Article IV: Concerning Incest

I. Incest (bloedschande, bloedschennis) is copulation between blood relatives or those related by affinity. It is prohibited by natural law indeterminately for blood relatives; hence how far and to what degree the prohibition extends must be determined by positive law. For the non-baptized it is determined by civil law or custom; for the baptized, by ecclesiastical law. Thus incest is between those who, according to the law of the Church, cannot enter a valid marriage, or concubitus with a blood relative or one related by affinity within the degrees prohibited by the Church for marriage. The prohibited degrees in consanguinity extend to the third inclusive for the collateral line; in affinity, which now arises from marriage even ratified, to the second; in each, to any degree whatever for the direct line (can. 1076 and 1077). But if in some degree a legitimate dispensation has been obtained, it is no longer incest.

It is called incest (in-castus): as if by antonomasia it were against chastity.

II. Incest is a distinct species of lust because it contains a twofold grave malice, against chastity and against piety, or the reverence owed to relatives. Lev. XVIII, 6 and following; XX, 11, 12, 14; Deut. XXII, 20, 22, 23; I Cor. V, 1-5. Saint Thomas shows this thus, II-II, q. 154, art. 9:

"There it is necessary to find a determinate species of lust where there is found something repugnant to the due use of venereal things. But in the use of blood relatives or those related by affinity there is found something unfitting to venereal mingling for a threefold reason:

"First, because naturally man owes a certain honor to parents, and consequently to other blood relatives who draw their origin from the same parents in near degree.... But it is manifest ... that in venereal acts there especially consists a certain baseness contrary to honor; whence men are ashamed concerning these things. And therefore it is unfitting that such venereal mingling be done between such persons with one another....

"The second reason is that persons joined by blood necessarily live together. Hence, if men were not kept away from venereal mingling, too much opportunity would be given to men for venereal mingling ... especially because, as Aristotle says, Politics II, c. 2, since man naturally loves a blood relative, if there were added the love which is from venereal mingling, there would be too great an ardor and the greatest incentive of libido, which is repugnant to chastity.

"The third reason is that by this the multiplication of friends would be impeded. When a man takes an outside wife, all the blood relatives of the wife are joined to him by a certain special friendship, as if they were his own blood relatives."

III. Incests among blood relatives do not differ in species from those which are had among those related by affinity, because "a person related by affinity is joined to someone because of the blood-related person joined to him; and therefore, because one is for the sake of the other, consanguinity and affinity make an unfittingness of the same notion, not degree" (ibid., ad 2). Indeed, according to many, all incests are of the same lowest species; but others say that incest among blood relatives of the direct line is distinguished in species from all others, or even incest between brothers and sisters.¹

¹ Which the faithful easily judge.

Sometimes, however, another office of piety can be violated at the same time, and then certainly a diverse species is present: thus, for example, the incest of parents with children constituted under their power, because they detract from the office of right instruction; likewise, as it seems, the incest of a son with a stepmother while the father is living, by reason of the great injury toward the parent.

IV. Just as there is carnal kinship from the bond of blood, so there can be legal kinship from perfect adoption, which nevertheless is not recognized in Belgian law, and spiritual kinship arising from baptism between the one baptizing and the sponsors on one side, and the baptized on the other (can. 768). Such kinship differs in species from carnal kinship; and therefore besides incest properly so called, there can exist legal incest diverse in species, and there does exist spiritual incest, if copulation is had between the one baptizing or the sponsor and the baptized. This last includes malice against religion, because it is against the reverence of the sacrament.

V. Observation. Carnal sin committed by a bishop or pastor or rector of a college, and so forth, with subjects, although it is not spiritual incest properly so called because per se no spiritual kinship is present, nevertheless includes a malice of injustice diverse in species, insofar as someone induces to sin those whom by office he ought to draw back from vice. The mere cooperators of a pastor or moderator of a college do not necessarily sin in this way, although they can sin by scandal. Nor does the confessor who, outside confession, sins carnally with a penitent, because he neither contracts spiritual kinship nor acts as a spiritual superior, but as an equal, not in confession but outside it. But if he solicited on the occasion of confession, it would be carnal sacrilege.

VI. Warning. Sometimes it happens that the sinner does not perceive the special malice of incest in copulation had with more remote blood relatives or with those related by affinity. In such a case, so that he may conceive a greater horror of the sin, he will generally have to be instructed.