The Principality of "Non-Addition" (ʿadam al-ziyāda) and its conflict with the "principality of non-deficiency" (iṣālat ʿadam al-naqīṣa) have been brought up and discussed by jurists and scholars of legal methodology. It is commonly held by the scholars of ʿIlm al-Uṣūl that the Principality of "Non-Addition" is preferred over the "principality of non-deficiency". Some scholars, however, maintain that in case of a conflict between the two principles, they both cease to operate and that neither of them takes precedence over the other in case of doubt. Of course, many scholars have briefly and cursorily touched on this topic and have not presented a detailed and argumentative discussion in this regard. According to the writer of the article, many basic rules, such as the subject matter, need a comprehensive and independent study. The discussion concerning the principality of "non-addition" and its conflict with the "principality of non-deficiency" is of paramount importance inasmuch as it plays an important role in jurisprudence. In this article, a new and innovative perspective has been proposed which we shall critically and scientifically assess in the upcoming issue of this journal.