All mandates of the religion of Islam are from God, the Wise, and thus one deduces that all things which are permitted are due to the fact that their benefit to the self and society outweighs their harms. When one analyzes the reasons and results of the allowance of polygamy, it will be found that indeed the rulings of the religion of Islam are truly those which suits all times and places, as their source is God Almighty, the Wise and the Knowledgeable.
As the Quran indicates (4:3), the issue of polygamy in Islam is understood in the light of community obligations towards orphans and widows. Islam, as a universal religion that is suitable for all times and places, can not ignore these compelling obligations.
Islamic polygamy addresses the social problems of prostitution and extramarital affairs common in the West. Instead of cheating – infidelity is one of the top reasons for divorce in the West – Islam allows a man to marry more than one wife, with full recognition of the rights of both of them. The basic principle in Islam is that men are held responsible for their behavior towards women just as women are responsible for their behavior towards men.
The number of women in the world exceeds that of men. The surplus is a result of men dying in wars, violent crimes, and women outliving men.  The upsurge in homosexuality further increases the problem. Bertrand Russell wrote, “And in all countries where there is an excess of women, it is an obvious injustice that those women who, by arithmetical necessity, must remain unmarried should be wholly debarred from sexual experience.”  Polygamy, then, is the only responsible solution for this predicament.
|Country ||Male Population||Female Population|
Let us take the US as an example. Why are extramarital affairs so widespread? “What makes this state of affairs possible, of course, is a supply of willing women. Most are single, both because of the growing numbers of unmarried women (there are 34 million in the United States today) and because single women generally have more free time and energy than do their married counterparts. Consider these statistics: One out of every five women today has no potential mate because there are simply not enough single men to go around. A 25-year-old single woman faces a serious undersupply of available men to start with, and the situation gets worse the older a woman gets. Divorced men are much more likely than divorced women to remarry (and they tend to marry younger women), so that there are more than twice as many single women as there are single men in their 40s. Indeed, a woman who divorces at 35 today is likely to remain single for the rest of her life. Caught in a demographic bind while seeking greater autonomy, more and more single women are opting for involvement with married men.” 
In addition, surplus of women who are not financially maintained by a husband is a cause of increased prostitution in the society. For example, Germany has 0.96 males/female. Under Germany’s welfare reforms, any woman under 55 who has been out of work for more than a year can be forced to take an available job – including being a prostitute in the sex industry – or lose her unemployment benefit!  A 1994 study found that 16% of 18-59 year old men in a US survey group had paid for sex (Gagnon, Laumann, and Kolata 1994).
Furthermore, the problem of the unbalanced sex ratios can worsen during times of war. The WWII war-bride phenomenon is a case in point. After the WWII there were 7,300,000 more women than men in Germany alone (3.3 million of them were widows). There were 100 men aged 20 to 30 for every 167 women in that age group. Many of these women needed a man not only as a companion but also as a provider for the household in a time of unprecedented misery and hardship. The soldiers in the victorious Allied Armies exploited these women’s vulnerability. Many young girls and widows had liaisons with members of the occupying forces. Many American and British soldiers paid for their pleasures in cigarettes, chocolate, and bread. 
Polygamy is an alternative to divorce in case of some marital problems. Instead of divorcing a sick or infertile wife, Islam permits a man to marry another woman while taking care of the first if she chooses to stay with him.
The teachings of Islam, including polygamy, conform to human nature. Men and women differ in their desire for sexual variety. These differences are universal. According to evolutionary scientists men are “hard-wired” to spread their seed. Men everywhere – whether single or married – want more sexual partners than women do. The Islamic solution provides the only responsible alternative to the naturally ingrained desire in men. 
There is a universal biological constraint in male and female reproduction. A woman’s reproductive capacity declines after her 20s and ends with menopause, but even a man in his 70s retains the ability to father children.  Polygamy is a solution for a man who desires more children, especially in traditional, agrarian societies. This may seem irrelevant in the Western context where childbearing is increasingly becoming independent of marriage. Polygamy is also an alternative for a man who desires to satisfy his natural sexual relations within the bounds of marriage, but whose wife may be averse to them due to age or sickness. Moreover, Islam prohibits sexual relations during a woman’s monthly cycles. Therefore, the prolonged menstrual period of the woman which prevents the husband from having sex with her, or a man whose sexual urge is not satisfied by one wife, may marry another. Islam permits such men to realize their desire within a legal framework, making them responsible for their sexuality, so he does not have to resort to cohabitation or prostitution.
Institutional polygamy controls the spread of sexually transmitted diseases like Herpes and AIDS. Such venereal diseases spread in promiscuous societies where extra-marital affairs and prostitution are widespread. This may be due to a husband’s bringing back the diseases he is infected with in an extramarital affair when he returns back to his ‘monogamous’ relationship with his wife.
One can clearly see that there are many benefits which result from the allowance of polygamy. Many societal ills are left untreated, if not created or worsened, due to modern restrictions placed on polygamy. One should not always regard their culture and time the most superior in history, but rather they should analyze customs, traditions and beliefs based on solid and tangible facts. When people do so, keeping and open mind and heart, they will draw nearer and nearer to the truth until it becomes clear as the light of day.
1) According to Center for Health Statistics, life expectancy of women in US is 77.9 years, while for men it is only 70.3.
2) Marriage and Morals, p. 47
3) The New Encyclopedia Britannica, vol. 17, pp. 34, 270, 244.
4) Laurel Richardson “Another World; More and More Single Women Are Opting for Affairs with Married Men, and the Trend Is Diminishing Feminist Progress,” Psychology Today, vol. 20, February 1986.
5) Clare Chapman, ‘If you don’t take a job as a prostitute, we can stop your benefits,’ The Telegraph, 30 Jan. 2005.
6) Ute Frevert, Women in German History: from Bourgeois Emancipation to Sexual Liberation (New York: Berg Publishers, 1988) pp. 257-264 as quoted by Dr. Sherif Abdel Azim, “Women in Islam Versus Women in the Judaeo-Christian Tradition: The Myth and The Reality.”
7) Schmitt, D.P., “Universal sex differences in the desire for sexual variety: Tests from 52 nations, 6 continents, and 13 islands,” Journal of Personality and Social Psychology, 85, 85-104. The study was conducted by Bradley University psychologist David Schmitt and published in the Journal of Personality and Social Psychology, was impressive in its scope: It involved 16,288 college students from 50 countries in the Americas, Europe, Africa, Asia, and Australia. (Source: http://www.bradley.edu/academics/las/psy/pdfs/schmitt%5B1%5D%5B1%5D.etal.2003.jpsp.pdf)
8) Bruce Bower, “Darwin’s Minds”, Science News Vol. 140 No. 15, October 12, 1991, p. 233-4.