Early practitioners stressed the supremacy of human reason and free-will (similar to Qadariyya) and went on to develop an epistemology, ontology and psychology which provide a basis for explaining the nature of the world, God, man and religion.
In Judaism (Rabbanite and Karaite) Bahshamiyya Mu'tazila was adopted in Sura and Pumbeditha Academies of Babylon, in varying degrees, from the 9th century onwards.
The influence of Bahshamiyya Mu'tazila quickly became central to Jewish religious and intellectual life in the East - slowly migrating across North Africa with the Fatmimids and making it way to al-Andalus.
The rationalistic approach of Mu'tazila towards reasoned theological issues led to the classification of Mu'tazilîs as freethinkers within Islam who had been deeply influenced by Greek philosophical thought and thus practiced apostasy and heresy.
A similar attitude was assumed by Tosafists and Kabbalists towards "Jewish Kalam" In the 1950s a number of manuscripts were discovered in the library of the Great Mosque in Sana'a, Yemen.
These contained texts by Abû Hâshim al-Jubbâ'î, the Bahshamiyya; they also included 14 of 20 volumes of the encyclopedic Kitâb al-Mughnî fî abwâb al-tawhîd wa-l-'adl of Abd al-Jabbâr al-Hamadhânî.
Further writings by followers of the Bahshamiyya School that were found included Ta'lîq sharh al-usûl al-khamsa, a recension of the Sharh usûl al-khamsa of Abd al-Jabbâr by one of his followers, Mânakdîm, as well as al-Kitâb al-Majmû' fî l-muhît bi-l-taklîf, a recension of Abd al-Jabbâr's al-Kitâb al-Muhît bi-l-taklîf by Ibn Mattawayh.
However, no texts prior to Abd al-Jabbâr were discovered; the same applies to rival groups to the Bahshamiyya such as the Ikhshîdiyya, or the school of Baghdad, whose doctrines were to a large extent formulated by Abû l-Qâsim al-Ka'bî al-Balkhî.
Indigenous North African Fatimids who were good enough to be recruited and die as soldiers yet excluded from Arab culture and society due to their skin-color.
Abd al-Jabbar harmonized some of the Mu'tazili 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).