The principle “quiddity as such” is one of the important principles in Islamic philosophy, employed in various discussions to substantiate philosophical claims. Its core assertion is that the essence of quiddity is devoid of any determination or attribute, except its own essence and intrinsic properties. This article examines the content of this principle in relation to the concept of existence in two respects. In the first respect, which involves the negation of absolute existence from the level of essence, several critiques are presented. These critiques are based on the argument that a quiddity, even in its essential aspect, cannot remain indifferent or “unconditioned” with regard to certain instances of existence - such as “existence in nafs al-amr” and the “existence of genus and differentia in definition”. In the second respect, concerning the negation of “external existence” from the essence, further critiques arise. The most significant is that the external existence of a quiddity is what preserves its essence and intrinsic properties. Moreover, the principle appears increasingly incompatible with the widely accepted interpretations of “the primacy of existence and the mentally posited nature of quiddity.” Based on the findings of this study, this principle does not function effectively when confronted with the issue of existence in philosophy and requires serious reconsideration. Accordingly, any claim proven on the basis of this principle must be substantiated through alternative arguments.