One question raised about Islam is that why the blood money of a woman is half of that of a man. The answer is that the duty of providing the fanancial needs of the family lies with the man. Therefor, the absence of man will bring about a greater financial loss to the family. Islam has regulated the blood money of a man to be twice of that of a woman to meet the financial needs of the family.
According to jurisprudential and historical studies, blood money is an economical matter. It has been legislated in order to compensate for the loss incurred by the injured. From another point of view, in an ideal society, which Islam attempts to create, most of the economic activity is carried out by men. When we look at the general economic responsibilities of men we find that men have duties that women have been excused from. While the most important responsibility of a woman, but not the only one, is to manage the cornerstone of society, in other words the family, the most important duty of man, but not the only one, is to provide for the economic needs of the family.
When we pay attention to this matter we can easily conclude that Islam must strengthen those matters that have financial consequences for men and amongst these matters is blood money. Men play a pivotal role in the economic life of the family. From another point of view, blood money is related to the physical aspect of the human being. Hence, if someone’s body were stronger his blood money would be more. Since men are more productive economically than women, their blood money is more than that of women. This does not mean of course that in Islam the position and status of a woman is less than that of a man. If blood money was related to the worth and position of individuals, then the blood money of a scholar or the leader of society would not be equal to that of an average worker.
Another important point pertains to the role a man plays in the security of his household. It is very clear that it is the man that protects the family. This would imply that the loss inflicted on a family if the man was not present would be far greater than if the woman was not there. In the end it is necessary to keep this in mind that in every case the laws that have been presented by a religion or school of thought are always in line with the principles that that religion or school of thought has formed in regards to that matter. It is in accordance to the sum total of those viewpoints that the law has been passed. In regards to blood money as well, Islam has formed its law while taking into consideration the responsibilities and rights of both men and women and the general laws that pertain to the family system. We cannot therefore look at them separately and subjectively.
Source: http://www.islamquest.net/en/archive/question/fa2379