A well-known historical narrative links the name Muʿtazilah to Wāṣil ibn ʿAṭāʾ and his divergence from a circle associated with al-Ḥasan al-Baṣrī. The issue was how to classify a Muslim who commits a grave sin, and the narrative associates Wāṣil's distinct position with the term *iʿtizāl* (“withdrawal”).
The naming narrative should be distinguished from the school's actual doctrinal propositions. It is a traditional account of the name, not a sufficient account of the full historical emergence and development of Muʿtazilite thought.
The central doctrinal question was whether a person who professes faith but commits a grave sin is described as a believer, an unbeliever, or assigned an intermediate category. Different theological schools developed different answers to that classification.