This paper addresses discussions in post-Avicennan Arabic logic on the definition of metathetic propositions and their status in relation to existential import requirements, focusing on the arguments made by Fakhr al-Dīn al-Rāzī (d. 606/1210) and the counter-arguments by Quṭb al-Dīn al-Rāzī al-Taḥtānī (d. 766/1365), who both establish their positions in the framework drawn by the most prominent figure in the tradition of classical Arabic logic, Avicenna (Ibn Sīnā, d. 428/1037). In the latter’s works, the problem of the existential import requirement in metathetic propositions (ma‘dūla) are thoroughly discussed and Avicenna seems to have presumed the existential import as a truth-condition for affirmative propositions, and therefore, affirmative metathetic propositions. For Avicenna, in other words, an affirmative metathetic proposition presumes its subject-term’s possibly existent referent(s). However, the theologian-philosopher Fakhr al-Dīn alRāzī, who lived about a century and half after Avicenna, raised criticisms against him in terms of metathetic propositions and their existential import among other things and ignited a wave of debates in the tradition, in which Quṭb al-Dīn al-Taḥtānī took place in the following century. Through a study of this contained problem, this paper aims to address a wider scholarly concern regarding the vitality of post-classical Arabic logic. By studying the issue of existential import in metathetic propositions, this paper seeks to establish that in fact, this period was witness to the flourishing of philosophical debate among Arabic logicians.