Abà « Sahl Bishr ibn al-Muÿtamir ibn Bishr al-ḤilÃÂlë (died 825) was a MuÿtaziliteâÂÂZaydite theologian and founder of the Bishriyya school in Baghdad.
The place of Bishr's birth is unknown. Baghdad, Kà «fa and Baá¹£ra have all been proposed. Likewise, the date of his birth is unknown, although he was an old man at his death. He studied Muÿtazilite (theology) in Baá¹£ra under Bishr ibn Saÿëd, Abà « ÿUthmÃÂn al-ZaÿfarÃÂnë and Muÿammar ibn ÿAbbÃÂd al-Sulamë. He later moved to Baghdad to teach. Among his most prominent students were ThumÃÂma ibn Ashras and Abà « Mà «sàal-MurdÃÂr.
In Baghdad, Bishr worked as a slave trader. He was an ardent Zaydite missionary, who once promised to convert two people per day, and a staunch advocate of jihad, who financed individual warriors. Caliph HÃÂrà «n al-Rashëd (), an opponent of Muÿtazilism, imprisoned Bishr for his alleged RÃÂfiá¸Âë sympathies. Bishr denied the charge. In prison, he wrote 40,000 verses on justice, monotheism and the threat of judgement. They circulated widely and increased his influence, so the caliph released him. He was a friend of the caliph's vizier, Faá¸Âl ibn YaḥyÃÂ. He later joined the court of the Caliph al-Maþmà «n in Merv. According to al-Qalqashandë, Bishr was a signatory of the 817 decree of the caliph that named ÿAlë al-Riá¸Âàas his successor.
Ibn al-Nadëm attributes 24 titles to Bishr, mostly polemical works. Another 25 titles are cited by other authors. Many of his theological works were in verse. Only two long poems (qaṣëdas) on the wonders of creation, including the lives of insects, are preserved in al-JÃÂḥiáºÂ's ḤayawÃÂn. The rest are known only from fragments quoted in other Muÿtazilite works, like al-KhayyÃÂá¹Â's KitÃÂb al-Intiá¹£ÃÂr. He wrote treatises criticizing his Muÿtazilite colleagues, such as Abà « l-Hudhayl, and made attempted refutations of Christianity, Judaism, Kharijism and Zoroastrianism. He wrote, in verse, one of the earliest works intending to prove Muḥammad's prophethood. One of the works Ibn al-Nadëm ascribes to him is a versification of Kalëla wa-Dimna.
Bishr is best known for his concept of the 'engendered act' (tawallud), which refers to the effects engendered or caused by an act of the human will but that are not themselves directly willed. He held humans morally responsible for the effects brought about by their will. He held that the human will was independent of God, which led to accusations of unbelief, although his primary motivation appears to have been to avoid accusing God of evil.
Bishr subscribed to the Zaydite view of the imamate. He regarded ÿAlë as superior among the companions of Muḥammad and accepted his legitimacy, but distinguished superiority from right of succession. He rejected the legitimacy of the last six years of ÿUthmÃÂn's caliphate. Politically, he was a Shëÿë. He regarded the KhawÃÂrij as rebels.