CALIPH AND CALIPHATE. - The Arabic title halifah means "successor," "lieutenant," and appears frequently also in the Qur'an, but never in the technical sense it later acquired, of lieutenant of the prophet (halifat rasūl Allāh). This title seems to have been assumed for the first time by the caliph 'Omar, and from then on "caliph" meant the head of the Muslim theocratic state; it is therefore in no way parallel to the Catholic title of "pope," and it would be erroneous to consider the caliph as the "pope of the Muslims."
After the death of the prophet (632) the leadership of the Muslim community passed to Abū Bakr (632-34), then to 'Omar (634-44), 'Otmān (644-56), 'Alī (656-61). These are the four so-called "orthodox" caliphs (ra'īddin). From the political-religious struggles that followed the assassination of the caliph 'Otmān and the caliphate of 'Alī was born the Šī'ah, which divided and still divides the Muslim world: the Shiites recognize 'Alī and his descendants as the only legitimate caliphs or imām.
This hereditary principle, contrary to pure Arab-Bedouin traditions, nevertheless took hold also among non-Shiites, and the four "orthodox" caliphs were followed by the Umayyad dynasty (661-750), bitter enemies of the partisans of 'Alī. So strong, however, was the Arab "democratic" tradition that the caliph who came to power had to receive a formal ba'ah (official recognition) from the Muslim communities. Under the Umayyads the capital of the Arab-Muslim empire was moved from Medina to Damascus: the Umayyads especially emphasized the political side of their functions.
The Umayyad dynasty was followed by that of the 'Abbāsids (750-1258), which moved the capital to Baghdad. With the coming to power of the 'Abbāsids (who obtained the throne also with the help of the Shiites, whom they then began to persecute), Persian monarchical traditions prevailed over the democratic Bedouin simplicity of the "orthodox" caliphs and of the early Umayyads, when the caliph was still a "primus inter pares." At the same time the 'Abbāsid caliphs gave greater importance to the religious side of their office, donned the mantle of the Prophet and displayed ties of kinship with the family of Muhammad. During the reign of the 'Abbāsids various more or less independent Muslim princes began to form, and already by around 946 no effective political power remained in the hands of the caliph of Baghdad, although he was still considered by theorists, mindful of ancient greatness, as the source of all authority in the Muslim world. Caliphates rival to that of Baghdad did, however, form, the most important of which were the Umayyad caliphate of Spain (the title of caliph was assumed by 'Abdarrahmān III in 928) and the Shiite one of the Fātimids of Egypt (909-1171). When Hūlāgū, grandson of Genghis Khan, occupied and devastated Baghdad, killing the last 'Abbāsid caliph Musta'ṣim (1258), for the first time the Muslim world lacked a head.
The descendants of the 'Abbāsid caliphs who held the office of caliph for many long years still at Cairo (1261-1517) were nothing but puppets in the hands of the Mamluk sultans of Egypt and had no power, being ignored by the majority of Muslims. When the Ottoman sultan Selim made his triumphal entry into Cairo (1517) and transported Mutawakkil, the last shadow of an 'Abbāsid caliph, to Constantinople, he had already assumed for himself the title of caliph, a title which it was then sought to legitimize (according to Sunni doctrine the caliph must belong to the family of the Quraysh) with the legend of a supposed investiture of Selim by Mutawakkil.
From then on the powers of the caliphate were held by the Ottoman sultans until 1922, when, the sultanate having been abolished, the caliphate was artificially maintained as a simple religious office, which was also abolished in 1924.
As stated above, the caliph can in no way be compared, as regards his functions, to a "pope." The office of the caliph is purely that of holding together and politically governing that religious community which alone has the right to decide (through its learned men, 'ulemā', muftis, etc.) on religious questions not already decided by the Qur'an and the sunnah (v.). The caliph is a believer like any other and has no legislative power in religious matters. If, moreover, one considers that according to orthodox theory the caliphate must belong, as has been said, to the family of the Quraysh, one may conclude that the caliphate in its legitimate form in reality ceased to exist in 1258, with the fall of Baghdad, and that the Muslim world has for several centuries been unaccustomed to being governed by a caliph.
As for the Shiite idea of the caliph, it should be noted how the concept of imām (v.) is fundamental in the B'ah. The caliph or imām has superhuman qualities, and the imamate is restricted not only to the tribe of the Quraysh but to the family of 'Alī: the Shiites in fact, with few exceptions, reject the concept of the electivity of the caliph and affirm that the superhuman qualities of 'Alī are hereditary in all his successors.
According to the ultra-democratic concepts of the ḥāriǧites (v.), on the other hand, the caliphate is not indispensable (the functions of the caliph can be exercised by the community) and any believer can be elected caliph.