Personality and Characteristics of the Holy Imams (A.S.)
Generally speaking, an Imam enjoys a unique personality and distinctive characteristics, in as far as Shi'a followers of the Imams are concerned; therefore, he is not permitted to do what others are, such as falling into error, or getting confused about a matter. Rather, infallibility is essential in him since he conveys on behalf of the Prophet (S.A.W.) what seems to others to be obscure of the Message and its intricacies. Just as we proved the infallibility of the Prophet (S.A.W.), we, by the same token, prove infallibility for the Imam as well with one exception: the Imam conveys on behalf of the Prophet (S.A.W.), whereas the Prophet conveys on behalf of the Almighty God. The wisdom in this argument is that should falling into error be accepted and expected from the Prophet (S.A.W.) or the Imam, then doubt will result regarding the reliability of what they convey to people of juristic rules and regulations and other such matters since they are liable to err in their judgement or get confused about a particular issue.
Although the believers are not held accountable for doing what they are not supposed to be doing due to such error of judgement, the assumption of the error of judgement itself collides with the very wisdom behind the reason why prophets were sent to people at all which is to clarify to people, according to the way God Almighty intended them to, without any error or confusion, what His Will is.
The topic of infallibility is a vast one the discussion of which has no room here and which requires a dedicated research I may be able one day to tackle. What I have to same here is that Imamate is characterized by certain distinctive aspects such as infallibility which we cannot discuss by itself with others except after both parties agree on the basis from which it emerged; otherwise, our case would be like one who discusses the necessity of performing the ritual prayers (salat) with someone who does not believe in the message of the Prophet (S.A.W.).
The basic point upon which we have first and foremost to agree is the definition of general Imamate, then the distinctions it requires and, finally, the proofs which testify to these distinctions. It is only then that disagreeing parties can conduct a reasonable discussion. Having been convinced by unequivocal proofs of such infallibility, and having seen the Twelve Imams (A.S.) to be fully qualified to be the only ones in whom such infallibility could be observed, we became fully convinced of their unshakable superiority over all others, and that they were the ones adorned with absolute human perfection.
An Imam, according to this viewpoint, has got to be the most learned among people and the most aware of the general needs of people such as knowledge or other necessities of life, and that he has to be the most pious, the most ascetic, the most perfect in personal conduct and norms of behaviour. In other words, in order to be qualified for Imamate, one has to be superior to everyone else in all aspects of perfection and its requirements which all raise him to his position of leadership.