Qiyās means ‘analogy’ or ‘syllogism’, and more broadly, ‘reasoning’. It implies the inference from the known to the unknown, allowing one to obtain new knowledge on the basis of previously existing knowledge.
In Islamic law, qiyās is understood as ‘analogy’ and it constitutes one of the sources of the law, alongside the Qur’ān, the Sunna and consensus (ijmā‘). The use of analogy meant that legal decisions on new cases were formed on the basis of previously known cases in the Qur’an and the Sunna. Various jurists restricted the use of analogy and stated that its results only yielded probability and not certainty, since the Qur’an and the Sunna were the most important sources of Islamic law.
It is considered that analogy began to be used in the 2nd century of the Hijra and was first used systematically by Abū Ḥanīfa (d. 150/767). Analogy was avoided by the traditionists (aṣḥāb al-ḥadīth). Al-Shāfiʿī (d. 204/820) identifies ‘analogy’ with ‘ijtihād’, the personal intellectual effort of a jurist to reach a legal verdict on a new case. At any rate, a textual base within the religious texts was required for the use of analogy. An example of analogy would be the prohibition of taking any intoxicating substance in view of the fact that the Qur’an prohibits the drinking of grape wine, because it is intoxicating.
Qiyās is also used in Arabic grammar to indicate a ‘norm’ for a word and its usage when transmission does not provide it.
In classical or medieval Islamic philosophy, qiyās means ‘syllogism’ and it translates syllogismos, the term used and developed by Aristotle in his Prior Analytics in the context of his writings on formal logic. It is composed of two premises, major and minor, and a conclusion. The middle term links the two premises. The major premise contains the main term, which appears as predicate in the conclusion, and the minor premise contains the minor term, which appears as subject in the conclusion. If the information contained in the premises is correct and the form of the syllogism is valid, a valid and truthful conclusion ensues.
As in Aristotle’s syllogistic logic, a syllogism for Arabic Islamic philosophers bears different forms in the way it contains premises with universal or particular terms, and whether the premises are affirmative or negative. In addition, the syllogism is an instance of the process of causality, in the sense that the premises are considered to be the cause of the conclusion.
There are different types of syllogism, such as certain (which yields a certain conclusion) and conditional (conjunctive or disjunctive). Syllogisms based on hypotheses are hypothetical, and according to Alfarabi (d. 339/950) any conditional syllogism is also a hypothetical syllogism.
Alfarabi distinguishes up to fourteen types of syllogism. The first figure, which contains universal affirmative premises, is the perfect type of syllogism, as it was for Aristotle. He also distinguishes dialectical, rhetorical and sophistical syllogisms.
Avicenna (d. 428/1037) mentions a ‘relative’ or ‘relational’ syllogism, going back to Galen. For Avicenna, a perfect syllogism is evident and does not require further proof. He also develops the modal syllogism.
In The Decisive Treatise, Averroes draws a comparison between analogy (qiyās fiqhī, juridical reasoning) and syllogism (qiyās ‘aqlī, intellectual reasoning) to establish the similarity between religion and philosophy and the harmony between the two disciplines. He argues that, in the same way that juridical reasoning is considered an essential part of Islamic jurisprudence, which is an Islamic discipline, so in the context of more general inquiries about the nature of reality intellectual reasoning, or syllogism, should be studied and used. Since the Ancients developed the art of syllogism, it ought to be studied by Muslims who have the aptitude to study philosophy. Averroes seeks to show that studying ancient philosophy, and particularly Aristotle, is incumbent on some Muslims, and also that philosophy should be considered an Islamic discipline, in the same way as jurisprudence (fiqh).
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Author Citation Information:
<Bela, Catarina, “Qiyas,” ODIP: The Online Dictionary of Intercultural Philosophy (2012), Thorsten Botz-Bornstein (ed.), URL = <>.