وللفصل نسبة إلى النوع، فيسمى مقوما؛ لدخوله في قوام النوع وحقيقته.
In relation to a species, differentia is called constitutive because it enters into the species' constitution and essence.
Rational is constitutive (muqawwim) of human. It is a defining element in the classical analysis of the species, not an accidental event that happens to particular humans.