Polygamy by the Numbers

Mickey Kaus has an item on Kausfiles related to the possible relationship between terrorism and -- polygamy. Kaus quotes William Tucker in the American Enterprise Online...

Today polygamy is not practiced widely in Islamic countries, and only accounts for about ten percent of all marriages. The country where the distribution of wives is most unequal—Saudi Arabia—seems to be the best at producing roving jihadists who roam the world in search of conflict.

But if polygamy isn't widely practiced in Islamic countries, can it really be so important that violent jihad is "unlikely to disappear until it is eliminated"?

Is the 10% “10% of men who are married”? In that case, the number of women in the society involved in polygamy could be much higher.

Here’s an oversimplified but clear analysis. Say the average number of wives-per-marriage is 4. Then 40% of the women who are married are involved in polygamy (assuming an equal male-female ratio in the population), and you’ve got 90% of the remaining men fighting for 60% of the women, leaving 30% of your male population with no hope of getting married. And that’s best-case, assuming none of the remaining 90% opt for polygamy at some point in the future.

The above assumes that everyone in the society either was (which obviously can’t be true in a polygamous society) or wants to get married. The next step would be to build in a factor related to the percentage of the society that actually is married. According to wording of the excerpt, 10% is not actually 10% of the total population; it is 10% of all marriages.

Assume 60% of the men are married. Then you have 6% of your men and 24% of the women (if you assume 4 wives per marriage) involved in polygamous marriages. Another 54% of both men and women are in monogamous marriages. The percentage of married women (monogamous + polygamous) with respect to the total population is 78%, leaving the 40% of unmarried men are fighting for 22% of the women, and 18% of the total male population permanently locked out of marriage.

Conclusion: Data on a) the average number of wives per marriage, and b) the percentage of the male Saudi population actually married is needed to further this discussion.