CHAPTER II: ON OATH

365. • Definition. An oath is an invocation of the divine Name in testimony of truth.

Division. An oath is distinguished:

1° Assertory, by which present or past things are affirmed or denied, or promissory, which extends itself only to future things. Although not every oath concerning the future is promissory. For a twofold oath concerning the future is distinguished by Doctors: one bare and simple, which contains no promise toward another, for example if you swear that you will not enter this house or tavern, etc.; but another is promissory, which is confirmatory of a promise either toward God, which is a sworn vow, or toward one's neighbor, which adds to the obligation of justice or fidelity arising from the promise an obligation from the virtue of religion.

2° Solemn, or simple, according as it is done in the form required by law, or with solemn ceremonies, or with these excluded.

3° Explicit, or implicit, according as God is expressly invoked as witness, or creatures are employed as testimony in which the divine attributes especially shine forth.

4° Contestatory, or execratory or imprecatory, according as God is invoked as witness alone, or as witness and at the same time avenger of perjury.

Yet according to the common opinion all oaths are of the same species.¹

An oath clothed with due conditions is honorable and licit, and, if it is promissory, obligates in conscience, unless a just cause stands in the way, or its obligation has legitimately ceased. - Thus all;² and it is established both from the definition of the Council of Constance, session 8, against Wycliffe (p. IX), and from the universal practice of the Church and of peoples, and also from various places of Sacred Scripture. Thou shalt fear the Lord thy God... and shalt swear by His name.³

The obligation of swearing presses as often as an oath is either necessary for helping one's neighbor, or is legitimately exacted by a Superior.