Qīyās (Arabic: قیاس) or analogy is a term in usul al-fiqh (principles of Islamic jurisprudence) which means the application of the jurisprudential ruling of an issue to another analogous issue on which there is no ruling in religious texts. There are various types of qiyas, including: qiyas mansus al-'illa (qiyas with explicitly mentioned cause), qiyas mustanbat al-'illa (qiyas with inferred cause), qiyas al-awlawiyya (a fortiori qiyas), and tanqih al-manat (isolation of the criterion). There is a disagreement between Shiite and Sunni scholars regarding the validity of qiyas with inferred cause. Shiite scholars rely on hadiths from the Imams (a) and believe that it is invalid, but Sunni scholars take it to be valid. The first person who made an extensive use of qiyas in fiqh (jurisprudence) was Abu Hanifa. The majority of Shiite scholars take qiyas with explicitly mentioned cause, a fortiori qiyas and the isolation of the criterion to be valid.
In usul al-fiqh, qiyas refers to the application of the ruling of an issue to an analogous issue on which there is no ruling in religious texts. For example, religious texts explicitly forbid the drinking of the grape wine, but there is no text regarding the ruling of the date wine. Qiyas can be employed here by saying that the grape wine is forbidden because of its intoxication, and since the date wine is intoxicating, it should be forbidden too.
It should be noted that "qiyas" in fiqh and usul al-fiqh has a different meaning from that in logics. The qiyas in usul al-fiqh has the same meaning as "tamthil" (analogy) in logics. In logics, however, "qiyas" is used to refer to syllogisms which are valid forms of arguments, but in logics, the analogy, or "qiyas" in usul al-fiqh, is not considered as valid.
Essential Elements of Qiyas
According to scholars of usul al-fiqh, qiyas has four parts or essential elements:
- Analogatum: the issue whose ruling is mentioned in religious texts, such as the grape wine in the above example,
- Analogans: the issue which is similar to the analogatum, but its jurisprudential ruling is not mentioned in religious texts, such as the date wine in the above example,
- Cause or criterion: a similarity between the analogatum and the analogans, such as intoxication in the above example,
- Ruling: the jurisprudential ruling of the analogatum which is supposed to apply to the analogans, such as the prohibition of drinking the grape wine in the above example.
Varieties of Qiyas
There are different types of qiyas the best known of which are as follows:
- Qiyas mansus al-'illa (قياس منصوص العلة) (qiyas with explicitly mentioned cause): it refers to a qiyas where the ruling of the analogatum involves reference to its cause as well. For example, if there is a hadith that forbids drinking the grape wine because it is intoxicating, it will turn out that the cause or the ground of its prohibition is its intoxication. This will imply that everything that intoxicates is forbidden. Such a qiyas is also known as "jali" (الجلي) (obvious) or "musarrah al-'illa"
(مصرح العلة) (with explicitly mentioned cause).
- Qiyas mustanbat al-'illa (قياس مستنبط العلة) (qiyas with inferred cause): in this type of qiyas, the cause or ground of the ruling of the analogatum is not explicitly mentioned, but the jurist makes guesses about its cause. This is also known as "khafi" (الخفي) (hidden).
- Qiyas al-awlawiyya (قياس الاولوية) (a fortiori qiyas): in this type of qiyas, the cause or ground of the ruling of the analogatum much more strongly holds in the analogans, thus if the ruling in the analogatum is prohibition, then the analogans will a fortiori be prohibited, and if the ruling of the analogatum is an obligation, then the analogans will a fortiori be obligatory. For example, there is a verse in the Qur'an according to which one should not say "uff" (اُفّ) ("Fie", an expression of frustration) to one's parents. Thus, a fortiori it will be forbidden to hit one's parents, because hitting them is worse than saying a word of contempt.
- Tanqih al-manat (تنقيح المناط) (isolation of the criterion): this is a type of qiyas in which the criterion of the ruling is uncovered by examining the features of its subject-matter and identifying the relevant features. Then, the ruling is generalized to any subject-matter that has the same relevant features. According to some people, the isolation of the criterion is not a type of qiyas.
Views of Islamic Sects
The problem of qiyas is a controversial issue over which Shiite and Sunni scholars have disagreed. According to Shiite scholars, qiyas is not valid because of many hadiths from the Imams (a) in which qiyas is prohibited. For example, there is a hadith from Imam 'Ali (a) cited in Tuhaf al-'uqul: "do not make qiyas (analogy) in the religion, because the religion cannot be measured by qiyas". There is also a hadith from Imam al-Sadiq (a) according to which if qiyas is made in the religion, then the religion will be wiped out. But Sunni scholars maintain that qiyas is valid. The first person who made an extensive use of qiyas in fiqh was Abu Hanifa. However, it is said that the use of qiyas had precedents prior to Abu Hanifa. For example, the first, the second, and the third caliphs employed qiyas in issues on which there was no explicit ruling.
Given that there are different types of qiyas, it should be noted that the main controversial issue here is the qiyas with inferred cause which is totally speculative. The majority of Shiite jurists take the a fortiori qiyas, qiyas with explicitly mentioned cause, and the isolation of the criterion to be valid.
Imam al-Sadiq's (a) Debate over the Qiyas
In his book, al-Ikhtisas, al-Shaykh al-Mufid reported a debate between Abu Hanifa and Imam al-Sadiq (a) over the validity of qiyas. Imam al-Sadiq's (a) arguments against qiyas are as follows: Imam al-Sadiq (a) said, "O Abu Hanifa! Which one do you think is more significant; adultery or murder?" He said, of course, murder. The Imam said, "so why did God rule that the testimony of two men suffices in the case of murder, while for adultery the testimony of four men is required? How can this be justified in terms of qiyas? O Abu Hanifa! Which one is worse, the abandoning of the fast or the abandoning of the prayer?" He said, of course, the abandoning of the prayer. The Imam said, "so, why should a woman perform the qada' of her fasts during her menstrual periods, but it is not obligatory for her to perform the qada' of her prayers? How can this be justified in terms of qiyas? Woe to you, Abu Hanifa! Are women weaker in business or men?" He said, of course, women. The Imam said, "so, why did God allocate two shares of heritage to men and only one share for women? How can this be justified in terms of qiyas? O Abu Hanifa! Is one's feces dirtier or his semen?" He said, of course, feces. The Imam said, "so, why did God rule that it is sufficient to wash the affected area to clean the feces, but for the semen, He required ghusl? How can this be justified in terms of qiyas?"
- The material for this article is mainly taken from قیاس in Farsi WikiShia.