Let us look at some of the verses from the Old Testament that allow polygamy:
In Exodus 21:10, a man can marry an infinite amount of women without any limits to how many he can marry.
In 2 Samuel 5:13; 1 Chronicles 3:1-9, 14:3, King David had six wives and numerous concubines.
In 1 Kings 11:3, King Solomon had 700 wives and 300 concubines.
In 2 Chronicles 11:21, King Solomon's son Rehoboam had 18 wives and 60 concubines.
In Deuteronomy 21:15 "If a man has two wives, and he loves one but not the other, and both bear him sons...."
There are a lot more verses from the Old Testament that allow polygamy, but I think that the above are sufficient enough to prove my point.
I don't know what point James is trying to make but he did remind me of something that I've been thinking about for several months now. While the Bible does report that many of the patriarchs had more than one wife no where do I recall seeing any indication that God considered this to be a good thing. Let's take a look at the verses so conveniently provided by James (thank you by the way).
Exodus 21:10 states, "If he takes another wife to himself, he shall not diminish her food, her clothing, or her marital rights." If a man takes another wife he is not allowed to mistreat her. It does not say that he should take another wife or that it is good for him to take another wife or that God is pleased by him taking another wife.
2 Samuel 5:13 states, "And David took more concubines and wives from Jerusalem, after he came from Hebron, and more sons and daughters were born to David." 1 Chronicles 3:1-9 lists the children born to David at Hebron. 1 Chronicles 14:3 states, "And David took more wives in Jerusalem, and David fathered more sons and daughters." Nowhere and at no time does it say that any of David's wife and concubine taking were approved by God. Any reading of the passages that recount David's life should reveal the dysfunctional nature of his family that stems from the fact that he had so many wives and concubines. At one point in his life David was on the run from his own son Absalom. Beginning with the rape of one of David's daughters by one of David's sons in 2 Samuel 13 Absalom waged a struggle for his father's throne that ended with Absalom's death in 2 Samuel 18.
1 Kings 11:3 not only tells the number of Solomon's wives and concubines but that they "turned away his heart." In fact 1 Kings 11:1-8 clearly describes Solomon's folly in having so many wives. Verse 4 says, "For when Solomon was old his wives turned away his heart after other gods, and his heart was not wholly true to the LORD his God, as was the heart of David his father." That really doesn't sound like God approved of Solomon's polygamy.
2 Chronicles 11:21 tells us that Rehoboam, Solomon's heir, "loved Maacah the daughter of Absalom above all his wives and concubines (he took eighteen wives and sixty concubines, and fathered twenty-eight sons and sixty daughters)." Again there is no indication that Rehoboam's polygamy was a good thing for him, his wives, or his children and there is certainly no sign of approval from God. In addition to this Rehoboam's rule marked the beginning of the downward spiral of the nation of Israel that led to them being carted off into exile. Not the best argument for polygamy to me.
Deuteronomy 21:15-17 states, "If a man has two wives, the one loved and the other unloved, and both the loved and the unloved have borne him children, and if the firstborn son belongs to the unloved,[a] 16then on the day when he assigns his possessions as an inheritance to his sons, he may not treat the son of the loved as the firstborn in preference to the son of the unloved, who is the firstborn, 17but he shall acknowledge the firstborn, the son of the unloved, by giving him a double portion of all that he has, for he is the firstfruits of his strength. The right of the firstborn is his." Again note the if at the beginning of this passage. There is no commandment that a man should have two wives. There is, however, a clear recognition of the damage that can be done to wives and children when polygamy is practised. This passage seeks to prevent one kind of strife that can occur in a polygamous family.
I could also mention Abraham's dysfunctional polygamous family and the self destructive nature of Jacob's polygamous family and how the dysfunction followed the family through generation after generation but I think that would be overkill at this point.
After much contemplation of scripture I have had to conclude that anyone who thinks that polygamy was okay or something that we should do today based on what the Bible says about it just isn't reading very carefully or doesn't care what the Bible actually says. Polygamy is a bad deal all around and the Bible gives many clear illustrations of how and why.