The issue of necessity is one of the most important aspects of Hegel's philosophy. The meaning of necessity per se or necessity alone is not discussed here, but here we consider only the two constraints used in Hegel's expressions for necessity. The subject of discussion, accordingly, is the two words used in Hegel's statements, namely external and internal necessity. In the first stage, this article deals with the external and internal necessity. In the second stage, it explains the relationship between the two. Then in the third stage we discuss the relationship between these two types of necessity and Hegel's science or philosophical system, and finally in the fourth step, an attempt is made to critique and evaluate this relationship.‏