As can be understood from the question itself, issues are of two types. One type are the issues that are ascertained through reason and are accepted through application of logical procedures and intellectual proofs, such as proving the existence of Allah, His essential attributes of perfection, and the necessity of prophecy, i.e. the proof of prophecy in general. The other type are those issues that are proved solely through narration, meaning that there is no way of proving them except revelation and relation by a truthful relater, that is, a prophet or Imam whose prophecy or Imamah is already established. Among these issues, there are also some issues that can be established in both ways. Of course, in this case the narrated proofs are a form of guidance towards the intellectual proofs. The researcher must be well attentive to this aspect of issues and must see which discussion can be established through reason, which through narration alone, and which through both methods. And in each case, he should commence according to the method peculiar to that issue so that he can reach an appropriate conclusion. Otherwise, if he wishes to enter into an exclusively narrational issue through reason, it is natural that he will not reach a valid conclusion.
It is possible that some may raise a question regarding whether the principality of reason takes precedence in the issue of Imamah over the principality of narration or not. The answer is that that in the issue of Imamah, like the issue of prophecy and the conditions of a prophet, proving the principle of general Imamah, i.e. proving the principle of a need for the existence of the Imam and the conditions of the Imam, is accomplished through reasoning. Of course, if the issue of Imamah were among the issues that are outside the limits of understanding of human reason and reasoning did not understand it independently, it could be proved by narrational evidence alone, i.e. the guidance of the Prophet. This is because reliance on narrational evidence with regard to the principle of Imamah, as opposed to the principle of prophecy, does not involve circular reasoning, though in the issue of prophecy it involves circular reasoning.
Thus, the narrational proofs of Imamah can also be regarded, similar to the narrational proofs of the principle of prophecy, as guidance to the decree of reason.
Issues such as the necessity of infallibility, how the Imam is appointed, and the fact that this affair has not been delegated to the people are principles pertaining to reason. And existing narrational proofs affirm this decree of reason. It is obvious that with groups who, like the Asha’ira, do not believe in rational good and evil, discussion can only be held through those narrational proofs. Some of the effects and benefits of the existence of the Imam and his distinctions can only be proved through narrational proofs, just as these effects and unique traits are proved for the Prophet through narrational proofs.
In the issue of the specific Imamah (the Imamah of a particular person) as well, like the specific prophecy in which explicit declaration by the previous prophet is a proof of the prophecy of the following prophet, the prophet’s declaration of the Imam’s Imamah and likewise the declaration by the previous Imam of the Imamah of the following Imam is a proof of his Imamah. There is this difference that the principle way of establishing prophecy is a miracle, since the only true way to establish the prophecy of the first prophet is through a miracle and this is the only reliable evidence of the claim of prophecy, though the prophets after his prophecy can be established both by declaration of the previous prophets and by miracle, and the Divine way has also been to send prophets along with miracles, since the establishment of prophecy through a miracle is comprehensible by all.
However, the method of declaration by the previous prophet is only an authoritative proof for believers in that previous prophet. It is for this reason that we say that the method of establishment by miracle is a general way, which is an authoritative proof for all. Still, establishing the occurrence of a miracle at the hands of a prophet is limited to narrational methods for one who is absent from the time and place of occurrence of the miracle. Certainly, the Glorious Qur’an is the only miracle whose establishment has no need of narrational proofs, since it is existent, just as the explicit declaration of the Qur’an that it is impossible to bring its like indicates that it is a miracle.
In the issue of Imamah, the Imamah of the first Imam is established solely by the Prophet’s (peace be upon him and his family) declaration, and since it has been proven in the discussion of general Imamah that the Imamah of the Imam is through specification by the Prophet by command of Allah, the miracle that is manifested by the Imam, just as it is an independent proof of the truth of claim of Imamah, is also a proof of the declaration of the prophet, if such a declaration by the Prophet (peace be upon him and his family) is not in our hands. Reliance on rational proofs in the issue of specific Imamah is in order to establish the existence of a specific declaration. For example: it can be said that it is obligatory for the prophet, in that Allah, in his absolute wisdom, has commanded the prophet to explicitly declare the Imamah, to specify and introduce the Imam after himself, even if that declaration is no longer accessible by us or has become ambiguous or its purport has become subject to doubt. Since the claim of a declaration has not been made except with regard to a specific personality – Imam ‘Ali ibn Abi Talib (peace be upon him) – rationally, the person specified by Allah and the Prophet is not other than ‘Ali ibn Abi Talib (peace be upon him).
Or it can be said that since the condition of the Imam – who is appointed by Allah and the prophet to lead humankind in religious and worldly affairs – is infallibility, and the claim of infallibility has not been made for anyone except ‘Ali ibn Abi Talib (peace be upon him), rationally ‘Ali ibn Abi Taib (peace be upon him) is the appointed and infallible Imam.
Similarly, with regard to the twelfth Imam it is said that according to narrational proofs, the world is never without an Imam and Proof (hujjat) of Allah – apparent or hidden – and in this long period of over a thousand years, the chain of Imamah is not to be severed. And since the claim of Imamah has not been forwarded for anyone other than that personage, or if it has been made its invalidity has been proved, aside from him, who is in concealment, no one else is the Imam and he is the Imam. And if he is not the Imam, other objections discussed previously in the issue of the general Imamah will once again arise. This is though there is no justification for raising them, since the result of such discussions leads to matters such as the performance of evil by Allah, the Wise, and so forth, from the like of which Allah’s essence is pure and free.