The issue of the features of the Prophet’s successor, of how to choose him, of whether sovereignty of an inferior (Mafzūl) person in human society is legitimized while there is a superior (Afzal) one or not are among the issues which has led to the split of the Muslims into different sects. Regarding this, the Mu'tazilah has turned into an in-depth dialogue. In the present article, the author has tried to discuss the question of Imamate who rules the society from Mu'tazilah’s point of view, and following this, he is going to speak about Baghdādis’ idea. In this regard, he, first of all, studies the historicalevolution oftheMu'tazilahschooland then discussesMu'tazilah’s approach to the issue of Imamate. The author continues with presenting the issue of whether the superior (Afzal) option should take the priority or the better (Fāzel) one; and states that the necessity of Imamate is necessary, or the permission of a better (Fāzel) Imamate is one of the most important subjects of theologians’ thought. Then he, accepting the necessity of a better (Fāzel) Imamate, goes to the othertheologians’ questionaboutwho isthebest ofUmma (nation)afterthe Prophet and talks about the instance of the best (afzal) after the Prophet. The other topics which are being discussed in the present article are as following: pointing out the reasons of the superiority of Imam from Iskāfi’s point of view, believing in the superiority (TafzÐl) of the ruler among the recent scholars of Basreh, and finally mentioning IbnHadid as one of the I’tezāli’s character.