Chapter III. Oaths

AN oath is the calling on God to witness to the truth of what we say. This calling on God may be express or tacit; it is express when God is mentioned, as, ‘‘ I swear by God ”’; it is tacit when we swear by some creature which in a special way shows forth the Divinity or has some special relation to him, as, ‘‘ I swear by the Christian Faith,” “‘ by the Gospel,” “by Heaven.”

In an assertory oath we call God to witness to the truth of a present or past event; in a promissory oath we call him to witness to some future event.

A solemn oath is clothed with the ceremonies prescribed by law, such as holding up the right hand or kissing the Bible; a simple oath is devoid of such ceremonies.

An imprecation is sometimes added to an oath by such words as, ‘‘ so help me God ”’; in this case we have an imprecatory oath; otherwise it is an invocatory oath.

There cannot be an oath strictly so called unless there be the intention of swearing and a suitable form of words be used which express that intention. One who uses the colloquialism, “‘ I swear it is so,’ usually has no intention of taking an oath, nor do the words signify an intention of calling on God to witness to the truth of what is said. The same must be said of phrases like ‘‘ on my honour,” “ by my faith,” * God knows ”’; and a fortiori the mention of fabulous gods, as, “‘ by Jupiter,’ etc. However, if there be an intention to take an oath, this will be sufficient to make it binding in conscience whatever the form of words may be, so that perjury will be committed if what is asserted is not true. If the form of words is suitable for an oath, the intention to swear is presumed.

If the requisite conditions be fulfilled, oaths are lawful, and indeed they are an act of divine worship, for they are an acknowledgement of the omniscience and veracity of God, as well as a public profession of belief in him. This has been the constant teaching of the Church, teaching which has ample warrant in both the Old and New Testament, The prophet 1$7 Jeremias lays down the conditions which justify an oath, and many instances of oaths are found in the epistles of the Apostle of the Gentiles. The words of our Lord¹ do not prohibit the taking of oaths if the requisite conditions be present. They give expression to his desire that all Christians should be so truthful and sincere that it will not be necessary for them to use oaths to confirm the truth of what they assert. The conditions which make an oath lawful are given in the words of Jeremias:² ‘‘ And thou shalt swear, As the Lord liveth, in truth, and in judgement, and in justice.”

We swear in truth when we are morally certain that what we assert under oath is according to fact. We are not justified in asserting that to be true which we do not know to be true and we commit the grave sin of perjury if we swear to what we know to be false.

We swear with judgement when there is a just cause for invoking the testimony of God and it is done with proper consideration and reverence. A just cause will be any matter of some importance for the welfare of either soul or body, whether it be public or private. We are not, therefore, justified in swearing to every assertion which we believe to be true; there must be some special reason for employing the name and authority of God to confirm what we say. However, provided that the other conditions are not wanting, the defect of judgement in swearing will not be more than a venial sin, for it is no more than the idle use of the name of God.

It is an insult to God to invoke his testimony to a sinful act or in furtherance of what is sinful. If this is done, the oath is unlawful on account of the want of justice. Justice, then, in this connection requires that the assertion in an assertory oath should not be sinful, such as a sin of detraction or boasting about past sins. In a promissory oath, that which is promised must be honest and lawful.

There is some difficulty and dispute among theologians about the gravity of the sin which is committed when an oath wants justice. If in an assertory oath the testimony of God is unjustifiably invoked to promote a seriously sinful object, the want of justice in the oath will be gravely sinful. If, on the contrary, the testimony of God does not further the end in view, the want of justice will probably be only venially sinful, because the assertion is true, as is here presumed, and the irreverence committed against God by invoking his testimony even to a gravely sinful act does not seem to many to be more than a venial sin.

An oath, therefore, taken to confirm detraction in a grave matter is mortally sinful; an oath confirming a boast about grave sins committed in the past is probably only venial.

Somewhat similarly in a promissory oath, if the act promised be gravely sinful, the defect of justice makes the oath gravely sinful; for it is a great insult to God to use his testimony to further what is mortally sinful. If the act promised is only a venial sin, a probable opinion holds that the oath is only venially sinful, against a more probable contrary view.

¹ Matt. v 34.

² Jer. iv 2.

The effect of a promissory oath is to bind the person swearing to do what he promises by an additional obligation derived from the virtue of religion, which requires that out of reverence for God we should religiously perform what we promised under oath. If we fail to do this in a matter of moment, grave sin will be committed, as all acknowledge. Moreover, as is obvious, if when the oath is taken there is no intention of keeping it, a grave sin of perjury is committed, for perjury is never venial on account of triviality of matter. If, however, when the oath was taken there was a serious intention of keeping it, but afterwards there was a failure to do so in a matter of small moment, a probable opinion holds that such a want of fidelity in a small matter cannot be more than a venial sin.

The obligation imposed by a promissory oath is of strict interpretation, and follows the nature of the act or contract to which it is annexed, so that it is dependent on all the conditions and limitations with which law, or custom, or the circumstances invest the act or contract. For a promissory oath is accessory and follows the nature of the principal act to which it is annexed. And so an oath to observe the rules or statutes of a corporation is understood to refer only to those that are in force.¹

¹ Can. 1318, 1321.

An oath should conduce to the service and honour of God; it cannot be a bond of iniquity; and so an oath to do what is wrong is sinful and of no effect. Similarly, an oath to do what is useless, or which hinders greater good, is null and void. In case, however, another party has acquired rights under an oath, justice requires that this should be kept, and so the mission oath, by which a sworn promise is given to serve a particular church or mission, binds a missionary priest even though he is persuaded that he has a vocation to the religious state.

In accordance with rules of canon law, an oath extorted by violence or grave fear is valid, but it can be dispensed by an ecclesiastical superior. Moreover, an oath taken without violence or fraud by which one renounces a private advantage or favour granted him by law must be kept as long as it can be kept without sin (Can. 1317, sec. 2, 3).

An oath may cease to bind from intrinsic or from extrinsic causes. If circumstances produce a change in the matter of the oath so that it has become unlawful, or useless, or an obstacle to greater good, or if some condition is not fulfilled, the oath no longer binds. The same must be said when the motive of a promissory oath no longer exists, as if I swore to help a poor person with money who subsequently becomes rich (Can. 1319).

An oath may be annulled, dispensed, commuted, or relaxed, in much the same way as a vow, and it will be more convenient to treat of these extrinsic causes for being released from the obligation of an oath in the next chapter, where the doctrine is applicable to vows and oaths alike (Can. 1320).