Against them, the more parochial scholars who took pride in believing "bila kayfa", or "without asking how", could not offer any rationale. Instead, Islam needed rational theologians who could "make sense" of the faith. And these were none other than the Mutazila. This effort for a rationally consistent "dawa" (call) explains all the doctrines of the Mutazila that more dogmatic Muslims found unnecessarily complicated, if not outrageously heretical.
For example, the Mutazila opposed the popular belief in predestination, or "qadar", arguing instead that God had given human beings complete freedom and power in their acts. For otherwise, they realised, they could not defend God’s justice – a pivotal principle in their system – in rewarding or punishing people for their deeds. (They had also seen how the doctrine of predestination was used by the despotic rulers of the Umayyad dynasty, which dominated the Islamic Empire from 661 to 750, to instil unquestioning obedience to themselves.)
Another doctrine of the Mutazila which many Muslims have found baffling was that the Koran was God’s "created" word – instead of pre-existing with God Himself since eternity. The reason was their realisation that an "uncreated Koran" would vindicate the Christian doctrine of "uncreated Christ" — as the Christian theologian John of Damascus (d. 749) had intelligently argued. (Because Christ, too, was the "word of God", according to none other than the Koran.)
In other words, by defining the Koran as "created", the Mutazila were not devaluing it. Instead, they were trying to guard the core teaching of the Koran, which is God’s absolute unity.
The conceptualisation of Sharia law
Yet perhaps the most significant idea of the Mutazila was their conceptualisation of divine law – Sharia. It came from their answer to what is known to moral philosophers as the Euthyphro dilemma: is something "good" or "bad" because God commands or bans it? Or does God command or ban things because they are inherently "good" or "bad"?
With arguments based on the Koran – which commands "maaruf" (known good), referring to humans’ ethical knowledge – the Mutazila defended the second view above, often called "ethical objectivism". In this view, divine commands, revealed as Sharia, educated Muslims about objective ethical values that were already in the nature of things and knowable to human reason. Murder was inherently evil, in this view, and Sharia only indicated this truth, which would be still valid otherwise.
The opposite view – which later dominated Sunni Islam – was what philosophers call "divine command theory". In this view, God’s commands, revealed as Sharia, did not indicate but constituted moral truths. So, murder was wrong only because God banned it. If God had commanded it, then it would be perfectly right, because there was no measure of "good" and "bad" other than Sharia.
These two opposite theologies about Sharia had serious implications for its interpretation.
One was the thorny issue of hadith, the reported words and deeds of the Prophet Muhammad. Unlike the Koran, on whose authority all Muslims agreed, the authenticity of these orally transmitted reports, mixed with hearsays and forgeries, was doubtful. That is why most jurists in Iraq – early Hanafis, including the Mutazila – accepted only a limited number of frequently transmitted hadiths, paying most of their attention to the Koran and human reason. As such, they were called "Ahl al-Ray" ("People of Reason").
The opposite camp was "Ahl al-Hadith" ("People of Hadith"). They held that hadiths should guide Muslims on every possible question – thus leaving the minimum need for reason – and that their authenticity could be confirmed by establishing an unbroken chain of narrators (A heard from B, who heard from C, who heard from Muhammad, without a missed link in the chain). Spearheaded by Imam Ahmad ibn Hanbal, the staunchest adversary of the Mutazila, this movement ultimately produced the major "six books" of hadith, which continue to be revered today.
Calling the hadiths into question
A key difference between the two camps was whether the content of hadiths could be questioned using reason. For the Ahl al-Hadith, once the chain of narrators was established and the hadith was confirmed as "sahih" (authentic), there was little left to discuss. It became a canonical text that simply had to be accepted and obeyed. For the Mutazila, however, any hadith, regardless of its chain of narrators, could be questioned by judging its content – in light of both the Koran and human reason, including moral intuition.
Here is an example. Ibn Hanbal’s hadith collection, "Musnad", included a narration from Muhammad which read: "The believers and their children will be in Paradise, and the polytheists and their children will be in Hell." The latter part reportedly "upset" Muhammad’s wife Khadija, as it would offend the conscience of most of us. But did conscience count as a yardstick in religion?
The Mutazila emphatically said yes. "God would not punish children," wrote Ibrahim al-Nazzam (d. 845), "because that would make Him an oppressor, which He is not." Two centuries later, the last great Mutazila scholar and judge Abd al-Jabbar (d. 1025) also commented on such hadiths that are morally unacceptable, writing: "It is not permissible to abandon the rational faculties that God the Exalted has ingrained in us in favour of such reports."
Luckily, the children-in-hell hadith had a flaw in its chain, so it was ultimately classified as "weak". Yet many Muslims today read other interpretations that weigh heavy on their conscience: "sahih" reports that command obedience to corrupt tyrants; servitude to capricious husbands; or killing people, merely for their beliefs, as "apostates".