Plurality of Wives

The natural law is, as we have said many times, the eternal law of God for right human conduct, inasmuch as this law can be known by sound reason without divine revelation. It may be called man’s natural awareness of what is right and fitting. Whatever upsets the normal proportion of an action or state, with reference to its end or purpose, is contrary to the natural law. Now, a simultaneous plurality of wives upsets the sane balance and proportion of marriage with reference to its end; at least it does so in a secondary way. For, though children may be begotten of many wives, and well reared too, yet a peaceful and united family life,which pertains to the welfare of offspring (the chief end of marriage), is rendered impossible in such circumstances. Besides,simultaneous plurality of wives destroys that blessing of marriage called fidelity, which is the exclusive use of maritalrights by one husband and one wife. Further, if there be several wives, spouses cannot really be two in one flesh. For all these reasons, we say that simultaneous plurality of wives is in conflict with the natural law.

And yet this conflict with the natural law does not touch that law in its primary precepts, but in secondary ones. And,before the institution of matrimony as a sacrament, God, in the Old Law, permitted to some a plurality of wives-this, by way of exception. The primary requirement of the natural law respecting marriage is that offspring be generated, born, and well reared;this is the essential good of offspring; this can be attained even with plurality of wives.

It is certainly contrary to the natural law, as it isin conflict with Christian morality, for a man to have a concubineor mistress as well as a wife.

It is unquestionably a mortal sin for a man to make use of a concubine; this is plainly the terrible sin of adultery.

In the Old Testament, in cases where, by divinedispensation, plurality of wives was permitted, these wives were often called concubines, yet they were not really so in the accurate meaning of that term.