According to the Old Testament, King Solomon had 200+ wives.....and still loved by God (his and ours). Same as with Abraham (father of Christianity, Judaism, and Islam).....who had several wives. hehehe.
God said, "Increase and multiply". He did not say, "Decrease and divide".
He designed man to propagate. To ensure the continuity of the human race at all cost. Therefore, the more wives he has, the more offspring he breeds. In fact, theoretically, he can breed an entire herd. Hence, polygamy is a biological imperative for him.
Note that this does not hold true with the woman. It doesn't mean that the more husbands she has, the more children she will have. Hence, polyandry is not a biological imperative for her.
Another thing. Paramount consideration is on best interests of the child. As such, child has every right to be able to identify real father. How's this possible if mom is a swinger? Who's gonna father the child? Provide child support? etc?
Isn’t this, then, the law of nature. What mother nature intends?
Isn't the Islamic law on marriage the law that should be adhered to, then?