Polygamy means a system of marriage whereby one person has more than one spouse. Polygamy can be of two types. One is polygyny where a man marries more than one woman, and the other is polyandry, where a woman marries more than one man. In Islam, limited polygyny is permitted; whereas polyandry is completely prohibited.
Now coming to the original question, why is a man allowed to have more than one wife?
Quran says marry only one:
The Qur’an is the only religious book, on the face of this earth, that contains the phrase ‘marry only one’. There is no other religious book that instructs men to have only one wife. In none of the other religious scriptures, whether it be the Vedas, the Ramayan, the Mahabharat, the Geeta, the Talmud or the Bible does one find a restriction on the number of wives. According to these scriptures one can marry as many as one wishes. It was only later, that the Hindu priests and the Christian Church restricted the number of wives to one.
Many Hindu religious personalities, according to their scriptures, had multiple wives. King Dashrat, the father of Rama, had more than one wife. Krishna had several wives.
In earlier times, Christian men were permitted as many wives as they wished, since the Bible puts no restriction on the number of wives. It was only a few centuries ago that the Church restricted the number of wives to one.
Polygyny is permitted in Judaism. According to Talmudic law, Abraham had three wives, and Solomon had hundreds of wives. The practice of polygyny continued till Rabbi Gershom ben Yehudah (960 C.E to 1030 C.E) issued an edict against it. The Jewish Sephardic communities living in Muslim countries continued the practice till as late as 1950, until an Act of the Chief Rabbinate of Israel extended the ban on marrying more than one wife.
Hindus are more polygynous than Muslims:
The report of the ‘Committee of The Status of Woman in Islam’, published in 1975 mentions on page numbers 66 and 67 that the percentage of polygamous marriages between the years 1951 and 1961 was 5.06% among the Hindus and only 4.31% among the Muslims. According to Indian law only Muslim men are permitted to have more than one wife. It is illegal for any non-Muslim in India to have more than one wife. Despite it being illegal, Hindus have more multiple wives as compared to Muslims. Earlier, there was no restriction even on Hindu men with respect to the number of wives allowed. It was only in 1954, when the Hindu Marriage Act was passed that it became illegal for a Hindu to have more than one wife. At present it is the Indian Law that restricts a Hindu man from having more than one wife and not the Hindu scriptures.
Let us now analyse why Islam allows a man to have more than one wife.
Qur’an permits limited polygyny:
As I mentioned earlier, Qur’an is the only religious book on the face of the earth that says ‘marry only one’. The context of this phrase is the following verse from Surah Nisa of the Glorious Qur’an:
“Marry women of your choice, two, or three, or four; but if ye fear that ye shall not be able to deal justly (with them), then only one.”[[Al-Qur’an 4:3]
Before the Qur’an was revealed, there was no upper limit for polygyny and many men had scores of wives, some even hundreds. Islam put an upper limit of four wives. Islam gives a man permission to marry two, three or four women, only on the condition that he deals justly with them.
In the same chapter i.e. Surah Nisa verse 129 says:“Ye are never able to be fair and just as between women….” [Al-Qur’an 4:129]
Therefore polygyny is not a rule but an exception. Many people are under the misconception that it is compulsory for a Muslim man to have more than one wife.
Broadly, Islam has five categories of Do’s and Don’ts:
‘ Fard’ i.e. compulsory or obligatory
‘ Mustahab ‘ i.e. recommended or encouraged
‘ Mubah ‘ i.e. permissible or allowed
‘ Makruh ‘ i.e. not recommended or discouraged
‘ Haraam ‘ i.e. prohibited or forbidden
Polygyny falls in the middle category of things that are permissible. It cannot be said that a Muslim who has two, three or four wives is a better Muslim as compared to a Muslim who has only one wife.
Average life span of females is more than that of males:
By nature males and females are born in approximately the same ratio. A female child has more immunity than a male child. A female child can fight the germs and diseases better than the male child. For this reason, during the pediatric age itself there are more deaths among males as compared to the females. During wars, there are more men killed as compared to women. More men die due to accidents and diseases than women. The average life span of females is more than that of males, and at any given time one finds more widows in the world than widowers.
India has more male population than female due to female feticide and infanticide:
India is one of the few countries, along with the other neighboring countries, in which the female population is less than the male population. The reason lies in the high rate of female infanticide in India, and the fact that more than one million female foetuses are aborted every year in this country, after they are identified as females. If this evil practice is stopped, then India too will have more females as compared to males.
World female population is more than male population:
In the USA, women outnumber men by 7.8 million. New York alone has one million more females as compared to the number of males, and of the male population of New York one-third are gays i.e sodomites. The U.S.A as a whole has more than twenty-five million gays. This means that these people do not wish to marry women. Great Britain has four million more females as compared to males. Germany has five million more females as compared to males. Russia has nine million more females than males. God alone knows how many million more females there are in the whole world as compared to males.
Restricting each and every man to have only one wife is not practical:
Even if every man got married to one woman, there would still be more than thirty million females in U.S.A who would not be able to get husbands (considering that America has twenty five million gays). There would be more than four million females in Great Britain, 5 million females in Germany and nine million females in Russia alone who would not be able to find a husband.
Suppose my sister happens to be one of the unmarried women living in USA, or suppose your sister happens to be one of the unmarried women in USA. The only two options remaining for her are that she either marries a man who already has a wife or becomes public property. There is no other option. All those who are modest will opt for the first.
In Western society, it is common for a man to have mistresses and/or multiple extra-marital affairs, in which case, the woman leads a disgraceful, unprotected life. The same society, however, cannot accept a man having more than one wife, in which women retain their honorable, dignified position in society and lead a protected life.
Thus the only two options before a woman who cannot find a husband is to marry a married man or to become public property. Islam prefers giving women the honorable position by permitting the first option and disallowing the second.
There are several other reasons, why Islam has permitted limited polygyny, but it is mainly to protect the modesty of women.