Regulation the rule of Incapability of being specialized

This article surveys the rule of incapability of being specialized and introduces some regulations to find out the main reason of this rule. Although this rule is used in several problems by the scholars of fiqh and usul al-fiqh, issues in which this rule must be used are not clearly explained and in some cases this rule are used without any reason. The goal of this article is to survey rules and regulations by which find the reason of Incapability of specialized and based on a recognized criteria identify those reasons that are incapable of specialized. Accordingly the author through a descriptive and analytic method tries to identify the concept of the rule and through analysis the words of scholars finds some criterion to recognize incapability of specialized. What are found are introduced in five general rules. Some of which lead to identify the incapability of specialized by itself and some others need the addition of some other signs.