a lie stands in the defect of Truth, if the falsehood uttered by voice is intended; but if you intend to say what is true, and say what is false from inconsideration, there will be rashness, as I said; for a lie formally ought to be directly voluntary; nevertheless a falsehood uttered also from rashness is in some way a lie, at least broadly.

From these you have that, taking a lie broadly, in every perjury, as opposed to an assertory oath, there is a lie; but if a lie be taken properly and strictly, it is not found in every promissory oath; nor in every assertory one. See Valencia quaest. 14. puncto 1. Tanner disp. 5. quaest. 8. dub. 1. Fagundez in 2. Praec. lib. 2. cap. 51. Clarum lib. 5.

The Holy Doctor CONCLUDES, therefore, from the testimony of Jeremiah and Jerome cited, that there is properly a lie from the violation of the second condition alone, that is, of Truth, but not from the violation of Judgment, or of Justice;

Of Justice; yet from each of them singly it comes about that one sins against the law of the oath, which requires those three conditions. So also in the opusc. declaratorio terminorum Theol.