Principality of existence and conventionality of quiddity can be considered as the main pillars of transcendental philosophy. This term has various interpretations each of which can be regarded as related to one dimension of that meaning. Thus, in the present article, we have attempted to review one of these interpretations (that of Master Gholam-Reza Fayyazi), and offer an explanation that seems to be closer to reality. Accordingly, in this article, we have stated Master Fayyazi’s foundations and offered a summary of his opinions regarding this principle to explain eight foundations and critiques about them, while explaining some part of semantic foundations that seems to be more correct. Besides, we have also investigated and reviewed the reason he has offered for his opinion on conventionality of quiddity with his special statement. We have continued with explaining and reviewing the most essential consequence of that statement, which seems not to be right. Therefore, in this article, we have attempted, while offering critiques of that statement, to present points for researchers in the transcendental philosophy to enable them to gain more of that philosophical school and come closer to the ontological depth of transcendental philosophy.