Power, Reversal, and What Survived

The fortunes of the school turned on a caliph. Al-Mamun adopted the doctrine of the created Quran and in 833 imposed it as a test on judges and scholars, an episode known as the mihna. His two successors continued it and al-Mutawakkil abandoned it around 848. That reversal is why Mutazilism is remembered in Sunni Islam as a defeated position, and it handed its opponents a durable argument as well, since a theology that had reached for the machinery of the state to settle a question could afterwards be presented as having lost the argument on its merits.

What followed was not disappearance. Mutazili positions were adopted almost entire by Zaydi Shia theology in Yemen and substantially by Twelver Shia theology, where the insistence on divine justice and on reason having access to moral truth is still standard. The Ashari and Maturidi schools that displaced the Mutazila in Sunni Islam were built specifically to answer them, and they kept the vocabulary and much of the method of argument even where they rejected the conclusions.

Most of what is known about the school from its own side, rather than through the reports of the people who refuted it, comes from manuscripts preserved in Zaydi libraries in Yemen. The recovery in the twentieth century of the greater part of the Mughni of Abd al-Jabbar, a systematic work running to many volumes, changed the field considerably, because until then a school that had argued for the sufficiency of reason was being read almost entirely through summaries written by its opponents.