ʿAllāmah Ṭabāṭabāʾī, based on his distinctive interpretation of the primacy of existence (aṣālat al-wujūd) and the mentally posited nature of quiddity (iʿtibāriyyat al-māhiyya), as well as his particular analysis of the problem of mental existence, assigns different rulings to quiddities as opposed to existents, non-existents, and their attributes. This leads to the confinement of acquired knowledge to quiddity and presential knowledge to existence. On this basis, he offers innovative definitions of both acquired and presential knowledge. ʿAllāmah further maintains that acquired knowledge of the Necessary Being and the presential knowledge of quiddities is rationally impossible. This study, employing a descriptive–analytical method, examines these philosophical issues from the standpoint of Ustād Fayyāzī. Through comparative analysis, it highlights the significant divergences arising from the differing interpretations of the primacy of existence held by these two thinkers. Ustād Fayyāzī offers an alternative reading of primacy of existence and considers the arguments for mental existence incomplete. He rejects the division of concepts into real and conventional, the separation of the concept of quiddity from existence and non-existence, the confinement of acquired knowledge to quiddity, and the confinement of presential knowledge to existence. He also denies the impossibility of acquired knowledge of the Necessary Being and the impossibility of the contingent and Necessary Being’s presential knowledge of quiddities. He considers the foundational premises under discussion as the reason for these philosophical conclusions.