'Aql

‘Aql (Arabic: عقل‎‎, meaning "intellect"), is an Arabic language term used in Islamic philosophy or theology for the intellect or the rational faculty of the soul or mind. It is the normal translation of the Greek term nous. In jurisprudence, it is associated with using reason as a source for sharia "religious law" and has been translated as "dialectical reasoning".

While predominantly expounded by Shī‘ī and Sufi thinkers, some Sunni Muslims such as Barelvis share similar beliefs.

In Shī‘ī jurisprudence, ‘aql is the process of using intellect or logic to deduce law. Legal scholars in both Sunni and Shī‘ī Islamic traditions share Quranic interpretation, the Sunnah, and Ijma‘ "consensus" as sources of Islamic law and judicial decisions (ḥukm). However, Twelvers of the Ja‘farī school of law utilize ‘aql whereas Sunnis use qiyas "analogical reasoning" as the fourth source of law.

Among Twelvers, Akhbārīs (associated with exotericism and traditionalism and theological schools in Qom) and Usulis (associated with esotericism and rationalism and theological schools in Baghdad) were contending subschools: the former reject ijtihād outright; the latter advocate ijtihad and have been predominant for the last 300 years.

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