It is apparent that the least they can say is that they were...
It is apparent that the least they can say is that they were not infallible (theoratically) but were protected from sins and errors (practically). But infallibility is not enough. According to our belief, as the Prophets were chosen by Allah to carry on His mission, so their successors also should be appointed by Allah. It may be mentioned here that there are some more conditions for Imamah, but I have mentioned here two of them only i.e.
Infallibility and appointment by Allah through the Prophet, because these two conditions are the most important of all. Now I think I should throw some light on the question of our Imams' appointment by Allah.
As I have mentioned earlier Prophet made a promise to `Ali (which was in fact a command of Allah) in the early days of Islam that he would be his successor, and that promise was fulfilled in Khumm when the Prophet declared that all the believers were to accept `Ali as their Master just as they accepted the Prophet as their Master. `Ali was the man who was chosen by the Prophet to sleep in his bed and offer himself for sacrifice when the Prophet left Mecca.
He was entrusted to return the articles of the Meccans that were deposited with Muhammad (S). `Ali was the man whom the Prophet declared twice as his brother in this world and the life hereafter. It was `Ali, his wife and his children who were selected by the Prophet to represent Islam against the tribe of Najran.
It was about `Ali that the Prophet said: "I am the city of knowledge and `Ali is its gate." It was the famous saying of the Prophet that: "`Ali is from me and I am from `Ali." It was to `Ali that the Prophet said: "Thou hast the same position with me as Aaron had with Moses." Thus it is clear that so far as `Ali is concerned the question of infallibility and appointment from Allah are settled once and forever.
Even the Sunnis do not challenge the authenticity of these traditions and events, although they might differ in interpretations. After the death of the Prophet the Muslims split in two groups; Sunnis and Shi`ahs. The Shi'ahs, as mentioned above believe that `Ali was the first Imam appointed by Allah, declared by the Prophet. The Sunnis believe that Abu Bakr, a father-in-law of the Prophet, was his first successor.
They call them "Caliphs." Abu Bakr was elected by some people at the time when most of the Muslims were attending the funeral of the Prophet.