The Mu‘tazila was a current of thought that flourished in Iraq in the third/ninth century, but whose creative influences continued at least into the twelfth century. It had a fundamental role in Islamic history and thought, particularly in the early period when it became the state theology under the ‘Abbasid caliph al-Ma’mun. The Mu‘tazila developed a type of rationalism, partly influenced by Greek philosophy, based around three fundamental principles: the oneness and justice of God, human freedom of action and the creation of the Qur’an. During the history of Islamic thought, these ideas were challenged and then abandoned in the name of an orthodoxy that found expression particularly in Ash‘arism. Despite this crisis, the Mu‘tazila survived in Islamic thought, most importantly in relation to Shi‘ite theology. In modern times it has seen a revival, at a moment when the evolution of Islamic history has been obliged to confront the modern world. Many contemporary Islamic thinkers have looked to the rationalism of the Mu‘tazila and its principles in an attempt to give new life to Islamic thought, seeking to equip it to face the challenges of history.