Validity of Istishab (Authorizing the Previous States) in Viewpoints of Imam Khomeini and Mirza Hassan Bojnourdi

The present article is a comparative study of the issue of Istishab (authorizing the previous state) from the viewpoints of two contemporary usuli jurisprudents, Imam Khomeini and Mirza Hassan Bojnourdi. The general Istishab is conceptual Istishab which can be applied to several people and is divided into three kinds according to the principles of jurisprudence. Imam Khomeini maintains that Istis-hab is applied in the first and second general kinds. The Imam has answered the questions regarding the second general kind by relying on the argument of advocates of common sense and then has explained the third kind by elucidating the way of considering common sense in individual characteristics or commonality of individuals. In his viewpoint, with regard to the third general kind, if common sense has taken individual characteristics into consideration, Istishab is not applied, but if the commonality of individuals is taken into consideration as subject of common sense, then Istishab is applied. The late Mirza Hassan Bojnourdi allows application of Istishab in the first and second general kinds and provides his answer to second kind by relying on the unity of nature of the definite issue and the issue under question. With regard to the third general kind, he argues that the criterion is unity of the advocates of common sense and hence, Istishab can be applied only when there are uncertain issues.