There has been a lot discussion as to the reasons behind the plural marriages of 19th century Mormons. Common in such discussions is reference to Jacob’s ardent proclamation on the godliness of monogamy and his associated caveat for raising up seed unto the Lord. The thought is that if the Lord wants a lot of Mormon babies, he’ll command the Saints to engage in polygamy. Without fail, one or more individuals will raise the fact that more children were born in monogamous marriages than in their polygamous counterparts (on a per marriage basis). I recently stumbled on a discourse by Brigham Young that spells out quite plainly his reasoning for polygamy, which corresponds well with Jacob and yet defies the modern criticism.
Brigham spoke in the Tabernacle on April 7th 1861 (JD 9:31) and offered an explanation of polygamy that contradicts many of his statements as to the eternal nature of its practice as well as his conflation with Adam-God. After complaining that many Mormons seem to want plural wives for reasons of “passion” he states:
If the plurality of wives is to pander to the low passions of men and women, the sooner it is abolished the better. "How far would you go in abolishing it?" I would say, if the Lord should reveal that it is his will to go so far as to become a Shaking Quaker, Amen to it, and let the sexes have no connection. If so far as for a man to have but one wife, let it be so…The time is coming when the Lord is going to raise up a holy nation. He will bring up a royal Priesthood upon the earth, and he has introduced a plurality of wives for that express purpose… And were I now asked whether I desired and wanted another wife, my reply would be, It should be one by whom the Spirit will bring forth noble children.
Here we see that Brigham places a heavy emphasis on the “royal Priesthood.” The ecclesiastical elite of nineteenth century Mormonism were all ordained Kings and Queens (with the highest leaders having the greatest kingdoms) and it was through this royal lineage that the Lord was to raise up his leaders. Young continues, highlighting again the utilitarian views of marriage by the early saints:
[To the Sisters]…Are you sealed to a good man? Yes, to a man of God. It is for you to bear fruit and bring forth, to the praise of God, the spirits that are born in yonder heavens and are to take tabernacles on the earth. You have the privilege of forming tabernacles for those spirits, instead of their being brought into this wicked world, that God may have a royal Priesthood, a royal people, on the earth. That is what plurality of wives is for, and not to gratify lustful desires–Do you look forward to that? or are you tormenting yourselves by thinking that your husbands do not love you? I would not care whether they loved a particle or not; but I would cry out, like one of old, in the joy of my heart, "I have got a man from the Lord!" "Hallelujah! I am a mother–I have borne an image of God!"
From this perspective we see that even though monogamous marriages had more children, the parents in such marriages were not yet “noble.” The best way to ensure the maximum progeny of royal lineage was to increase the amount of wives of those destined to reign on thrones in Celestial glory.