Thus, the Imam cannot be determined or selected by the...
Thus, the Imam cannot be determined or selected by the people, since inherent knowledge and inner infallibility are unseen qualities which no one but Allah (awj) knows, and these are the two most important qualities of the Divinely-appointed Wali. A monotheist who has submitted to Divine authority over him or herself is wholly obedient to the commands and prohibitions of his or her Allah (awj).
Thus, in accepting the authority of the leaders appointed by Him as well, he or she must be fully obedient, submit to their authority, and avoid comparing them to others or baselessly second-guessing their appointment. There are several ways to recognize the divinely appointed Imam/Wali (guardian): Studying their conduct and actions. Referring to the attributes and signs that the previous Wali has mentioned for the succeeding Wali.
Seeking miracles and verifying the presence of the conditions and necessary corollaries of Imamate It is possible to find out about their lives and character by referring to books of history and biography, and by looking at collections of traditions one can find the traditions that have come down from the Prophet (ص); and finally by examining at the traditions of each Imam, one can come to recognize the next Imam.
The Imams (ع) performed miracles both in their lifetimes and after their martyrdoms. The occurrence of such extraordinary deeds for those who sought recourse to them is so frequent that it is beyond reckoning, and it is something that everyone searching for truth can experience. So there is no specific age necessary to attain the station of Imamate. The spiritual, intellectual, and mental maturity required for the position can be granted by Allah (awj) from the day of his birth.
This fact is one of the extraordinary phenomena that prove their Imamate, it does not detract from it. Obviously, from a superficial and shortsighted viewpoint, it appears difficult for prominent personalities, scholars and the old and young to submit to the authority of a boy; for ordinary people accepting such an authority would not be as easy as accepting older Wali. The contemporaries to the young Imams—that is, Imam Muhammad b.
‘Ali al-Taqi (ع) who became Imam at the age of eight, Imam ‘Ali b. Muhammad al-Naqi (ع) who attained the Imamate at the age of nine, and Imam al-Mahdi (ع) who became Imam at the age of five—were no exceptions to this rule, and they posed this very question to Imam ‘Ali b. Musa al-Rida (ع).