The subject of this article is to criticize and investigate the coequality of the theory of evolution and 'Motion in the Category of Substance' in regard to semantics and epistemology. Since both theories highlight gradual changing, can they be considered common and in the same direction? The two theories seem to have some differences in regard to semantics and epistemology such that they cannot be considered identical; because the theory of evolution is based on nominalism in regard to semantics, and does not accept the existence of the generic universal forms; and the changes in the theory of evolution means the change of one being to another but in the theory of motion in the category of substance it means transformation and this theory is based on universals and the specific forms. The coequality of the two theories of evolution and 'motion in the category of substance' is criticized and investigated in this article.