"The authority of reason forms the foundation of Islamic theological and legal thought.

Until recently, most Western academics wrongly looked upon the Mu'tazili school of theology as the sole example of Islamic rationalism. In reality, its rivals, the Ash'ari and Maturidi schools, which make up the mainstream of Sunni orthodoxy, are no less rationalistic, and their speculations consistently demonstrate originality and intellectual depth. [12] Pragmatic reason is central to the Islamic legal tradition. Even the Hanbali school of law, which is known for textual literalism, is highly pragmatic and cedes a significant role to reason in both theology and law. In fact, the school was divided from an early period between two wings, one of which relied more heavily on reason than the other. Ibn Taymiyya, one of the greatest Hanbali scholars, and his disciple Ibn al-Qayyim belonged to the school's rationalist wing. Another school of law, the extremely literalist Zahiris rejected the use of reason in theology and law but never won a significant following; they died out early, in part, because of their rejection of reason.

-See "Trusting Reason" in Dr. Umar F. Abd-Allah's important article "Living Islam With Purpose," p. 4