Asalamu alikum 
Polygyny in Islam
Marriage to more than one wife at the  same time - Polygyny 
3 -
  is a practice as old as the history of man, and is allowed in Islamic 
law. Among  others, Polygyny was well known to the Ancient Hebrews, 
Egyptians, Greeks,  Persians, Assyrians, Japanese, Hindus, Russians and 
Germanic peoples.
All previous revealed religions  practiced and condoned Polygyny. The
 Old and New Testaments are at the foremost  in the list of the 
religious Books that legalized and practiced it. Many of the  Prophets 
of Allah before Prophet Muhammad (Peace be upon Him) entered into plural
 marriages.  Prophet Abraham had two wives; Prophet Jacob had four 
wives; and Prophet David  had ninety-nine wives (may Allah exalt their 
mention). Prophet Solomon (may Allah exalt their mention) had seven 
hundred wives who were free  noble women, and three hundred other wives 
who were slave women. Nowhere does  the law of the Prophet Moses (may 
Allah exalt their mention) set or determine a specific number of  wives 
to which a husband was entitled. The compilers of the Talmud, who lived 
 around Jerusalem,  decided upon a certain number of wives for a man, 
and some Jewish scholars only  permitted a second wife or more if the 
first wife was permanently ill or  barren. Still other Jewish scholars 
did not permit plural marriages at all.
In the New Testament of the Bible,  Jesus is commissioned to comply 
with and complete the Laws of Moses (may Allah exalt their mention) 
and we cannot find a single quote in  the Bible that forbids plural 
marriage. The prohibition of plural marriages in  Christianity came 
about only as a result of legislation set forth certain  segments of the
 Christian church, and not by the original teachings of  Christianity 
itself.
For this reason we find many examples  of Christians taking multiple 
wives. The Irish king, Ditharmet, for instance,  had two wives. King 
Frederick the Second had two wives with the church's  approval. Thus, it
 must be noticed that prohibition was in the hands of the  priests of 
the church, and not in accordance with any universally recognized  
original law of Jesus Christ himself (may Allah exalt their mention). 
Martin Luther, the German priest who  first established the Protestant 
sect, considered plural marriage acceptable  and advocated it on many 
occasions. 
Polygyny was well known amongst pagan  Arab tribes prior to the 
advent of Islam but there was no limitation for the  number of wives, 
like in the cases of some of the Prophets mentioned above. With  the 
advent of Islam, the Islamic law condoned Polygyny but a man was limited
 to  only four wives, and specific rules regulated these marriages. 
There are  numerous examples in the authentic traditions wherein the 
Messenger of Allah (Peace be upon Him) obligated those who had more than
  four wives, when they accepted Islam, to choose four and divorce the 
rest  honorably. Allah,  the Most Beneficent, said: 
(And  if you fear that you shall not be able to deal 
justly with the orphan-girls,  then marry (other) women of your choice, 
two or three, or four but if you fear that you shall not  be able to 
deal justly (with them), then only one or (the captives  and the slaves)
 that your right hands possess. That is nearer to prevent you  from 
doing injustice.)
[4:3]
Thus we see that  strict justice and fairness in treatment, and 
avoiding any injustice and wrong  practices against all wives, is 
stipulated and conditional for those who wish  to take more than one 
wife. The  Messenger of Allah (Peace be upon Him) warned against  
favoritism saying: 
"He who has two wives and is not just between  them, he will come on the Day of Resurrection with one of his sides fallen." 
[Abu Dawood #2133 & Tirmidhi #1141 and verified]
Justice  and fairness, in this context, applies to material things 
such as expenditure,  fair division of wealth, gifts, time, etc. As for 
emotional matters, such as  love and inclination of the heart towards 
one wife over the other, it is  recognized that man has no control over 
his innermost heart and emotions, as they  are involuntary. Allah, the 
Most Beneficent, said: 
(You  will never be able to do perfect justice between 
wives even if it is your  ardent desire (i.e. emotions of the heart), so
 do not incline too much to one  of them (by giving her more of your 
time and provision) so as to leave the  other hanging (i.e. neither 
divorced nor married). And if you do  justice, and do all that is right 
and fear Allah by keeping away from all that  is wrong, then Allah is 
Ever OftForgiving, Most Merciful)
[4:129] 
Aishah, the mother of the believers and the  wife of the Prophet (Peace be upon Him), narrated: 
"The Prophet of  Allah (Peace be upon Him) would distribute everything justly amongst his wives,  then say: 
O Allah! This  is my division for what I possess, O Allah! Do not blame 
me for what You alone  possess while I do not (i.e.  emotions of the 
heart).
