The best definition for Qiyas, in our opinion, is to say, " To establish and obtain a decision, a rule and judgment for a case due to a certain cause just because of the existence of the similar cause, rule and judgment in an other particular case."

The first case which is Maqis is called the Branch, the derivative (Far’)

The second case which is Maqisun ‘alayh.is called the Origin, the (‘asl)

The cause that is found in both cases is called the Common element (jami’)

In reality, the operation of inference in the form of Qiyas is a process that one may adopt to deduce a certain rule of Shari’a for a given case for which the rule is not mentioned in an available text of the holy Quran or the Sunnah. The process of inference in the form of Qiyas yields certainty, Yaqin (name for the degree of one’s knowledge of an object at least 100%) or Zann (the degree of knowledge between 50-99%) of the a given rule of Shari’a.

The process of inference in the form of Qiyas is the same as applying the rule that is already established for the ‘asl the origin according to the texts of Shari’a to the Branch and derivative, the Far’. In this way a rule for the branch and derivative is established that is similar to that for the original.

Thus, if the quality of the rule for the original is obligatory so it is for the derivative and the branch and if the rule for the original is a prohibition the same is true of the derivative and the branch.

What it means is that in so doing one renders a judgment. This judgment says that since the process of Qiyas has established for the branch a rule similar to the original case, thus, it should be the same according to the legislator of the Islamic Shari’a because of the common cause found in both cases; the original and the derivative.

This process gives one certainty that whatever rule is given to the branch is the real rule according to the legislator of the Islamic Shari’a.

This process or decision or inference or proof whatever one may call it serves as evidence of the rule that God, the legislator wants for the derivative and branch.

In a technical examination of the given definition of Qiyas above it (the definition) can still hold upto the logical requirements of inference such as the requirements of the syllogism, the middle, the minor and major terms. However, what serves as the middle term in this case is the belief of one who establishes the process.

On the other hand, if one would define Qiyas as a case wherein there is equal resemblance of causes in the Original and Branch it would apply to the case where Qiyas could be formed not the Qiyas itself.

One may not even need to go into greater details with a view to the fact that the matters about Qiyas are clear.