Abstract

                 Knowledge is the life and perfection of the soul, and its quality is to know what it is and what it has. And its a faculty that does not happen except without its origins, so it is necessary to know the principles before they arrive, and its not a  secret that the scholars of Islam paid great attention to the science of the principles of jurisprudence, as it is the science approved in matters of discretion, by which reacheing the purposes of the Sharia, and the meaning of the words of the book and the honorable Sunnah of the Prophet on the specific meanings. There is no doubt that the topics that were included in the science of jurisprudence are the subject of contradiction and preference between the legal evidence that it is not possible to derive legal rules from the evidence except after knowing this topic and familiarity with its rules. The fundamentalists have paid great attention to this subject in their books, so that the diligent (Al-mujtahid) stops on what his approach necessitates, and is committed to proving the case of conflicting evidence, and what is required of him when making preponderance, because the one who realizes the difference between the evidence and prefers one of them is the diligent (Al-mujtahid), because the difference is according to his point of view