Gospel Topics: Latter-day Saints do not understand all of God’s purposes for instituting, through His prophets, the practice of plural marriage during the 19th century

"Plural Marriage and Families in Early Utah," Gospel Topics on LDS.org:

Latter-day Saints do not understand all of God’s purposes for instituting, through His prophets, the practice of plural marriage during the 19th century. The Book of Mormon identifies one reason for God to command it: to increase the number of children born in the gospel covenant in order to "raise up seed unto [the Lord]" (Jacob 2:30). Plural marriage did result in the birth of large numbers of children within faithful Latter-day Saint homes. It also shaped 19th-century Mormon society in other ways: marriage became available to virtually all who desired it; per-capita inequality of wealth was diminished as economically disadvantaged women married into more financially stable households; and ethnic intermarriages were increased, which helped to unite a diverse immigrant population. Plural marriage also helped create and strengthen a sense of cohesion and group identification among Latter-day Saints. Church members came to see themselves as a "peculiar people," covenant-bound to carry out the commands of God despite outside opposition, willing to endure ostracism for their principles.^[1]

What do the scriptures say about plural marriage?

The only scriptural explanations given from the Lord for approved plural marriage are found in Jacob 2:30 and D&C 132

Many have asked what the scriptures say about the reasons the Lord gave for plural marriage. All such reasons are outlined in this article.

Raise Up A Faithful Seed

"For if I will, saith the Lord of Hosts, raise up seed unto me, I will command my people; otherwise they shall hearken unto these things."

Here, the Lord gives one reason for plural marriage, "to raise up seed unto me."

Restoration of All Things

As Latter-day Saint scholar Brian Hales has written:

The earliest justification mentioned by the Prophet was as a part of the "restitution of all things" prophesied in Acts 3:19–21. Old Testament prophets practiced polygamy, so it could be a part of the restoration of "all things" (see D&C 132:40, 45).

[. . .]

Joseph Smith was a prophet-restorer, which helps to explain why the command to practice plural marriage has been labeled a "restoration," even though it is not a salvific ordinance.

Making Marriage Available to Everyone

Again from Brian Hales:

The fourth reason Joseph Smith gave for the practice of plural marriage dwarfs the other three explanations in significance because it deals with eternity. The message of D&C 132:16–17 states that men and women who are not sealed in eternal marriages during this life (or vicariously later) "remain separately and singly, without exaltation, in their saved condition, to all eternity."

In other words, "exaltation," the highest salvation, requires eternal marriage. No unmarried person can be exalted according to Joseph Smith’s teachings.

Multiply and Replenish the Earth

In the only recorded revelation on plural marriage received by Joseph Smith, the Lord further stated (D&C 132:63):

"they [the plural wives] are given unto him to multiply and replenish the earth, according to my commandment, and to fulfil the promise which was given by my Father before the foundation of the world, and for their exaltation in the eternal worlds, that they may bear the souls of men; for herein is the work of my Father continued, that he may be glorified."

This passage suggests that plural marriage served the purpose of multiplying and replenishing the earth.

Abrahamic Test

D&C 132:34-36 reads:

34 God acommanded Abraham, and Sarah gave bHagar to Abraham to wife. And why did she do it? Because this was the law; and from Hagar sprang many people. This, therefore, was fulfilling, among other things, the promises.

35 Was Abraham, therefore, under condemnation? Verily I say unto you, Nay; for I, the Lord, commanded it.

36 Abraham was commanded to offer his son Isaac; nevertheless, it was written: Thou shalt not kill. Abraham, however, did not refuse, and it was accounted unto him for righteousness.

This scripture suggests that one of the purposes of polygamy was to provide an Abrahamic-like test for the early Saints. Many people recalled how difficult it was to practice polygamy.

Hellen Mar Kimball recalled:

I did not try to conceal the fact of its having been a trial, but confessed that it had been one of the severest of my life; but that it had also proven one of the greatest of blessings. I could truly say it had done the most towards making me a Saint and a free woman, in every sense of the word; and I knew many others who could say the same, and to whom it had proven one of the greatest boons—a ‘blessing in disguise.'^[2]

Plural marriage can be a difficult historical fact for people to understand, both members and nonmembers alike

It is often not the Lord's pattern to give a multitude of reasons for His commandments, and we are often left to draw our own conclusions—which may be completely wrong (Moses 5꞉6-8). We often obey when we do not understand why a command has been given—we only know that it has been given. We should remember the caution of Elder Dallin H. Oaks:

...It's not the pattern of the Lord to give reasons. We can put reasons to commandments. When we do we're on our own. Some people [have] put reasons to [commandments] and they turned out to be spectacularly wrong.^[3]

Trying to fully understand the purposes behind such a commandment in today's mindset can also make this subject difficult. It is important to note that we do not have all the historical information surrounding the inception and implementation of the practice. Rather than trying to understand the Lord's purposes in retrospect on a limited scope, one should remember the above scriptures in Jacob and D&C 132. Other benefits, although potentially advantageous, are not given as reasons by the Lord.

If the only purpose of polygamy was to "raise up seed," then why did Joseph not have children by his plural wives?

Polygamy was not permitted only for the purpose of procreation

If the only purpose of polygamy, at least in Joseph Smith's case, was to "raise up seed," then why did Joseph not have children by his plural wives? He was certainly capable of having children, as demonstrated by those that he had by Emma, many of whom died. Yet, there is no conclusive evidence to date of Joseph having had children by any of his plural wives, and DNA testing has ruled out most of those who were suspected of being such.

Joseph was commanded to restore the practice of polygamy as part of the "restoration of all things." It was obviously not intended that Joseph use the practice to produce progeny.

Joseph was also sealed for eternity to some women who were already married, but these women continued to have children by their current husbands

Among Joseph's plural marriages and/or sealings, between eight to eleven of them were to women who were already married. Of the eight well-documented cases, five of the husbands were Latter-day Saints, and the other three were either not active in or not associated with the Church. In all cases, these women continued to live with their husbands, most of them doing so until their husbands died. These eternal marriages appear to have had little effect upon the lives of the women involved, with the exception that they would be sealed to Joseph in the afterlife rather than to their earthly husbands. No children from these marriages have ever been identified. These were sealings which would only affect Joseph's association with these women in the afterlife.