[Abu Da`wood, Tirmidhi others, but with a weak chain] 
A man who is impotent should not seek  any marriage since he is 
unable to fulfill its basic requirement. He who knows  for sure that he 
is financially incapable of supporting another wife and  household, is 
not allowed to seek another marriage, just as the bachelor who  seeks to
 marry must strive to earn the wherewithal and must be able to sustain  
his wife and future children. As Allah says, and which can be taken as a
  general rule:
(And  let those who find not the financial means for 
marriage keep themselves chaste,  until Allah enriches them with His 
Bounty.)
[34:33]  
Let us take a look of  some conditions that befall people of any 
society, and then assess whether  Polygyny is a good solution for the 
problems that occur, and also the practice  of Polygyny is in favor of a
 woman or against her! The following points prove  that monogamy in many
 situations leads to promiscuity, prostitution or divorce:
-  If a woman is sterile and the husband is interested in  having 
children, should he divorce the woman and marry a second wife? Or, if  
she chooses to stay married to him, should he take a second wife giving 
them  both equal rights as his lawful wives?
-  If a wife is chronically ill and cannot maintain her  marital 
relations with her husband, should he keep her and take a second wife  
wherein she remains perfectly honored, cared for and provided for by her
  husband? Or should he divorce her?
-  Some men are financially strong, and sexually demanding  and 
potent with higher levels of hormonal testosterone. One wife may not be 
 able to fulfill his lawful and natural sexual desire. If the menstrual 
period  or after-birth-confinement period is notably longer than normal,
 or if she has  no natural sexual desire to match that of the husband, 
or other scenarios, what  is better for both husband and wife in such a 
case? Is it better for the man to  remain frustrated and pent up, or 
seek unlawful sexual satisfaction outside the  marriage? Or to acquire 
other lawful wives who can help to keep him chaste and  satisfied?
-  In various parts of the world international and civil  wars and 
other catastrophes often take their toll on men more than women. Even  
naturally, the demographic number of females, for various reasons, is 
often  more than males in most countries. The best example of this is 
the case of the  First World War, and the Second World War, which 
claimed the lives of an astronomical  number of men who had participated
 in the fighting, with tens of millions of them  being killed. In other 
trouble spots the disproportionate death ratios are  similar. In such a 
case, if every man had only one wife, what would be the  necessary 
destiny of the women left without lawful marriage to satisfy their  
social, financial and sexual needs? Some women may be tempted to satisfy
 their  sexual desires in unlawful ways through fornication, lesbian 
activities or  prostitution, a destabilizing factor for any society. The
 abundance of women  without husbands, or male relatives to care and 
protect their interests, is one  factor that helps spread corruption and
 illegitimate sexual activities in  societies. What is better for a 
society and for such women in this case: to  remain single and suffer 
all the consequences of life without marriage; or to  accept to be a 
second wife with an honest, protective, honorable and chaste  man?
Promiscuity unfortunately exists in all  modern societies, but should
 it be legalized or condoned, as is the case under  man-made laws, with 
all the social consequences? In most contemporary societies  only 
monogamous marriage is legal, but extra martial relations are allowed as
 a  socially acceptable substitute for the situations mentioned above, 
in the form  of mistresses, girl friends, escort services, prostitution 
and common law  marriages. These types of relationships have no merits 
of their own to stand  on, and if the couple does not eventually get 
legally married, the illicit  relationship often leads to abuse and 
conflict. These illicit relationships are  only meant to fulfill sexual 
interests of the two parties involved without the  responsibilities, and
 abuse the rights of the women in general. Legally it  imposes no 
financial, social, or emotional obligations, and if the woman  becomes 
pregnant, it is her own problem, with the illegitimate children left  
without the support of a family and sometimes abandoned to the social 
service  system. Men, generally, are not obliged to admit the paternity 
of the child,  thus not obliged to take financial responsibility for the
 child. Abortions  proliferate in this kind of society. In accordance 
with Islamic law, a second,  third, or fourth wife enjoys all the rights
 and privileges of the first wife  without an iota of injustice or 
dishonor to her. 
