Whenever Points of law arose in the umma (islamic nation or community) which were not covered by a detailed statement in the Qur'an or the Hadith, the majority of theologians and jurist had a recourse to analogical deduction which means Qiyas in Arabic.
In the other words, Qiyas means the application to a new proplem of the principles underlying an existing decision on some other point which could be regard with the new problem. Thus the Ulamã or doctors of religion arrived at our answer by deduction from decisions in similar or parallel cases.
Literally, Qiyas means to compare but according to islamic theology it is the analogical reasoning of the learned with regard to the Qur'an the Hadith and Ijma. There are 4 conditions of Qiyãs:
• That the precept or the practice on which it is founded must be of common (Ä€mm) and not of special (Khãss) application.
• The couse of the injunction must be known and understood.
• The decision must be based upon either the Qur'an the Hadith or Ijmã.
• The decision arrived must not be contrary to anything declared elsewhere in the Qur'an or the Hadith.
There are two kinds of Qiyas: Qiyas al-jali or the evident Qiyas and Qiyas al-Khafi, the hidden Qiyas. As for example, wine drinking is forbidden in the Qur'an under the general term "Khamar" which means anything intoxicating. It is therefore evident that upium and all intoxicating drugs are also forbidden. Similarly in the Hadith it is enjoined that one goat in forty must be given as Zakat. To some poor and needy people the money equivalent to it may be more acceptable; therefore, the value of the goat may be given instead of the goat Itself.