Usul al‑Madhhab (Doctrines Particular to Sects)
1. There is no question as to the necessity of appointment of the Imam, leader or ruler of an Islamic society. The point of difference, however, is that the Ash'arites say that the appointment of the Imam is an obligation of the people themselves, and base their argument on quoted traditional evidence (adillah naqliyyah).
The Mu'tazilites and the Zaydiyyah, too, consider the appointment of the Imam the duty of the people, but base their argument on rational reasons (adillah ‘aqliyyah).
The lmamiyyah Shiites, in accordance with the belief in Divine Grace (al‑Lutf), believe the appointment of the Imam to be incumbent upon God.