Adultery, fornication and all  extramarital sexual relations are 
strictly forbidden in Islam and the prophet  took all measures to 
protect the society from these social diseases which, if they become 
widespread, can only bring harm and destruction upon individuals,  
families, and the basic bond holding the society together as a whole. 
The  following tradition shows the wisdom of the Prophet (Peace be upon 
Him) and patience in convincing a young  virile man, by eloquent 
analogies, the injustice of double standards and the  evils of wanton 
desires leading to fornication and adultery.No one  would want his own 
female relatives to be exploited, used and abused, so how, then,  can 
they allow themselves to exploit others?
An authentic tradition  narrates: 
"A young man  came to the Messenger of Allah (Peace be upon Him) and asked:
"O Messenger of Allah, permit me (with special license) to commit  fornication (and adultery)." 
The people started to rebuke him harshly, but the Prophet sat close to him and asked: "Would  you like it for your mother? 
He replied "No,  by Allah, may Allah make me a sacrifice for you!"
The Messenger of  Allah (Peace be upon Him) said: "And thus the people do not like it for their  mothers," and continued: 
"Would you like it for your daughter?"
"No" he replied. 
The Messenger of  Allah (Peace be upon Him) said: "And thus the people do not like it for their  daughters," and continued: 
Would you like it for your paternal aunt?" 
"No" he replied. 
The Messenger of  Allah (Peace be upon Him) said: "And thus the people do not like it for their  paternal aunts," and asked: 
"Would you like it for your maternal aunt?" 
"No" he replied. 
The Messenger of  Allah (Peace be upon Him) said: "And thus the people
 do not like it for their  maternal aunts." Then the Prophet (Peace be 
upon Him) put his hand on the youth and said: 'O  Allah forgive his sin 
and purify his heart and make him chaste (fortify his  abstinence from 
sexual sins).
[Ahmad #22265 and verified]
One might say that this tradition is a  practical application of the 
golden rule as mentioned by the Messenger of Allah  (Peace be upon Him):
 
"None of you [truly] believes until he loves for  his brother that which he loves for himself."
[Bukhari #15 & Muslim #44]
Polygyny in the Islamic society is  limited to four wives only; the 
marriages being performed lawfully with a  proper marriage contract, 
witnesses, etc. The man must bear all financial  burdens and 
responsibilities to his wives and children that arise from his  
marriages. All the children are legitimate and must be raised and cared 
for  under the responsibility of both parents. 
One might ask that, if we permit Polygyny  for men, why is not polyandry
 permitted for women? The answer to this question is simple since 
numerous  natural and physical reasons, as indicated above, preclude 
this as a viable  option. Men in almost all societies of the world have 
the position, domination  and authority over the households due to their
 natural endowment and strength. Even  if, for argument's sake, we 
forego the idea of their strength and suppose that  a woman has two or 
more husbands, the question will arise: who will have the  ultimate 
authority and leadership of the home - as this would create harmful  
competition, jealousy, anger and hatred among the husbands and result in
 great  destruction in the society.
Moreover, if a woman were allowed to be married to  more than one 
man, who would be the legal father of the child she bears, and  how 
would fatherhood be convincingly determined? What would happen to the  
demography of the society after some generations of this arrangement? 
Would the  men be able to remain chaste within their marriage vows in 
such an arrangement  with one wife, or would he be tempted into 
promiscuity? The answers to all  these questions are obvious. Since a 
woman can only become pregnant  approximately once a year and she can 
get pregnant by only one man at a time,  while a man can naturally 
impregnate more than one woman on a continual basis,  it follows that it
 is more logical and natural that the man has more than one  wife and 
that she doesn't engage more than one husband.
