The inclusion of Shari’a and absorption of all fields of life is one of its own fixed characteristics, not only through following its tenets in such fields, but also in emphasizing this fact in its general sources of derivation, too. We can find, in many such sources, texts which clearly emphasize the absorption of such Shari’a of and extension to all fields lived by man, and also of its being rich with its solutions for all problems in his path in various fields.
Observe these texts:
1) Abu Busayr, through the authority of Imam Ja’far al-Sadiq (ع), narrated saying that the Imam talked once about the inclusion and absorption of Shari’a, and the knowledge of the Family of the Prophet (ص) of all of that, saying, “It has the details of everything permissible and prohibited, and everything which people need to know, even the fine to be paid for the extremely tiny cut on one’s cheek.” Then he clasped his hands and said, “Do you permit me, O Abu Muhammed?” Abu Busayr answered, “May my life be sacrificed defending yours! I am yours to do whatever you please.” The Imam (ع) stretched his hand to the latter’s cheek, slightly pinched it then said, “Even your [facial] cut this!”
2) In Nahjul-Balagha, the Commander of the Faithful Ali ibn Abu Talib (ع), describing the Messenger of Allah (ص) and the Holy Qur’an, said: “He (the Almighty) sent him (Muhammed) after a long period of time which had lapsed since a messenger was sent, and when the nations were sleeping sound, slighting even that who had a grievance. He came to testify (in his own personal conduct) to the truth which he brought forth, the light of guidance, the Qur’an! Ask it to speak; but it will not speak to you (since you do not belong to Ahl al-Bayt); but I can tell you about it: It contains news of the future, tales of the days of yore, the remedy for your ailments and the final judgment in your disputes.”
All of these texts clearly emphasize the inclusion of the Shari’a of all aspects of life. If the Shari’a contains the solution for even the most trivial problem, such as the amount of monetary compensation to be paid by one who slightly pinches or scratches the facial tissue of another’s cheek, then it becomes necessary, according to the logic of such texts, that the Shari’a also contains the solutions for the economic problems, and a method to regulate the economic life; otherwise, how can it be called “inclusive” if it were to neglect one of the most significant and spacious aspects of life, one of its most important and complicated facets?
Can you imagine that the Shari’a, which determines the amount of compensation you should receive when someone very slightly scratches your skin, does not define your share of the produced wealth, nor does it regulate the contract between you and your employer, or with the capitalists, in various jobs which require an employee or a capitalist?
Is it conceivable that the Shari’a defines your right when you are very slightly cut while it does not do so when you bring life back to a barren land or extract a mineral or dig a well or take care of a forest?
Thus do we come to know that anyone who believes in the Shari’a and in its sources and texts is capable of deriving from such texts the solutions such Shari’a provides for the economic problems, its regulating of the economic field and, in the end, the existence of an Islamic economic system extracted from the Holy Qur’an and Sunnah.
In the light of these texts, the reader can come to know the error committed by some people who claim that the Shari’a regulates the conduct of the individual, not the society, and that the economic doctrine is a “social system”; therefore, it is beyond the limit of the Shari'a which confines itself to regulating the conduct of only the individual. The texts quoted above prove that such a claim is erroneous. These texts disclose the extension of the Shari'a to all fields of life, and that it regulates the life of both society and individual.
In fact, the claim that the Shari'a regulates the individual's conduct and not the society's is self-contradictory besides colliding with those texts because if both the individual's conduct and the regulating of this conduct are studied separately from those of the society, a grievous mistake will then be committed. The social system, which regulates the society's general aspects, be they economic or political, is embodied in the individual's own conduct; it is impossible to regulate the individual's conduct without regulating the society in which he lives.
Take a look at the capitalist system: As a social system, it regulates the economic life upon the basis of taking free economy as its principle. Such a principle is embodied within the conduct of the capitalist towards the laborer, and his way of making a work contract with him, in the conduct of the usurer with his customers whom the first lends the latter money on interest basis and in the way he conducts the interest contract with them, etc. Every social system, therefore, is linked to and directly affects the individual's conduct.
If the Shari'a regulates the individual's behavior, it, thereupon, has its own method in regulating his conduct when borrowing some money, or hiring a laborer, or working for someone else, and all of this is by necessity linked to the social system. Any separation between the conduct of the individual and that of the society in organization is certainly self-contradictory.
As long as we admit the fact that the Shari'a regulates the individual's conduct, and that it has a say in every act of man, as long as we admit all of this, we then have to carry such an admission to its conclusion and come to believe in the existence of a social system within the Shari'a.
I do not know what those who disbelieve in the existence of the Islamic economic system, or of the solutions to the economic problems in the Muslim society, say about the period of such an application during the dawn of Islam. Did not Muslims at the dawn of Islam live as a society that led an economic life and applied Islam in all its social activities? Was not the leadership of the Islamic society in the hands of the Prophet (ص) and according to the tenets of Islam?
Did not that leadership possess defined solutions in dealing with its problems of production and distribution and various other economic problems? What if we claim that these solutions express Islam's way in regulating the economic life and, then, an economic doctrine in Islam?
If we conceive the Islamic society during the government of the Prophet (ص), we cannot conceive it as lacking an economic system, because there is no society in the world without its economic system which regulates its economic life and the distribution of wealth among its members.
We cannot conceive the economic system during the period of the Prophet (ص) to be separated from Islam and from the Prophet of Islam (ص) who was the bearer of the Message and was entrusted with putting it to practice. The economic system, then, had to have been derived from his sayings, actions, or edicts; that is, it was derived from the texts of his sayings, actions, or methods in regulating the social work, since he was the Head of the State, or from his recognition and approval of a custom, or whatever. All of this stamps the economic system with its own Islamic stamp.