The Muʿtazila was a rationalist school of Islamic theology and one of the important currents of Islamic thought. Muʿtazilīs stressed the primacy of reason and free will and maintained that good and evil can be known solely through human reason. The beginnings of the Muʿtazila were in the 8th century, and their classic period of development was from the 9th until the middle of the 11th century. While it briefly enjoyed the status of an official theology, over the centuries the Muʿtazila fell out of favour in Sunnī Islam and had largely disappeared by the 14th century. Their influence, however, continued to be felt in two groups: Shīʿī Islam and Karaite Judaism. There has been a trend in the 20th century to revive Muʿtazilī thought, particularly in Egypt. The Neo-Muʿtazilīs are attracted by the Muʿtazilī affirmation of reason and free will, which they see as a basis for intellectual liberty and modernity. Muʿtazilī thought also had a major impact on Jewish theologians, both Rabbanite and Karaite, from the 10th through the 12th centuries.

Muʿtazilī works were evidently not widely copied, and few manuscripts have survived. So little authentic Muʿtazilī literature was available that until the publication of some texts in the 1960s, Muʿtazilī doctrine was known mostly through the works of its opponents. While Muʿtazilī manuscripts have not been preserved in large quantities, most of the material that has survived has not yet been utilized or published. Muʿtazilī manuscripts have survived largely by two means: Yeminite public and private libraries, and the Firkovitch Collections in the Russian National Library in St. Petersburg, which came mostly from the manuscript storeroom of the Karaite synagogue in Cairo. In the early 1950s numerous manuscripts were discovered in Yemen that included the works of various representatives of the Muʿtazilī school of Abū Hāshim al-Jubbāʾī (d.933), the Bahshamiyya, which were subequently edited in Egypt during the 1960s.

The goal of our study group is to examine, identify and edit as many as possible of the Muʿtazilī writings and fragments scattered in the various Muslim and Jewish repositories around the world, in order to broaden our understanding of rational theology in Islam and its reception among Rabbanite and particularly Karaite Jews.