Objection 1: It would seem that affinity in itself admits of degrees. For any kind of propinquity can itself be the subject of degrees. Now affinity is a kind of propinquity. Therefore it has degrees in itself apart from the degrees of consanguinity by which it is caused.
Objection 2: Further, it is stated in the text (Sent. iv, D, 41) that the child of a second marriage could not take a consort from within the degrees of affinity of the first husband. But this would not be the case unless the son of an affine were also affine. Therefore affinity like consanguinity admits itself of degrees.
On the contrary, Affinity is caused by consanguinity. Therefore all the degrees of affinity are caused by the degrees of consanguinity: and so it has no degrees of itself.
I answer that, A thing does not of itself admit of being divided except in reference to something belonging to it by reason of its genus: thus animal is divided into rational and irrational and not into white and black. Now carnal procreation has a direct relation to consanguinity, because the tie of consanguinity is immediately contracted through it; whereas it has no relation to affinity except through consanguinity which is the latter's cause. Wherefore since the degrees of relationship are distinguished in reference to carnal procreation, the distinction of degrees is directly and immediately referable to consanguinity, and to affinity through consanguinity. Hence the general rule in seeking the degrees of affinity is that in whatever degree of consanguinity I am related to the husband, in that same degree of affinity I am related to the wife.
Reply to Objection 1: The degrees in propinquity of relationship can only be taken in reference to ascent and descent of propagation, to which affinity is compared only through consanguinity. Wherefore affinity has no direct degrees, but derives them according to the degrees of consanguinity.
Reply to Objection 2: Formerly it used to be said that the son of my affine by a second marriage was affine to me, not directly but accidentally as it were: wherefore he was forbidden to marry on account of the justice of public honesty rather than affinity. And for this reason this prohibition is now revoked.
Whether the degrees of affinity extend in the same way as the degrees of consanguinity?
Objection 1: It would seem that the degrees of affinity do not extend in the same way as the degrees of consanguinity. For the tie of affinity is less strong than the tie of consanguinity, since affinity arises from consanguinity in diversity of species, as from an equivocal cause. Now the stronger the tie the longer it lasts. Therefore the tie of affinity does not last to the same number of degrees as consanguinity.
Objection 2: Further, human law should imitate Divine law. Now according to the Divine law certain degrees of consanguinity were forbidden, in which degrees affinity was not an impediment to marriage: as instanced in a brother's wife whom a man could marry although he could not marry her sister. Therefore now too the prohibition of affinity and consanguinity should not extend to the same degrees.
On the contrary, A woman is connected with me by affinity from the very fact that she is married to a blood-relation of mine. Therefore in whatever degree her husband is related to me by blood she is related to me in that same degree by affinity: and so the degrees of affinity should be reckoned in the same number as the degrees of consanguinity.
I answer that, Since the degrees of affinity are reckoned according to the degrees of consanguinity, the degrees of affinity must needs be the same in number as those of consanguinity. Nevertheless, affinity being a lesser tie than consanguinity, both formerly and now, a dispensation is more easily granted in the more remote degrees of affinity than in the remote degrees of consanguinity.
Reply to Objection 1: The fact that the tie of affinity is less than the tie of consanguinity causes a difference in the kind of relationship but not in the degrees. Hence this argument is not to the point.
Reply to Objection 2: A man could not take his deceased brother's wife except, in the case when the latter died without issue, in order to raise up seed to his brother. This was requisite at a time when religious worship was propagated by means of the propagation of the flesh, which is not the case now. Hence it is clear that he did not marry her in his own person as it were, but as supplying the place of his brother.
Whether a marriage contracted by persons with the degrees of affinity or consanguinity should always be annulled?
Objection 1: It would seem that a marriage contracted by persons within the degrees of affinity or consanguinity ought not always to be annulled by divorce. For "what God hath joined together let no man put asunder" ( Mat. 19:6 ). Since then it is understood that what the Church does God does, and since the Church sometimes through ignorance joins such persons together, it would seem that if subsequently this came to knowledge they ought not to be separated.
Objection 2: Further, the tie of marriage is less onerous than the tie of ownership. Now after a long time a man may acquire by prescription the ownership of a thing of which he was not the owner. Therefore by length of time a marriage becomes good in law, although it was not so before.
Objection 3: Further, of like things we judge alike. Now if a marriage ought to be annulled on account of consanguinity, in the case when two brothers marry two sisters, if one be separated on account of consanguinity, the other ought to be separated for the same reason. and yet this is not seemly. Therefore a marriage ought not to be annulled on account of affinity or consanguinity.
On the contrary, Consanguinity and affinity forbid the contracting of a marriage and void the contract. Therefore if affinity or consanguinity be proved, the parties should be separated even though they have actually contracted marriage.
I answer that, Since all copulation apart from lawful marriage is a mortal sin, which the Church uses all her endeavors to prevent, it belongs to her to separate those between whom there cannot be valid marriage, especially those related by blood or by affinity, who cannot without incest be united in the flesh.
Reply to Objection 1: Although the Church is upheld by God's gift and authority, yet in so far as she is an assembly of men there results in her acts something of human frailty which is not Divine. Therefore a union effected in the presence of the Church who is ignorant of an impediment is not indissoluble by Divine authority, but is brought about contrary to Divine authority through man's error, which being an error of fact excuses from sin, as long as it remains. Hence when the impediment comes to the knowledge of the Church, she ought to sever the aforesaid union.
Reply to Objection 2: That which cannot be done without sin is not ratified by any prescription, for as Innocent III says (Conc. Later. iv, can. 50: cap. Non debent, De consang. et affinit.), "length of time does not diminish sin but increases it": nor can it in any way legitimize a marriage which could not take place between unlawful persons.
Reply to Objection 3: In contentious suits between two persons the verdict does not prejudice a third party, wherefore although the one brother's marriage with the one sister is annulled on account of consanguinity, the Church does not therefore annul the other marriage against which no action is taken. Yet in the tribunal of the conscience the other brother ought not on this account always to be bound to put away his wife, because such accusations frequently proceed from ill-will, and are proved by false witnesses. Hence he is not bound to form his conscience on what has been done about the other marriage: but seemingly one ought to draw a distinction, because either he has certain knowledge of the impediment of his marriage, or he has an opinion about it, or he has neither. In the first case, he can neither seek nor pay the debt, in the second, he must pay, but not ask, in the third he can both pay and ask.
Whether it is necessary to proceed by way of accusation for the annulment of a marriage contracted by persons related to each other by affinity or consanguinity?
Objection 1: It would seem that one ought not to proceed by way of accusation in order to sever a marriage contracted between persons related by affinity or consanguinity. Because accusation is preceded by inscription* whereby a man binds himself to suffer the punishment of retaliation, if he fail to prove his accusation. [*The accuser was bound by Roman Law to endorse (se inscribere) the writ of accusation; Cf. SS, Q[33], A[7]]. But this is not required when a matrimonial separation is at issue. Therefore accusation has no place then.
Objection 2: Further, in a matrimonial lawsuit only the relatives are heard, as stated in the text (Sent. iv, D, 41). But in accusations even strangers are heard. Therefore in a suit for matrimonial separation the process is not by way of accusation.