Resumen: In his first legal texts (1912-1922), Schmitt repeatedly engages in criticizing what is known as “legal positivism”. His main objection, as it is well seen in Law and Judgment (1912), is that this theory remains in the pure abstraction of legal texts and does not take into account the concrete aspects of reality to which the normative categories should apply. This work aims to justify that in those first texts, the German thinker identifies that one of the main issues of legal positivism lies in the fact that it is built based on an inadequate ontological interpretation of the human being. In particular, we will argue that Schmitt defends an understanding of the legal phenomenon that is constructed based on the consideration of concrete human existence, which in turn means the recognition of certain fundamental and original structures that operate in all human knowledge.