analogical reasoning, one of the four sources of Islamic law
The principle of deriving new judicial decisions by way of analogy with those given in the body of Hadith or the Qur`an. One of the four roots of fiqh recognized by Sunnis. From qasa, to gauge, measure, compare, correlate.
analogical reasoning; the fourth source of legal knowledge, following Qur'an, Sunna, and consensus ( ijma‘)
Literally this means measure, example, comparison or analogy. Technically, it means a derivation of the law on the analogy of an existing law if the basis (‘illah) of the two is the same. It is one of the sources of Islamic law.
logical deduction by analogy.
In Sunni Islamic jurisprudence, qiyas (Arabic قياس) is the process of analogical reasoning from a known injunction (nass) to a new injunction. According to this method, the ruling of the Quran and sunnah may be extended to a new problem provided that the precedent (asl) and the new problem (far) share the same operative or effective cause (illah). The illah is the specific set of circumstances that trigger a certain law into action.
