In debates over the Christological doctrine proclaimed at the Council of Chalcedon, two different Christological stances took shape that in fact carried not only significant theological consequences, but also profound philosophical ones. In the present paper, I shall reflect upon the philosophical premises and arguments employed by both the defenders of Chalcedon and their adversaries. As I shall seek to show, both sides differed, among other things, in regard to their understanding of the individual entity as such. The Miaphysite adversaries of the Chalcedonian Horos adopted what was, from a philosophical point of view, a quite traditional elucidation of individual entities in terms of particular essence. On the other hand, the Neo-Chalcedonian defenders of the Horos developed an original interpretation of the individual entity as explicable in terms of its existence.