The proof of the second principle being the feature of the Imam; that his infallibility must be ascertained, is that we need the Imam due to our fallibility, for if the people were infallible, they would never need an Imam. They need him since they are fallible. This leads us to conclude that the reason for need of Imam is people’s fallibility. Like we say about the reason for need of an effect to its cause is its occurrence (huduth), due to the fact that an entity having huduth needs a cause, and an entity that does not have huduth, never needs a cause. So, we conclude that every effect needs a cause. Similarly, the need of every fallible to an Imam must be acknowledged, or the rule of causality will be violated.

Now, if the Imam is himself fallible, he would also be needful of an infallible Imam.

The same argument applies to his Imam, leading to the conclusion of infinite number of Imams or to an infallible Imam, which is our purpose. We have established this argument in our books, therefore, we will not prolong the inquiry by raising further questions and answering them, as the purpose of this book is different from other books and this much suffices.1

• 1. Many Shi’a scholars have reasoned through arguments of the infallibility of Ahl al-Bayt (‘a), which are extremely solid and perfect. We have also explained some of those reasons below in brief.
  A) As the respected Shaykh has mentioned in his discussion, if the Imam is not infallible, continuation would become necessary, because the appointing of the infallible Imam is obligatory since the duty-bound persons are prone to mistakes. Thus, if there is possibility of mistake in the acts of Imam as well, for removal of the mistake he would also be needful of another Imam. And if this continues and does not end with the Imam such that there should be no scope of mistake in His act, continuation would be imminent.
  B) Imam is the protector of Shari’ah, Qur’an and Sunnah and he should be infallible so there should not be any possibility of mistake from him in explaining the holy law of religion, because there is difference of opinion with regard to the meaning and interpretation of Qur’an and Sunnah and sometimes there are opposite views among scholars and commentators in the verses, which have come to us. And the Almighty Allah protects Qur’an and Sunnah through the Imam. If he is also not infallible, his interpretation would have the possibility of mistakes and errors. On the basis of this it is necessary that he should be infallible so that he explains the facts of religion law in the correct way.
  C) If the Imam is not infallible and he commits mistakes and is followed in it, in that case it is absolutely invalid. Or that he is not followed as in that case the absence of his following is absence of acceptance of his statement. Thus, the Imam has to be infallible such that his following should not become invalid and unlawful.
  D) If the appointment of the Imam is obligatory on the Almighty Allah it is just as the committing of sins would be impossible from him. On the basis of this if a sin is committed by him, mistake would be possible from him in all matters. And this is a great evil, whereas the Almighty Allah is wise and divine wisdom can never sanction it and it is an evil act. Therefore, absence of infallibility of the Imam is opposed to divine wisdom.
  E) One of the proofs of the infallibility of the Imam are the verses of the Holy Qur’an some of which are hinted at below:
  1- Surah al-Baqarah says: “My covenant does not include the unjust..." (2:124), which is a hint that the position of Imamate from the Almighty Allah is only for those who are free of every defect. On the basis of this, the holy verse negates Imamate for anyone who is sullied in sins.
  2- Surah an-Nisa’ says: “O you who believe! obey Allah and obey the Apostle and those in authority from among you” (4:59). This verse makes absolute obedience of Imam obligatory for all and has regarded it to be same as obedience of Allah. And if he is also like others, prone to mistakes, obedience to him in all matters would not be obligatory.
  3- Surah Ahzab: “Allah only desires to keep away uncleanness from you, O people of the House! and to purify you a (thorough) purifying.” (33:33). This verse says: The intention of Almighty Allah is related to the infallibility of Imam, therefore in this verse, Ahl al-Bayt (‘a) are owners of purity and every kind of impurity is negated for them. There are tens of such verses, which are explained like this in Shi’a and Sunni sources, which prove the infallibility of Ahl al-Bayt (‘a).
  F) Many traditions of the Messenger of Allah (S) also have been recorded in clarification of the infallibility of Ahl al-Bayt (‘a) from which it is possible to hint to Hadith ath-Thaqlayn that the Holy Prophet (S) said: Indeed, I am leaving among you two important things: the Book of Allah and my progeny. If you remain attached to them you will never go astray. This traditional report is quoted in many Sunni sources and all references are mentioned in Kitabullah wa Itrati fee Hadith ath-Thaqlayn min as-Sihah wa al-Sunan wa al-Masanid wa...Masadir Ahl al-Sunnah by Madressa Imam Muhammad al-Baqir (‘a) and through Hadith al-Kisa’ and many other traditional reports and verses all of which cannot be mentioned here.