The second debate is happening here it seems:
http://www.shiachat.com/forum/topic/235030721-circular-reasoning-of-twelvers/page-2To easily refute al-Hasan's argument, he says that we refute their interpretation of the Hadith of the 12 Imams based on our "Sunni understanding" of Imamah.
He writes:
((In summary, the crux of the article's argument is that it tries to disprove the idea that the Hadith of the 12 caliphs cannot be used to refer to the 12 Aimmah of the Twelver Shi'a. The reasoning and arguments used is based on the Sunni understanding of Khilafah, that is - one of the attributes of the Khalif is to have a political role in governing affairs of the Islamic state and since all of the Imams with the exception of 'Ali did not possess this role then the Hadith cannot refer to them.))
He further writes:
((such reasoning is not objective and cannot be used since it's based on the subjective Sunni understanding of the attributes of the Khalif that is defined within Sunnism))
Truth is, this is incorrect, we refute their interpretation not using the "Sunni understanding" but rather the understanding of the Arabs at the time. For the Arabs at the time, leadership (Imamah) did not mean what the Twelvers define Imamah to be. For the Arabs, leadership had nothing to do with a certain man's progeny aside from the rest of his tribe, nor that the leader is infallible, nor that a man has to be directly connected to god so that he may lead, nor that the leader has absolute religious authority because they had priests and men of religion to take care of that aspect (Those who took care of the Ka`bah).
Arabs understood Imamah the way we understand it, they didn't understand the unique Shiite definition of Imamah, heck some tribes asked the Prophet (saw) to grant them leadership after his death and in return they'll believe in his message but he refused, in other words they had no clue about the Shiite version of Imamah.
He writes:
((Furthermore, the Khalif according to our understanding is the inheritor of the prophet's authority on religious matters and a source of guidance for the people of his time. Whether or not he gains access to political authority does not negate his position that as the prophet's Khalifah on earth and that the people can refer back to him for guidance.))
So al-Hasan's argument falls when it is clear that no Arab in Jahiliyyah shares their view, and we know that this narration was aimed at the Arabs and it addressed the Arabs of that time.
When the Prophet (saw) says that after him Islam will be fortified and strong during the rule of twelve chiefs, no Arab will understand what al-Hasan wrote above. Rather, they will think of what resembles a tribal leader.