Qiyas

Qiyas (قياس), meaning "measuring" or "analogy," is the fourth principal source (aslā) of Islamic law after the Qur'an, the Sunnah, and Ijmā' (consensus). It is a method of ijtihād by which a jurist extends an established ruling (hukm) from an original case explicitly governed by the Qur'an, Sunnah or consensus to a new, unaddressed case, on the ground that both share the same effective cause ('illah). Its textual sanction is most commonly derived from Qur'an 4:59 ("refer it to Allah and His Messenger"), interpreted as a command to reason from revealed principles, and from the Prophet's dispatch of Mu'ādh ibn Jabal to Yemen, who affirmed he would exercise his own ijtihād where the Qur'an and Sunnah were silent. Imam al-Shāfi'ī (d. 820 CE) in his Risāla systematised Qiyas as a disciplined legal instrument, distinguishing it from arbitrary opinion (ra'y).

Every valid Qiyas rests on four pillars (arkān): the original case (asl), the new case (far'), the ruling of the original case (hukm al-asl), and the common effective cause ('illah) that links them. The classic illustration is the Qur'anic prohibition of khamr (grape wine) in verse 5:90; jurists identified its 'illah as intoxication (iskār) and extended the prohibition by Qiyas to all intoxicants, including modern narcotics and distilled spirits not known in the revelatory period. Identifying the 'illah — through methods such as textual indication (nass), consensus, or takhrīj al-manāt (extraction of the operative cause) — is the most demanding intellectual task and the chief source of juristic disagreement.

Acceptance of Qiyas is not universal across the schools. The four Sunni madhāhib — Hanafi, Maliki, Shafi'i and Hanbali — all admit it, the Hanafis employing it most expansively alongside istihsān (juristic preference). The Zāhirī school, founded by Dāwūd al-Zāhirī and championed by Ibn Hazm (d. 1064 CE), rejected Qiyas entirely as unwarranted addition to the divine text. Twelver Shia jurisprudence likewise rejects analogy as a source, substituting 'aql (reason) within its usūl framework. In contemporary practice, Qiyas underpins reasoning in Islamic finance fatwas, bioethics rulings on organ transplantation and IVF, and the work of bodies such as the Islamic Fiqh Academy (Jeddah).

For the CSS Islamic Studies paper, Qiyas is a recurrent question across the Sources of Islamic Law and Usūl al-Fiqh sections. Examiners typically ask candidates to define Qiyas, enumerate and explain its four arkān, distinguish it from Ijmā' and istihsān, and discuss the khamr–intoxicant analogy. Strong answers cite al-Shāfi'ī's Risāla, the Mu'ādh ibn Jabal hadith, and the Zāhirī and Shia objections, demonstrating command of both the mechanism and the inter-school debate. A comparative angle — Qiyas as a controlled bridge between fixed revelation and evolving social need — earns the highest marks.