Mu'tazili in the context of "The People of Monotheism"

Ahmad ibn Hanbal (Arabic: أحمد ابن حنبل, romanized: Aḥmad ibn Ḥanbal; (164-241 AH; 780 – 855 CE) was an Arab jurist and founder of the Hanbali school who is widely recognized as the scholar who memorized the most Hadiths in Islamic history. One of the most venerated Islamic intellectual figures, ibn Hanbal is notable for his unmatched memorization of over one million prophetic narrations, an unprecedented number that has never been claimed by any other muhaddith. Ibn Hanbal also compiled the largest hadith collection, al-Musnad, which has continued to exercise considerable influence on the field of hadith studies up to the present time, shaping the methodological framework later employed in both Sahih Bukhari and Sahih Muslim. Imam al-Dhahabi described him as “the true Imam, the proof of the religion, the master of hadith, and the leader of the Sunnah”. Imam Ali ibn al-Madini said: “Truly, Allah supported this religion through two men, to whom there is no third: Abu Bakr during the Ridda Wars, and Ahmad ibn Hanbal during the Mihna”.

Having studied jurisprudence and hadith under many teachers during his youth, Ibn Hanbal became famous in his later life for the crucial role he played in the Mihna instituted by the Abbasid caliph al-Ma'mun toward the end of his reign, in which the ruler gave official state support to the Mu'tazili doctrine of the Quran being created, a view that contradicted the orthodox position of the Quran being the eternal, uncreated word of God. Living in poverty throughout his lifetime working as a baker, and suffering physical persecution under the caliphs for his unflinching adherence to the traditional doctrine, Ibn Hanbal's fortitude in this particular event only bolstered his "resounding reputation" in the annals of Sunni history.

Qadariyyah (Arabic: قَدَرِيَّة, romanized: Qadariyya), also Qadarites or Kadarites, from qadar (قدر), meaning "power", was originally a derogatory term designating early Islamic theologians who rejected the concept of predestination in Islam, qadr, and asserted that humans possess absolute free will, making them responsible for their actions, justifying divine punishment and absolving God of responsibility for evil in the world. Originally, the Qadarites also reject belief in the prior knowledge of God, and they deny that God wrote the decrees concerning His creation before He created the heavens and the earth; Consequently, their belief goes against the teachings of Sunni Islam. Some of their doctrines were later adopted by the Mu'tazilis and rejected by the Ash'aris. They argued that evil actions of human beings could not be decreed by God, as they would have to be if there was no free will and all events in the universe were determined by God.

Qadariyyah was one of the first philosophical schools in Islam. The earliest document associated with the movement is the pseudoepigraphical text Risala attributed to Hasan al-Basri, which was composed between 75 AH/694 CE and 80/699, though debates about free will in Islam probably predate this text. According to Sunni sources, the Qadariyah were censured by Muhammad himself by being compared to Zoroastrians, who likewise deny predestination.

Early Islamic law placed importance on formulating standards of argument, which gave rise to a "novel approach to logic" (Arabic: منطق manṭiq "speech, eloquence") in Kalam (Islamic scholasticism).However, with the rise of the Mu'tazili philosophers, who highly valued Aristotle's Organon, this approach was displaced by the older ideas from Hellenistic philosophy. The works of al-Farabi, Avicenna, al-Ghazali and other Muslim logicians who often criticized and corrected Aristotelian logic and introduced their own forms of logic, also played a central role in the subsequent development of European logic during the Renaissance. Scholars who have studied Islamic logic include Nicholas Rescher, who in a 1964 work contextualized some 170 Arabic-language logicians, without the book being exhaustive. There have been hundreds of original treatises in the subject as well thousands of later commentaries or supra-commentaries.

According to the Routledge Encyclopedia of Philosophy:

Al-Kashshaaf 'an Haqa'iq at-Tanzil, popularly known as Al-Kashshaaf (Arabic: ٱلْكَشَّاف, romanized: al-Kaššāf, lit. 'the Revealer') is a seminal tafsir (commentary on the Qur'an) by Al-Zamakhshari written in the 12th century. Considered a primary source by major scholars, it is famous for its deep linguistic analysis, demonstrations of the supremacy of declamation of the Qur'an, and the representation of the method the Qur'an uses to convey meaning using literary elements and figurative speech. However, it is criticized for the inclusion of Muʿtazilah philosophical views.