Here are the Questions that Plutarch asked with my answering to most of them:
1. Does the Bible prohibit it? If you think that it does, just how explicitly does it do so? Does it call it an abomination like homosexuality (or male prostitution, if you want to split hairs) or the sacrifice of infants?
The Bible in the New Testament does Prohibit Polygamy among men who are in any Church Leadership Positions. The following is from the Apostle Paul, from 1 Timothy Chapter Three, within the New Testament:
1 Timothy 3 (New International Version)
1 Timothy 3:1-2 & 12:
Overseers and Deacons
1 Here is a trustworthy saying: If anyone sets his heart on being an overseer,[a] he desires a noble task. 2 Now the overseer must be above reproach, the husband of but one wife, temperate, self-controlled, respectable, hospitable, able to teach,
12 A deacon must be the husband of but one wife and must manage his children and his household well.
2. Does the Bible condone it?
The closest that the Bible comes to condoning Plural Marriage is in the Old Testament is concerning Levirate Marriages. the following is from Deuteronomy Chapter 25, within the Old Testament:
Deuteronomy 25 (New International Version)
Deuteronomy 25:5-10:
5 If brothers are living together and one of them dies without a son, his widow must not marry outside the family. Her husband's brother shall take her and marry her and fulfill the duty of a brother-in-law to her. 6 The first son she bears shall carry on the name of the dead brother so that his name will not be blotted out from Israel.
7 However, if a man does not want to marry his brother's wife, she shall go to the elders at the town gate and say, "My husband's brother refuses to carry on his brother's name in Israel. He will not fulfill the duty of a brother-in-law to me." 8 Then the elders of his town shall summon him and talk to him. If he persists in saying, "I do not want to marry her," 9 his brother's widow shall go up to him in the presence of the elders, take off one of his sandals, spit in his face and say, "This is what is done to the man who will not build up his brother's family line." 10 That man's line shall be known in Israel as The Family of the Unsandaled.
The Lord God of the Old Testament, allowed the Patriarchs and Prophets Abraham and Jacob to have more than one wife, but I don't know if the Lord God of the Old Testament condoned the Patriarchs Abraham and Jacob to have more than one wife. The Lord God of the Old Testament gave a Prohitibition against any of the men who would be serving as Israelite Kings from having many wives. The following is from Deuteronomy Chapter 17, within the Old Testament:
Deuteronomy 17 (New International Version)
Deuteronomy 17:14-17:
The King
14 When you enter the land the LORD your God is giving you and have taken possession of it and settled in it, and you say, "Let us set a king over us like all the nations around us," 15 be sure to appoint over you the king the LORD your God chooses. He must be from among your own brothers. Do not place a foreigner over you, one who is not a brother Israelite. 16 The king, moreover, must not acquire great numbers of horses for himself or make the people return to Egypt to get more of them, for the LORD has told you, "You are not to go back that way again." 17 He must not take many wives, or his heart will be led astray. He must not accumulate large amounts of silver and gold.
3. Is your revulsion to plural marriage based upon some extra-Biblical norm? If so, what is it?
How about the Book of Mormon. The following is from Jacob Chapter Two, within the Book of Mormon:
Jacob 2:23-24:
[23] But the word of God burdens me because of your grosser crimes. For behold, thus saith the Lord: This people begin to wax in iniquity; they understand not the scriptures, for they seek to excuse themselves in committing whoredoms, because of the things which were written concerning David, and Solomon his son.
[24] Behold, David and Solomon truly had many wives and concubines, which thing was abominable before me, saith the Lord.
The following is from Mosiah Chapter 11, within the Book of Mormon:
Mosiah 11:1-4 & 14:
[1] And now it came to pass that Zeniff conferred the kingdom upon Noah, one of his sons; therefore Noah began to reign in his stead; and he did not walk in the ways of his father.
[2] For behold, he did not keep the commandments of God, but he did walk after the desires of his own heart. And he had many wives and concubines. And he did cause his people to commit sin, and do that which was abominable in the sight of the Lord. Yea, and they did commit whoredoms and all manner of wickedness.
[3] And he laid a tax of one fifth part of all they possessed, a fifth part of their gold and of their silver, and a fifth part of their ziff, and of their copper, and of their brass and their iron; and a fifth part of their fatlings; and also a fifth part of all their grain.
[4] And all this did he take to support himself, and his wives and his concubines; and also his priests, and their wives and their concubines; thus he had changed the affairs of the kingdom.
[14] And it came to pass that he placed his heart upon his riches, and he spent his time in riotous living with his wives and his concubines; and so did also his priests spend their time with harlots.
The following is from Ether Chapter Ten, within the Book of Mormon:
Ether 10:5-7:
[5] And it came to pass that Riplakish did not do that which was right in the sight of the Lord, for he did have many wives and concubines, and did lay that upon men's shoulders which was grievous to be borne; yea, he did tax them with heavy taxes; and with the taxes he did build many spacious buildings.
[6] And he did erect him an exceedingly beautiful throne; and he did build many prisons, and whoso would not be subject unto taxes he did cast into prison; and whoso was not able to pay taxes he did cast into prison; and he did cause that they should labor continually for their support; and whoso refused to labor he did cause to be put to death.
[7] Wherefore he did obtain all his fine work, yea, even his fine gold he did cause to be refined in prison, and all manner of fine workmanship he did cause to be wrought in prison. And it came to pass that he did afflict the people with his whoredoms and abominations.
Please Notice that all of those Passages I provided and quoted here within the Book of Mormon, all refer to having many wives as abominable or as an abomination. Remember also that Joseph Smith, Brigham Young and Heber C. Kimball all had many wives. Joseph Smith had at least 28 wives. Brigham Young had at least 27 wives. And Heber C. Kimball had at least 28 wives. They all truly had many wives. And having many wives is considered an abomination before the Lord God, according to the Book of Mormon. The Polygamy practiced by Joseph Smith, BY, And HBC was indeed an abomination before the Lord God according to the Book of Mormon.