From www.answering-christianity.com

And it just doesn't add up: Sura 4:11-12 and 4:176 state the Qur'anic inheritance law. If a man dies and leaves three daughters, his two parents and his wife then they will receive the respective shares of 2/3 for the 3 daughters together, 1/3 for the parents together [both according to verse 4:11] and 1/8 for the wife [4:12] which adds up to more than the estate available.

A second example is, that when a man leaves only his other, his wife and two sisters, then they receive 1/3 [mother, 4:11], 1/4 [wife, 4:12] and 2/3 [the two sisters, 4:176], which again adds up to 15/12 of the available property.

These verses were revealed by God to Muhammad at a time when the people of Arabia (and even many of the surrounding nations, such as the Romans, the Hindus, the Persians, etc.) gave very little heed to the rights of women. Many of them, such as the Christian Romans, would continue for many more centuries debating whether or not women even had souls. It was not until very recently that Western women actually achieved the right to inherit at all. A right which was established for them by God in the Qur'an 1400 years ago. Even such "modern" rights as pre-nuptial agreements were firmly established in Islam 1400 years before they showed up in the West. During that age, women in many of these surrounding nations were simply property of the men to be inherited with his other material belongings by his male heirs. In the Arabian peninsula, this very same attitude was held and the common law was that the male children receive the inheritance and the father receives inheritance conditional upon explicit verbal bequeathal. All others got nothing. When Islam came, God commanded Muhammad (pbuh) to return to women their fair share of the inheritance and to further establish the rights of the other relatives in the family of the deceased to receive their just share according to their relationships.

The verses dealing with inheritance are not as our current author may imagine only these couple of verses. There are many other verses in different locations throughout the Qur'an dealing with this issue. They range over the chapters of Al-Baqarah(2), Al-Nissa(4), Al-Maidah(5), Al-Anfal(8), etc. This is to say nothing about the many multiples of that in the Sunnah (Sayings of the prophet, pbuh). Out of these many verses and sayings of the prophet has been developed the science of "Al-Fara'id" which is a very vast issue and which can not be collected in a single paragraph. Suffice it to say that the question appears to display a complete unawareness of any aspects of the discipline of Al-Fara'id, its basis, its subdivisions, its special cases, the rules of "Awl" and "Usbah," the laws of "Usool" of the Fara'id, the laws of "Hajb wa Hirman," and many other issues relating to this matter. This particular example falls under the laws of "Awl" which regulate the cases when the inheritor's shares exceed or "overshoot" the sum of the total inheritance, and in which case the inheritance is recalculated according to the laws of Awl and redistributed. In the above two cases, the distribution would be "Parents: 4/27 each, wife:1/9, daughters:16/27" and for the second case, "Mother:4/15, Wife:3/15, Sisters:8/15." The books of Fiq contain specific examples of Awl, such as the Awl of Umar ibn al-Khattab, however, the interested reader can study this issue further by referring to any number of references on Islamic Fiq.

There are yet other cases when the number of inheritors and their shares do not sum to a whole 100%, in which case the laws of "Usbah" come into play in order to distribute the unclaimed shares which have no corresponding people to receive them. Then there are the laws of "Hajb wa Hirman," which encompass still other special cases of inheritance and block normally deserving relatives from inheriting in special extraordinary cases.

Our current author objects to Islamic law and wishes it to conform to his tastes. Christians officially have only one reference; the Bible. This is why he and some of his friends at times try to force this same system on Muslims. They insist that Islamic law come only from the Qur'an, thus effectively blotting out roughly one half of Islamic law.

Islamic law is based upon two references, the Qur'an (sayings of God) and the Sunnah (sayings and actions of the prophet). These two are then narrated and interpreted by the Companions through their consensus and their narrations of when and how a given verse or Hadeeth was revealed (it's context) and how the Prophet (pbuh) taught these issues to them or how he interpreted a given verse or applied it. All of this information is vital to the interpretation of a given Islamic law and none of it can be taken in a vacuum of the rest, based upon personal whims. At times the Qur'an contains a given law, at others the law is found in the Hadeeth, and in still other cases the broad outlines of a given law are presented in the Qur'an and the details are explained in the Hadeeth. For example, the Qur'an only commands Muslims to "pray." The details of how to pray are found in the Hadeeths of the prophet (pbuh) and described by the companions who saw him teach it and were themselves taught by him directly. If a non-Muslim does not like this system and rejects it then this in no way makes it any less the law of Islam or the command of God. Indeed this system itself is taught by God in the Qur'an. Examples of God commanding Muslims to obey the prophet and abide by the laws of the Sunnah and Hadeeth in interpreting the Qur'an are:

"He who obeys the messenger has indeed obeyed Allah ..." Al-Nissa(4):80

"And We (God) have sent down unto you (Muhammad) the Reminder (Qur'an), that you might make clear to mankind that which was sent down unto them and perchance they might reflect." Al-Nahil(16):44

"And We (God) have not sent down unto you (Muhammad) the Book (the Qur'an) except that you might make clear to them that in which they differ, and [as] a guidance and a mercy for a folk who believe" Al-Nahil(16):64

"And whatsoever the Messenger gives you take it, and whatsoever he forbids you, abstain [from it]. And guard yourselves from Allah, verily Allah is severe in punishment" Al-Hashr(59):7

"... And if you should differ in anything among yourselves then refer it to Allah and His messenger if you believe in Allah and in the Last Day. That is better for you and best in interpretation" Al-Nissa(4):59

etc.

A messenger of God is not simply a tape recorder that records everything that is spoken into it an then regurgitates it without explanation. Far from it. A messenger of God is a teacher whose job it is to not only pass out the textbook but to also explain the text itself, teach it, answer the student's questions regarding it, and clarify all passages wherein they find difficulty.

Similarly, the command to interpret the Qur'an and the Hadeeth only as expressly understood by the Companions due to their companionship of the prophet and their discipleship directly under his command and watchful eye can be found in quite a number of hadeeth, such as the hadeeths of "La tajtami ummati ala dhalal" and "Alaikum bi sunnati wa sunnat al-Khulafa..." among countless others.

What the "Islam bashers" do is that they take a Biblical yardstick and attempt to force it upon the Qur'an. For Christians there is only one divine reference; the Bible. In Islam there are two; the Qur'an and the Sunnah (or Hadeeth). The Qur'an can not be interpreted by Muslims based upon their personal desires. It has to be done in the light of how the prophet (pbuh) taught it. This is indeed the system which Allah commands us to follow in the above verses. Authors of such lists as this, however, prefer to take the short route of simply reading the Qur'an and then applying to it the meaning they chose, in spite of what the Prophet (pbuh) had to say in this regard and in spite of what the Companions of the Prophet (pbuh) had to say regarding the contexts of the verses, the times of their revelation, and the situations associated with each one, and the intended meanings or interpretations.