According to the Qur'ān, husbands are the guardians of their wives. Why is that so? Why should they head a family?
Men and women are the two building blocks of the smallest unit of the society: the family. The Almighty has made them such that they complement one another. In other words, they are not duplicates of one another; they are different from each other. By complement is meant that they complete certain voids present in each other. This also is precisely why they need one another to form a family. The Qur’ān says that for a healthy society, both sexes should acknowledge each other's inborn qualities and characteristics and not become jealous:
And in no way covet those things in which Allah has bestowed you His gifts more freely on some of you than on others: Men shall be given a share from what they earn and women shall be given a share from what they earn, and ask Allah of His bounty. For Allah has full knowledge of all things. (4:32)
In other words, what the Qur’ān is implying here is that the real sphere of competition is not natural abilities for they have been bestowed by the Almighty; it is the sphere in which one uses these abilities to earn for one’s self some reward in the Hereafter in which men and women should strive and compete with each other.
After spelling out the correct attitude in this regard, the Qur’ān, goes on to say:
Men are the guardians of women because Allah has given one superiority over the other and because they [--- men ---] support them from their means. (4:34)
According to this verse, men are more suited to head a family because of the fact that they are physically and temperamentally more suited. This suitability has been ingrained in their nature by the Almighty. Their physical strength and mental disposition make them more appropriate of the two to carry out this responsibility. The word qawwām (guardian) combines in it the concepts of physical protection and moral responsibility.
The second reason pointed out by this verse for this choice is that on a man lies the responsibility of earning for his wife and children. It is but natural for one who financially maintains and looks after the individuals entrusted to him to be at the helm of their affairs. In this regard, however, it must remain clear that Islam does not forbid women to earn a living. It has only freed them from the responsibility of earning, which lies upon men. It also needs to be understood that the verse does not say that the one among the husband or wife who supports the family should become the head;. husbands, whether their wives earn or not, are liable for this responsibility. A women may earn if she likes or if some need arises, but since she has not been entrusted with this duty she has not been given the governing position in the family.
The verse, it should remain in consideration, very clearly states that men's superiority to women is not absolute; it is only relative and confined to certain spheres. Consequently, there are certain spheres in which women by nature -- physical, physiological as well as psychological -- are far superior to men and much more suitable to do certain tasks.