Why does Islam permit polygamy?

According to global statistics, the male and female birth rates are almost equal. However, it is scientifically acknowledged that the rates of females' survival are higher than those of males. Moreover, in wars more men get killed than women. It is also scientifically proven that the average age of females is bigger than that of men which, consequently, leads to increasing the rate of widows globally than that of widowers. Thus, women will come to constitute the majority of the world population and that is why it is not practically appropriate to restrict every man to one wife.

In societies where polygamy is legally forbidden, we find it common for men to have mistresses and several intimate relations out of wedlock, which is an implicit, yet illegal, approval of polygamy. This was a predominant phenomenon before Islam, and Islam came to rectify this situation and preserve the woman's rights and dignity, turning her from a mistress to a self-respecting wife, enjoying her and her children's rights.

It is quite astonishing that these societies find no trouble in accepting affairs out of wedlock, or even same-sex marriages, and accepting relationships void of clear responsibilities, as well as accepting fatherless children. However, such societies can by no means accept a legal marriage between a man and more than one woman. Islam, on the other hand, shows great wisdom in this regard and clearly permits man to practice polygamy, for the sake of preserving the woman's dignity and rights, so long as he has less than four wives and the two conditions of justice and ability are met. Polygamy also aims at solving the problem of the woman who cannot find a single husband and has no choice except to get married to a married man or accept to be someone's mistress.

Despite the fact that Islam allows polygamy; yet, it is not true that a Muslim man is forced to marry more than one as some may believe.

{If you fear that you may not maintain justice with orphan girls [by marrying them] then marry women of your choice – two, three, or four; but if you fear that you may not maintain justice, then marry only one...} [208] Surat an-Nisā’: 3.

Actually, the Qur’an is the only religious book in the whole world that clarifies the fact that one must have only one wife in case the condition of justice cannot be met.

{You will never be able to maintain absolute justice between your wives, no matter how keen you are. So do not completely incline to one leaving the other in suspense. If you do what is right and fear Allah, Allah is surely All-Forgiving, Most Merciful.} [209] Surat an-Nisā’: 129.

In all cases, a woman is entitled to be her husband's only wife by mentioning such condition in the marriage contract, which is an essential and binding condition that must not be revoked.