All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
We should know that Sharee'ah (Islamic Law) has perfect wisdom regarding all of its rulings. The Muslim individual may realize such wisdom and thus his faith increases; and he may not realize it; however, his belief in such rulings does not depend on understating the wisdom behind them. That is because he adopts the approach of complete submission to the Lord of the Worlds as Allaah The Almighty says (what means): {But no, by your Lord, they will not [truly] believe until they make you, [O Muhammad], judge concerning that over which they dispute among themselves and then find within themselves no discomfort from what you have judged and submit in [full, willing] submission.} [Quran 4:65]
To get more benefit, kindly refer to Fatwa 92206.
We do not know the wisdom behind permitting the Muslim man to have a maximum of four wives. Some people tried to probe the wisdom behind that. They have mentioned some matters as a kind of personal diligence that may be correct or incorrect. We have read that in Majallat Al-Buhooth Al-Islaamiyyah (Islamic Research Magazine) and it was attributed to some of those who are called Islamic thinkers. We will mention some of them generally in the following lines:
1- Limitation (to only four wives) may be in conformity with the four seasons of the year.
2- Limitation may be in harmony with the ratio of the number of men to the number of women.
3- All categories of women may be targeted in this way, where a man may have wives with different characteristics, i.e. the religiously committed woman, the beautiful, the wealthy, the one of high position and good lineage.
Such are some personal attempts to reach the wisdom as we have mentioned earlier. To sum up, it is sufficient wisdom for the believer to know that Allaah, the All-knowing and the All-Wise, is the One Who prescribed that.
Allaah Knows best.