al-Qadi Abd al-Jabbar

Abd al-Jabbar ibn Ahmad al-Hamadhani al-Asadabadi was the foremost systematic theologian of the Mu'tazila, the rationalist school of Islamic kalam (speculative theology) that stressed God's absolute oneness (tawhid) and justice (adl). Born in Asadabad, near Hamadan in western Persia, around the 920s-930s — sources give the date only approximately — he studied hadith and law as a young man and travelled to Basra and then Baghdad in pursuit of learning. Biographical tradition holds that he began as an Ash'ari in theology and a Shafi'i in law before embracing Mu'tazili doctrine. In Baghdad he attached himself to the Mu'tazili master Abu Abd Allah al-Basri, becoming the leading exponent of the Bahshamiyya, the branch of the school named after Abu Hashim al-Jubba'i. In law he followed the Shafi'i madhhab (school of jurisprudence).

In 367/978 the Buyid vizier al-Sahib ibn Abbad, a committed patron of the Mu'tazila, summoned him to Rayy and made him chief judge (qadi al-qudat) of the province, the title by which he is remembered. After his patron's death he was reportedly deposed and arrested by the Buyid ruler Fakhr al-Dawla over a remark about the late vizier; he then devoted himself to teaching. He died at Rayy in 415/1025. His twenty-volume al-Mughni is the most complete Mu'tazili summa to survive, recovered largely in the twentieth century from a Yemeni Zaydi manuscript. Whether Mu'tazili kalam is sound doctrine was contested then and later by Ash'ari and other theologians; this entry records his positions, not their truth.