One of the criteria that has been used for distinguishing and compiling sciences since long ago is the criterion of “essential accident”. By having this criterion, scientists will be able to put together propositions specific to a certain subject correctly and in a logical order, and draw a specific boundary for their desired science. However, Ayatollah Mesbah introduces problems to this criterion, which makes this criterion invalid in the Philosophy. This article tries to explain with a descriptive-analytical method and according to the available references, first explain a summary of the criterion of “essential accident”, then discuss Ayatollah Mesbah's problems with this criterion in compiling the Philosophy.       The “essential accident” nature of the predicate for the subject depends on the achievement of two major conditions, namely "inherence" and "priority", and the problems of Ayatollah Mesbah are also related to these two; However, it is possible to answer these problems by paying attention to the problem of the participation of term and proof and also comparing the conditions of philosophical secondary intelligibles to the predicates of the subject the Philosophy.