Al-Ashari 874 – 936

Abu al-Hasan Ali al-Ashari was an Arab Sunni theologian and the founder of the Ashari school of kalam, the dominant theological tradition of medieval Sunni Islam. After early adherence to the rationalist Mu'tazilite school, he had a famous public conversion and devoted the rest of his life to the defense of orthodox doctrine against both Mu'tazilite rationalism and the more literalist trends of his day. His Maqalat al-Islamiyyin, the Statements of the Muslims, is the earliest detailed systematic account of Islamic doctrinal differences. His school shaped the work of al-Ghazali and Fakhr al-Din al-Razi.

Abu al-Hasan al-Ash'ari was born in 874 at Basra in southern Iraq, a descendant by his own claim of the Companion of the Prophet Abu Musa al-Ash'ari. He was trained in the rationalist Mu'tazilite theology of his stepfather Abu Ali al-Jubba'i and for forty years was among its leading defenders. Around 912 he experienced a religious crisis, broke publicly with the Mu'tazila in the Friday mosque of Basra, and devoted the remainder of his life to the reformulation of Sunni theology in alignment with the doctrine of the early traditionists.

His enormous output is largely lost; the principal surviving works are Kitab al-Luma' (The Highlights), the Maqalat al-Islamiyyin (Doctrines of the Islamic Theologians) — one of the foundational works of comparative Islamic theology — the Risala fi Istihsan al-Khawd fi 'Ilm al-Kalam (Defense of the Use of Theological Reasoning), and the Ibana 'an Usul al-Diyana (Elucidation of the Foundations of Religion).

Al-Ash'ari sought a path between rigid traditionism and Mu'tazilite rationalism, accepting the literal ascriptions to God in the Qur'an and the prophetic tradition without demanding metaphorical reduction, while using rational argument to defend them. The school that bears his name became, through al-Baqillani, al-Juwayni, al-Ghazali, and Fakhr al-Din al-Razi, the dominant tradition of Sunni speculative theology. He died at Baghdad in 936.