Article I: On the Quantity or Gravity of Obligation

St. Thomas, II-II, q. 105, a. 2.

341. The gravity of obligation in ecclesiastical law depends on two things: on the gravity of the matter and on the will of the legislator, who at least must have an implicit intention of obligating under grave sin. Whence:

a) if the matter is light in every respect, even considering the end and circumstances, the law cannot obligate under grave sin: for such matter is not capable of grave obligation, nor can the legislator make it that light matter, which conducts little and lightly influences the end or common good, should conduct much and gravely influence it, or that small disobedience should be great; moreover such a law is not conformable to reason, nor would it tend to the common good, but rather would be an occasion of ruin;

b) if the matter is grave and the legislator intends to obligate under light sin, the obligation is only light: for by distinction from natural law, in which both obligation and its gravity necessarily and immediately arise from the very gravity and necessity of the matter, the proximate and immediate cause of obligation in positive law is the will of the legislator; therefore the obligation is as great as the legislator wills, and just as it depends upon him that the law exist and obligate, so also that it be grave or light. And although by acting thus the legislator sometimes can sin, nevertheless the obligation, because it is the effect of his own will, does not extend beyond that which he willed.

342. The gravity of matter is weighed by reason of the end and of aptitude for this end:

A. Matter is indeed grave when it is an efficacious means to a great good, namely, when the special or proximate end is of great moment as to the common good, very useful, morally necessary, and at the same time that which is prescribed by the law conduces much to obtaining the end. Such is the dignity of sacred worship, the service of God, penance, the sanctity of the clergy, etc., to which the use of sacred vestments, the observance of feasts, abstinence from meat, celibacy, contribute much. Whence a thing light in itself can be grave matter, as was the eating of the forbidden fruit in paradise by reason of the acknowledgment of God and the subjection of man to God: so, e.g., entering a house by reason of scandal or danger, the mingling of water and wine by reason of the representation of a great mystery in the sacrifice.

B. On the contrary, if the special end is not of great moment, or if it is of great moment and the action does not conduct much to the end, the matter is light; thus the order among the diverse hours of the breviary does not contribute much to the glorification of God.

343. Practical rules for discerning grave or light obligation.

A. Positive law obligates under grave sin when the matter is grave, that is, when it conduces much to an end of great moment, and at the same time the legislator wills to command under grave sin.

a) if he uses gravely threatening or more severe words, e.g., if he commands in virtue of holy Obedience, under the indignation of God, under threat of divine judgment, etc.;

b) if he imposes a grave penalty, e.g., of death, mutilation, perpetual prison, exile, deposition, privation of goods, censure, irregularity, reservation, privation of ecclesiastical burial (can. 2218, § 2): for a penalty, in order to be just, must be proportioned to the delict;

c) if in grave matter he uses ordinary words: we mandate, we command, we prohibit, etc., and does not express that he wills to obligate under light sin, nor is this gathered from the circumstances, especially, e.g., from the excessive burden which the law would impose, he is judged to obligate under grave sin: for he is presumed to act reasonably and ordinarily to obligate according to the capacity and exigency of the matter. Nor must he explicitly intend grave obligation: just as he must not explicitly intend obligation in conscience, but make a law, and thus he implicitly wills obligation, in the same way by commanding grave matter, he is judged implicitly to will to command under grave sin;

d) if the custom and usage of the faithful and the practice of the God-fearing interpret the law thus;

e) if the prudent, pious, and learned unanimously judge thus.

C. But if there is doubt about these things, the law is judged to obligate under light sin, unless the legislator urges it under grave sin, because then the presumption stands for him.