Against polygamy

A couple of days ago I got asked whether polygamy is immoral. Here's some biblical ruminations on the topic.

• God created Adam and Even (Gen. 2), not Adam and Eve and Rachel and Charlotte and...
• In the OT, polygamy always caused problems. Abraham's son through Hagar was not the child of the promise; Isaac, his son through Sarah his wife, was (Gen 17:15-22). Jacob wound up marrying Leah and Rachel because of Laban's deceit, but he loved Rachel more than Leah, and that caused tension and competition between the women (Gen ch 29-30).
• Song of Songs portrays exclusive love. "My lover is mine and I am his" (SoS 2:16; 6:3).
• Jesus validates one-man one-woman in Matt 19:5-6 & Mark 10:7-8, where he quotes the "one flesh" reference in Genesis 2:24.
• Paul requires monogamy from church leaders: 1 Tim 3:2, 12; Titus 1:6. This cannot be reserved for church leaders alone because they are supposed to be examples to the rest of the people: 1 Tim 3:15.

One way to dismiss all this is to say that polygamy was taken for granted in the Ancient Near East, so that's why the OT accepts polygamy. My response is: then why is

1. Genesis 2 monogamous?
2. the OT so negative in its portrayal of polygamy?

More foundationally: to read the bible this way - that because everyone else was into polygamy, the Israelites had to as well - is to not make a key false assumption: that the bible has to validate what was socially accepted. Or, to put it another way: it is to ignore the idea that the OT portrays polygamy in order to criticise it, and call God's people to live differently. Of course, if we're willing to consider that:

• God doesn't want his people to live like everyone else;
• But instead wants their lives to be distinctively shaped by his word;
• And God's word reflects his character, which is uniquely committed and loyal;

... then a critique of polygamy, and assertion of monogamy, makes a whole lot more sense.

Thoughts, anyone...?