Affinity (designated in Heb. by some form of the verb חָת - ן, chathan', to give in marriage) is relationship by marriage, as distinguished from consanguinity, which is relationship by blood.
1. Marriages between persons thus related, in various degrees, which previous usage, in different conditions of society, had allowed, were forbidden by the law of Moses. These degrees are enumerated in Le 18:7 sq. The examples before the law are those of Cain and Abel, who, as the necessity of the case required, married their own sisters.
Abraham married Sarah, the daughter of his father by another wife; and Jacob married the two sisters Leah and Rachel. In the first instance, and even in the second, there was an obvious consanguinity, and only the last offered a previous relationship of affinity merely. So also, in the prohibition of the law, a consanguinity can be traced in what are usually set down as degrees of affinity merely. The degrees of real affinity interdicted are. that a man shall not (nor a woman in the corresponding relations) marry,
(1), his father's widow (not his own mother);
(2), the daughter of his father's wife by another husband;
(3), the widow of his paternal uncle;
(4), nor his brother's widow if he has left children by her; but, if not, he was bound to marry her to raise up children to his deceased brother. SEE LEVIRATE LAW.
The other restrictions are connected with the condition of polygamy, and they prohibit a man from having,
(1), a mother and her daughter for wives at the same time,
(2), or two sisters for wives at the same time.
These prohibitions, although founded in Oriental notions, adapted to a particular condition of society, and connected with the peculiarities of the Levitical marriage law, have been imported wholesale into our canon law. The fitness of this is doubted by many; but as, apart from any moral or sanitary questions, the prohibited marriages are such as few would, in the present condition of Occidental society, desire to contract, and such as would be deemed repugnant to good taste and correct manners, there is little real matter of regret in this adoption of the Levitical law. Indeed the objections have arisen chiefly from a misunderstanding of the last of the above prohibitions, which, under permitted polygamy, forbade a man to have two sisters at once — an injunction which has been construed under the Christian law, which allows but one wife, to apply equally to the case of a man marrying the sister of a deceased wife. The law itself is rendered in our version, "Neither shalt thou take a wife to her sister, to vex her, to uncover her nakedness, beside the other in her lifetime" (Le 18:18). Clear as this seems, it is still clearer if, with Gesenius and others, we take the word צָרִר, tsarar', rendered to vex, to mean to rival, as in the Septuagint, Arabic, and Vulgate. The Targum of Jonathan, the Mishna, and the celebrated Jewish commentators Jarchi and Ben Gerson, are satisfied that two sisters at once are intended; and there seems an obvious design to prevent the occurrence of such unseemly jealousies and contentions between sister-wives as embittered the life of the patriarch Jacob. The more recondite sense has been extracted, with rather ungentle violence to the principles of Hebrew construction, by making "vex her" the antecedent of "in her lifetime," instead of "take her sister to her, in her lifetime." Under this view it is explained that the married sister should not be "vexed" in her lifetime by the prospect that her sister might succeed her. It may be safely said that such an idea would never have occurred in the East, where unmarried sisters are far more rarely than in Europe brought into such acquaintance with the husband of the married sister as to give occasion for such "vexation" or "rivalry" as this. Yet this view of the matter, which is completely exploded among sound Biblical critics, has received the sanction of several Christian councils (Concil. Illiber. can. 61; Aurat. can. 17; Auxer. can. 30), and is perhaps not calculated to do much harm, except under peculiar circumstances, and except as it may prove a snare to some sincere but weak consciences. It may be remarked that, in those codes of law which most resemble that of Moses on the general subject, no prohibition of the marriage of two sisters in succession can be found. (See Westhead, Marriage Code of Israel, Lond. 1850; Critici Sac. Thes. Nov. 1, 379.) SEE MARRIAGE.
2. The substance of the Levitical law is adopted in England, and may be found in the "table of degrees" within which persons may not marry, which was set forth by Archbishop Parker in 1563, and was confirmed by can. 99 of the synod of London, 1604. SEE INCEST.
3. According to the Roman canon law, affinity arises from marriage or from an unlawful intercourse between the one party and the blood relations of the other party; but in either case it is necessary that copula sit completa (S. Thomas, 4to, dist. 41, qu. 1, art. 1). Persons related to each other may contract affinity, as the husband with the relations of his wife, without the relations of the parties becoming bound together by any affinity; e.g. two brothers may marry two sisters, a father and his son may marry a mother and her daughter. The impediment of affinity, arising from marriage consummated, extends canonically, as in natural relationship, to the fourth degree inclusive. The impediment of affinity arising ex coitu illicito only extends to the second degree (Conc. Trid. sess. 24, de reform. cap. 4). It is ruled in the Latin Church that the pope cannot dispense in the first degree of affinity in the direct line, but he can in the indirect; thus he can grant a dispensation to a man to marry his brother's widow. SEE CONSANGUINITY.