Is there any prerequisite for a Muslim before going for second, third or fourth marriage or is polygamy/polygny permitted in any circumstances in Islam?
As far as I have been with scholars and studied the Qur'an and Sunnah I have not come across any such particular reason for going into polygamy. And Allah has said in the Quran [4:3]:
then marry those that please you of [other] women, two or three or four. But if you fear that you will not be just, then [marry only] one or those your right hand possesses. That is more suitable that you may not incline [to injustice].
You may like any girl, whilst you are married, and so you can marry her too. Or that you like to support someone, so you may marry her. Or there can be any reason for marrying, be it wise or not. Islam has allowed men to have at max four wives at one time, and there are no prerequisites attached to it. But be sure to provide them their due rights, else nobody would ever be able to save you from Allah's punishment.
There are some obligatory circumstances and some recommended circumstances.
There are three obligatory circumstances:
- The man should perform justice between wives.
- The number of current permanent wives should not be more than 4
- If the man wants to marry with the children of sister or brother of his past wife should firstly obtain the permission for new marriage from his past wife.
Some scholars add the term of having ability to financially support them.
Having justice means for example having justice in dividing spending times, living with them, paying attention and love to them.
In laws of Islamic republic of Iran (which are fully based on Jafari Fiqh) for second current permanent marriage the man should first legally obtain the permission from the Family Court by providing enough evidences for having the abilities for supporting next wife. But having more than one wife is not usual in Iran.
Finally although God permitted to have more than one wife by term of having justice among them but again God says in Quran:
And you will never be able to be equal between wives, even if you should strive [to do so]. So do not incline completely [toward one] and leave another hanging. And if you amend [your affairs] and fear Allah - then indeed, Allah is ever Forgiving and Merciful. http://tanzil.net/#4:129
Considering the latter verse it is very hard to fulfill the required term and a believer prefers to leave this heavy responsibility. but in special cases like when a large number of husbands are martyred in Jihad and so there are many alone woman remained without any husband to support then and so living with difficulties and costs and other problems, it is recommended to Muslim men marry them to they can have a living without difficulties.
Also the best role models for Muslim men are Prophet Muhammad (SAWW) and Imam Ali (a.s.) who had only one wife at a time. When Prophet (SAWW) was aged he had more than one wife that only one of them was young and others had mostly political reasons.
In normal conditions having one wife is better unless there is a special case for having more than one for example critical shortage of population of Muslims or a large number of women who their husbands are martyred in Jihad.
Allah said " If you fear you will not deal fairly with the orphans, marry if the women two, three or four." So there is obviously a condition. What does "if you fear you will not deal fairly with the orphans" mean? Cause that's only with the satisfaction of that condition that one can marry more than one woman.
The bottom line is that one can only marry a woman with orphan kids as a second, third or fourth wife.