Some of the Shai’a Muslim scholars like Al-‘allamah of Hillah, Iraq believe that the Qiyas in which the whole cause for the rule of Shari’a is clearly stated and the primeval Qiyas are exception to the invalid Qiyas but some of others disagree.

 In reality, the stated cause and primeval Qiyas if so formed are Hujjah but not as exceptions but as being different forms of inference. They fall under the category of unequivocal statements for the following reasons:

 The Stated Cause.

 To explain the following should be examined.

"It is unlawful to drink wine because it is intoxicating."

This rule can be applied to beer also because of the existence of the intoxicating quality in both cases.

On the other hand in the statement like, "This grape is sweet because its color is black," does not mean that every thing black is sweet.

 As a matter of fact, if the text would say that the stated cause is universal it will have the effect of a universal term and, therefore, a correlative relationship between the universal term and its applicable instances will be established. Consequently, one would have to deal with it just as is the case with the rest of the texts of the holy Quran and the statements of Sunnah. In the above mentioned Hadith about wine and applying the applicable rule to it, also to other intoxicants would be like applying the rule for a common term to its single instances. In such a case, it will not be considered an exception to Qiyas. It will be listed under a different category the category of the Statements of the sources of Shari’a.

 Another such example is the Hadith narrated by Ibn Bazi’ that says, ". The water of a well is quite a large amount and nothing corrupts it…. because it has a source. Which means that waters that comes from or is connected to a source is a large quantity and does not become corrupted by any thing The water of a well is only one instance. It applies to the water from the tape; a brook and fountains are other instances. Applying the above rule to various instances is not a Qiyas but it is application of meaning of common term to its particular instances. No causation condition is involved in the above mentioned text but it is the question of a source of water. This rule will not apply to unclean water with sources which is mixed with non-water substances and can not be considered pure water any more even though it may have a source. Because doing so will make the process a Qiyas which is not a Hujjah.

 This will make Qiyas distinguishable from the application of the rules and unequivocal meaning of common terms to its instances. The two cases need careful examination to avoid confusions.

 This will also clear the confusion between those who consider the case of stated cause rule as Hujjah and those who do not consider as such. Considering it as Hujjah is because of considering it under the category of unequivocal meaning of a common term and considering it as non-Hujjah is because of considering it as an example of Qiyas.

In short, if the case of stated cause would fall under the category of common term and its unequivocal instances then it is out of the limits of Qiyas, otherwise, expanding to other cases would become inference in the form Qiyas that is not considered as Hujjah.