Though it is widely assumed that Sunni Islam does not have an equivalent to the Christian ecclesiastical hierarchy, Shii groups such as the Medieval Ismailis did have an organised teaching, spiritual, and temporal hierarchy. Evidence gathered from primary sources shows that this Ismaili 'ecclesiastical' hierarchy is strictly intertwined with the Ismaili interpretation of Neoplatonic cosmology as well as with the political authority of prominent medieval Ismaili dynasties.
It is widely accepted by scholars in Islamic studies that there is no ecclesiastical hierarchy in Islam or, in other words, that there is not one hierarchical body which can legislate in matters of religion and the authority of which is undisputed among Muslims. There are experts in religious matters, the 'ulama`, with their theological and legal specializations. However, these are only individuals, and no matter how highly esteemed they are, they do not represent a full body. Even when Muslim scholars have presented elaborations of Islamic creeds, it is understood that they are no more than individual formulations of belief, not official ones. This assumption perpetuates a myth: the myth of one, static, uniform and united Islam. This is the Islam that many Sunnis would like to believe exists, and the Islam that several Western scholars find more convenient to study. Recent introductory books on Islam have just started to include chapters which reflect a more accurate story: there is not one Islam, there are several Islams, or to put it more moderately, there are several interpretations of Islam. There is the mystical way, with its hierarchy of spiritual masters and angels, there is popular Islam with its hierarchy of saints, and there is Shii Islam. Even though Shiism represents only 10% of the total Muslim population, it is nevertheless very active, articulated and in itself composite. This paper examines the authority of the ""ecclesiastical"" hierarchy, that is the teaching, spiritual and temporal hierarchy, in Medieval Ismailism. My aim is to establish a relationship between this hierarchy and the cosmological doctrines of Medieval Ismailism. Even though Ismailism is not the only Shi'i group in Islam to exibit both an ecclesiastical hierarchy and a related cosmological structure (medieval Druze and Nusayri groups are two further examples), it has been chosen here because of the high degree of sophistication and the clarity in which these doctrines have been expressed.