Article II: On the Quality and Extension of the Obligation of Preceptive Law

344. Preceptive or moral law is that which commands some good to be done or prohibits some evil to be avoided. The observance of this law is not always an act of that species and virtue to which the matter of itself pertains, but of that virtue from whose formal motive the law has been enacted: for virtues and good human acts are distinguished by the formal object or motive. Thus fasting of itself is an act of abstinence, and the Lenten fast is such when it is prescribed from such a motive; but fasting before communion is an act of religion, which is imposed from the formal motive of religion. Whence he who transgresses a precept sins against that virtue from whose motive the precept is borne.

From these things it follows that the transgression of a precept is a sin of formal disobedience only if it is borne from the special motive of obedience, but not in other cases, unless the transgression is made from contempt. No ecclesiastical law seems to have been enacted from the special motive of obedience.

345. Preceptive law founded on a presumption of right is that which rests on a reasonable conjecture or probability taken from circumstances often connected with truth. For presumption is a probable conjecture concerning an uncertain matter (can. 1825, § 1): thus, e.g., a law obligating one to the sentence of a judge, which is presumed just, to the execution of a contract which is supposed to have been validly entered upon unless the contrary is proved; likewise a law by which a child is judged to have the use of reason from the seventh year (c. 88, § 3), and a pubescent person is judged to know what marriage is (c. 1082, § 2).

1. One is of right only if contrary and direct proof is admitted in the external forum, e.g., c. 1015, § 2; another is of right concerning right, when the judge is forbidden to attend to contrary and direct proof, e.g., for a thing adjudged (c. 1904, § 1). Nevertheless indirect proof is admitted against the very fact upon which the presumption is founded (c. 1826).

One is founded on a presumption of a particular fact when the superior presumes that a fact, e.g., damage, fraud, consent, negligence, exists not in common and for the most part, but in any particular case, and therefore makes a law for all similar cases: thus in the examples given. Another is founded on a presumption of common danger when he presumes that from such a work or mode of acting, for the most part, ordinarily and commonly there follows damage, fraud, scandal, etc., and therefore he prohibits it, e.g., to read depraved books: it does not suppose fraud or scandal or damage, but the danger of them.

The first per se does not obligate if the presumption in the particular case is false, because then the foundation of the law is lacking, which is the presumption of this particular fact; hence you are not bound to pay money for damage falsely presumed.

Whence the saying: the same judgment is made in the forum of conscience and in the forum of the court is true in cases in which the external forum does not rest on a false presumption of a particular fact. Per accidens, however, in the external forum we are bound to obey, by reason of public order and scandal; but then we can compensate ourselves secretly (even after the sentence of the judge). But we cannot obey if the matter is illicit, as if someone were to seek or render the debt in a marriage certainly invalid which is presumed valid in the external forum.

The second per se always obligates, even in particular cases in which damage or its danger does not intervene, because the foundation of the law remains.

a) For the superior did not make the law because he presumes damage in any given case, but because he presumes that for men commonly it is so; therefore, as long as the common danger remains, so long the law itself remains.

b) Moreover, the common good demands that no exception be admitted; otherwise the evils to be avoided would not be impeded efficaciously, because each person would easily persuade himself that there is no danger with regard to himself. The law intends to forestall this false persuasion, and also to render men more diligent for avoiding harms. Thus ecclesiastical law enacted to forestall a general danger of perversion or spiritual detriment, just as civil law is enacted to forestall a general danger of negligence.

c) In other words: a law does not cease unless the end ceases adequately, that is, totally and as to all. But in the case, even if danger does not exist for the individual, it perseveres for the community. Therefore the law does not cease. For its end is to avoid common danger; now common danger cannot efficaciously and certainly be avoided if the law did not urge absolutely and for all, since each person would easily persuade himself that the danger is not present for himself, from which the end of the law would be frustrated.

Hence, just as civil law, to forestall the general danger of negligence, obligates one guilty of merely juridic fault to repair damage, e.g., to pay for damage caused by a dog without moral fault, by which law the judgment of danger is withdrawn from subjects; so also ecclesiastical law obligates when it prohibits religious profession before sixteen years, invalidates clandestine marriage, prohibits mixed marriages or books entered in the Index, even if it is clear that no fraud, or defect of liberty, or damage is present. This doctrine is now confirmed by can. 21.

346. A law founded on a fiction of right is not to be confused with a law founded on presumption.

1. No law, properly speaking, is founded on fiction, since fiction is nothing. But the reason of the common good, e.g., equity, moves that the same thing be established as for a true case.

For presumption is a reasonable conjecture in an uncertain matter, but a fiction of right is a disposition by which the legislator, from a just cause, establishes the same thing for a fictive case as another law establishes in a true case, e.g., that canons absent from choir because of infirmity are held as present with regard to daily distributions (can. 420), or that a marriage by which antecedent offspring is legitimated is judged valid from the time of this conception or birth (can. 1117), or that offspring born in a marriage which afterward is proved null is judged legitimate (can. 1114), or that an invalid marriage, if it is sanated in the root, is judged valid from the beginning (can. 1138).

Therefore presumption rests on verisimilitude, fiction on equity; presumption is assumed in a doubtful case according to verisimilitude, fiction in a certain case against the truth.

Such a law, if it is just, obligates in conscience.

Nevertheless, note that 1) fiction has place only in cases expressed in law;

2. fiction ought not to operate more in the fictive case than truth operates in the true case;

3. it is not valid beyond that which is expressed in the law: thus for the deceased and the heir there is held to be unity of person with regard to inheritance, not with regard to other things;

4. finally, it is to be interpreted strictly.

347. Permitting law is not the absence of law, nor mere license or simple toleration, but a true law which positively acknowledges in man liberty, either internal or at least external, or juridic capacity, for doing something. Such a law obligates others not to impede the aforesaid acts, and judges not to punish them. Likewise a law concessive of rights obligates others not to deprive one of them or impede one from legitimate action. Nevertheless it is not a merely prohibitive law for others, but bestows a special right, grants a faculty or capacity.