Why Can Muslim Men Marry Up to Four Wives?

"If you fear you might fail to give orphan women their due rights if you were to marry them, then marry other women of your choice—two, three, or four. But if you are afraid you will fail to maintain justice, then content yourselves with one or those bondwomen in your possession. This way you are less likely to commit injustice" (Quran 4:3)

Polygamy is a marriage system that allows one person to marry more than one spouse. This system of the marital union comes in two varieties. In a union of polyandry, a woman marries more than one man, which is not permissible in Islam - and for good reason. The other type is polygyny, a system where a man marries more than one woman, a union acceptable in Islam with certain restrictions. 

When the Holy Quran came down, polygyny was practiced in Arabia. Islam did not introduce the concept of polygyny; instead, the faith sanctioned regulations and restrictions in a society with no limit imposed on the number of women a man could marry simultaneously. These restrictions were intended to protect women and restore justice. Islam did not mandate polygyny, nor did the faith encourage it.  

At a time in Arabia when men guardians would marry numerous orphans in their custody without regard or offer them their fair dower. And after battles in which multiple male casualties occurred, leaving widows and female orphans without guardians, the Holy Quran revealed guidance regarding the fair treatment of female orphans to ensure they get fair treatment, their fair share of a dower, and not get taken advantage of.   

Marriage in Islam is a transfer of responsibility from the father to the husband, ensuring the husband will provide for the woman involved. In special cases, the Holy Quran allows a man to marry a female orphan, affording a higher likelihood that the man will accept his financial responsibility toward her. 

The Holy Quran states if one can treat each wife fairly and equally, he can marry up to four wives. Whereas Allah allows polygyny, He says in the same chapter that it will never be possible for a husband to treat all his wives with equitable fairness. He warns men to exercise caution before entering a polygeny relationship, as it is no easy task to treat multiple wives fairly and do them all justice. In such a relationship, men can encounter problems with their wives and Allah. This issue limits the possibility of polygyny in societies. Thus, Allah indirectly implies that monogamy is preferred in most cases. 

"You will never be able to maintain emotional justice between your wives—no matter how keen you are. So do not totally incline towards one leaving the other in suspense. And if you do what is right and are mindful of Allah, surely Allah is All-Forgiving, Most Merciful." (Quran 4:129) 

Polygyny is not a required marital state; it's optional. A tiny percentage of Muslims practice polygyny. Some Muslim countries prohibit polygyny, some restrict it, and some allow it. Whereas the practice has its negative aspects, its positives and benefits outweigh the negatives, and the union resolves issues facing certain societies. Polygyny may not be suitable for everyone at their current place and time, but it sometimes makes sense to marry more than one wife. 

While monogamy is generally the preferred norm for contemporary marriages, certain societies in the past boasted more female residents than men because of the high mortality rate of men dying in war or from violent crimes. Some communities have seen female residents outliving their spouses due to the latter being exposed to dangerous occupations or activities that put their health at risk or because women generally boast stronger immune systems than men.