Above all in Polygyny, the man is  responsible for the provision of 
all of his wives and children, which keeps  everything in order, while 
this is not the case in polyandry, thus impractical  from any 
conceivable angle whatsoever. The following are statements of some  
Western thinkers who demanded Polygyny and considered it the only 
solution for  the problems they were confronted with in their societies.
Gustav Le Bon, the well-known French thinker, says  in his book Arabic Civilization: 
"Polygyny enables the society to reduce  social crisis,
 prevents the mistress problem and cures the society from illegitimate  
children."
Annie Besant, in her book on Indian Religions says: 
"I read in the Old Testament that the  closest friend 
to Allah, whose heart acts upon the Will of Allah, was polygynous.  
Moreover, the New Testament did not forbid Polygyny except for priests 
or  ministers of the church, who were required to keep and maintain one 
wife only.  Old Indian religious books also permitted Polygyny. It is 
easy, however, to  criticize others in their religious practices. And 
that is what made people  accuse Islam and attack it for its permission 
of Polygyny. However, it is  strange that Westerners are against the 
restricted and limited Polygyny of the  Muslims, while they suffer from 
wide scale prostitution and promiscuity in  their own societies. A close
 examining look at the Western society illustrates  that only a few 
pure, chaste and honest men respect their clean marital  relationships 
and honor their marriage to one single wife and have no other  sexual 
relationship outside marriage. It is an incorrect and inaccurate  
statement, therefore, to describe a community as monogamous, in which 
the men  maintain a single marriage, while they are indeed having 
mistresses, girl  friends and other means of sexual relationship outside
 the marriage to their  legal and lawful wife.
If we were to be fair and just, we could see that 
Polygyny  in Islam protects, honors, maintains and respects women in 
society. Polygyny is  better than the Western prostitution that permits a
 man to have a mistress or a  girl friend to fulfill his sexual desires 
with no respect to the feelings,  emotions, needs and honor of the 
women. The man will disown that woman as soon  as he gets his 
satisfaction. The man has no social commitment or obligation  towards 
the mistress or the girl friend. She is only meant to fulfill his  
sexual needs of the moment and give him the company he needs 
temporarily. Even  though some people declare both Polygyny and 
fornication or prostitution as bad  and unacceptable, yet it is unfair 
for the non-Muslims to blame a Muslim for  doing the same thing that he 
does while his society accepts and condones  it."
Jawad, a well-known English scholar, says: 
"The stiff British system which  prevents Polygyny is 
an unfair and unacceptable system. It severely hurts  approximately two 
million women who have become old maids. These women have  lost their 
youth and were deprived of having children. Thus, these women were  
forced to throw away the moral values as one throws away the pit of a  
date." 
Mobenar, a member of the previous French  Parliament noted: 
"There are two and a half million  French girls now who
 cannot find a husband, if we assume that every French  young man will 
marry only one woman. I frankly declare what I truly believe is  that a 
woman will not enjoy a healthy life unless she becomes a mother. I  
believe that any law which passes a judgment that such a big number of 
the  members of a society should live opposing, contradicting and 
neglecting to  fulfill the natural laws of man on the Earth is but a 
cruel and savage law that  contradicts the simplest meaning of justice 
and fairness." 
In 1959, the United  Nations published a special publication stating: 
"This publication has proven, by  numbers and statistics, that the 
entire world is now facing a growing problem  of illegitimate children, 
as opposed to legitimate children. The number of  illegitimate children 
has increased 60% in some countries. In Panama, for  instance, the 
percentage of illegitimate births soared to 75% of the total  number of 
births in the country. This means that three out of every four  children
 are illegitimate, born outside of wedlock. The highest percentage of  
illegitimate births is stated to be in Latin America." 
At the same time, the publication  proves and indicates
 that the number of illegitimate births in the Islamic  world is almost 
nil (in comparison with other countries). The editor of the  publication
 goes on to say that Islamic countries are protected against such  
social problems and disease due to the fact that the people practice 
Polygyny.