Conflict between Istishab Sababi and Istishab Mosabebi and its application in Law with Special Reference to Imam Khomeini's Viewpoints

The conflict between istishab sababi and istishab mosabebi means that doubt in one is caused by doubt in the other. This is a subject matter of the Principles of Jurisprudence. It was put forth for the first time by Sheikh Tusi and after him other experts of the Principles of Jurisprudence too discussed it. There is no doubt that istishab sababi is prior to mosabebi, but the controversy is about the reason and basis of this priority. Some of the jurisprudents maintain that istishab sababi governs istishab mosabebi and if istishab sababi is enforced, there is no room for istishab mosabebi. Others believe that the priority is based on launching, while others argue that if istishab mosabebi is given priority, a vicious circle will appear. Therefore, in order to avoid vicious circle istishab sababi should be given priority over istishab mosabebi. Imam Khomeini maintains that if istishab is of rational or normative kind, the istishab sababi would not have priority over istishab mosabebi, but if it is canonical (Shari), the inferential (ijtihadi) whose context is prepared by the istishab sababi, in this case istihab mosabebi is given priority.