Orson Pratt argues for plural marriage on the basis that the biblical patriarchs practiced it, and that JS received revelation authorizing it.
Orson Pratt, "Celestial Marriage," The Seer 1, no. 1 (January 1853): 13–15
The doctrine of a Plurality of Wives was believed and practised by Abraham, the father of the faithful; and we find that while in this practice the angels of God frequently ministered to him, and at one time dined with him; and God manifested Himself to him, and entered into familiar conversation with him. Neither God nor His angels reproved Abraham for being a Polygamist, but on the contrary, the Almighty greatly blessed him and made promises unto him, concerning both Isaac and Ishmael, clearly showing that Abraham practiced what is called, Polygamy, under the sanction of the Almighty. Now if the father of the faithful was thus blessed, certainly it should not be considered irreligious for the faithful who are called his children to walk in the steps of their father Abraham. Indeed, if the Lord, Himself, through His holy prophets, should give more wives unto his servants, as He gave them unto the prophet David, it would be a great sin for them to refuse that which He gives.
. . .
From the foregoing Revelation, given through Joseph, the Seer, it will be seen that God has actually commanded some of His servants to take more wives, and has pointed out certain duties in regard to the marriage ceremony, showing that they must be married for time and for all eternity, and showing the advantages to be derived in a future state by this eternal union, and showing, still further, that, if they refused to obey this command, after having the law revealed to them, they should be damned. This revelation, then, makes it a matter of conscience among all the Latter-Day Saints; and they embrace it as a part and portion of their religion, and verily believe that they cannot be saved and reject it.
. . .
Those individuals who have strength of mind sufficient to divest themselves entirely from the influence of custom, and examine the doctrine of a Plurality of Wives under the light of reason and Revelation, will be forced to the conclusion that it is a doctrine of Divine origin; that it was embraced and practised under the Divine sanction, by the most righteous men who ever lived on the earth; holy Prophets and Patriarchs who were inspired by the Holy Ghost — who were enwrapt in the visions of the Almighty — who conversed with holy angels — who saw God face to face, and talked with Him as a man talks with his friend — were "Polygamists," that is, they had many wives — raised up many children by them — and were never reproved, by the Holy Ghost, nor by Angels, nor by the Almighty for believing in and practicing such a doctrine; on the contrary, each one of these ''Polygamists" received, by revelation, promises and blessings for himself, for his wives, and for his numerous children, born unto him by his numerous wives.