'Abd al-Jabbar was a Mu'tazilite theologian and Shafi'ite jurist, known as Qadi 'Abd al-Jabbar b. Ahmad al-Hamadani. He was born in Asadabad in Iran about 935, studied kalam with Abu Ishaq al-'Ayyash in Basra, and associated with the prominent Mu'tazilite scholar Abu 'Abdullah al-Basri in Baghdad. 'Abd al-Jabbar was appointed as chiefjudge of Rayy with a great authority over other regions in northern Iran by the Buyid wazir Sahib b. 'Abbad in 977. Following his dismissal from the post after the death of Ibn 'Abbad, he devoted his life to teaching. In 999 he made a pilgrimage to Mecca through Baghdad, where he spent some time. He taught briefly in Kazvin (1018-1019) and died in 1025 in Ray.
As the teacher of the well-known Mu'tazilites of the eleventh century, such as Abu Rashid al-Nisaburi, Ibn Mattawayh, Abu 'l-Husayn al-Basri, and as the master of Mu'tazilism in its late period, 'Abd al-Jabbar elaborated and expanded the teachings of Bahshamiyya, the subgroup named after Abu Hashim al-Jubba'i. He synthesized some of the Mu'tazilite views with Sunni doctrine on the relation of reason and revelation, and came close to the Shi'ite position on the question of leadership (imama). He is also a significant source of information on ancient Iranian and other monotheistic religions.
'Abd al-Jabbar wrote many works on kalam, especially on the defense of the Qur'an, and on the Prophet of Islam. Some of his books, including most of his twenty-volume work al-Mughni, have been published. Commentaries on two of his lost books, Sharh al-usul al-khamsa by Qiwam al-Din Mankdim and al-Muhit bi'l-taklif by Ibn Mattawayh, are also available.