Man's primordial nature does not doubt the importance and...
Man's primordial nature does not doubt the importance and value of the fact that the creation of a society depends on a set of common regulations and customs which are accepted in practice by the majority of the groups in that society, and that the existence and continuation of that society depend upon a just government which agrees to carry out these regulations completely. Any one who possesses intelligence does not neglect of forget this fact.
At the same time one can doubt neither the breadth and detailed nature of the Islamic Shari'ah, nor the importance and value the Prophet considered it to possess, so that he made many sacrifices for its application and preservation. Nor can one debate about the mental genius, perfection of intelligence, perspicacity of vision or power of deliberation of the Prophet (beside the fact that this is affirmed through revelation and prophecy).
According to established traditions in both Sunni and Shi'ite collections of hadith (in the chapter on temptations and seditions and others) transmitted from the Prophet, the Prophet foretold seditions and tribulations which would entangle Islamic society after his death, and the forms of corruption which would penetrate the body of Islam, and later worldly rulers who would sacrifice this pure religion for their own impure, unscrupulous ends.
How is it possible that the Prophet should not neglect to speak of the details of events and trials of years or even thousands of years after him, and yet would neglect the condition that had to be brought into being most urgently after his death? Or that he should be negligent and consider as unimportant a duty that is on the one hand simple and evident and on the other significant to such a degree?
How could he concern himself with the most natural and common acts such as eating, drinking and sleeping and give hundreds of commands concerning them, yet remain completely silent about this important problem and not appoint someone in his own place?
Even if we accepted the hypothesis (which Shi'ism does not accept) that the appointment of the ruler of Islamic society is given by the Shari'ah to the people themselves, still it would be necessary for the Prophet to give an explanation concerning this matter. He would have had to give the necessary instructions to the community so that they would be aware of the problem upon which the existence and growth of Islamic society and the life of religious symbols and observances depended and relied.