From Vladimiri's just war to Kelsen's lawful war: the universality of the "bellum justum" doctrine

The article explores Hans Kelsen’s theory of just war (bellum justum). It addresses the question of how and why the leading modern positivist thinker in fact embraced a key natural law theory, the concept of just war. In exploring this question, it collates the Viennese philosopher’s views with those of Polish late Middle Ages philosopher and lawyer, Paulus Vladimiri, who developed his own version of the bellum justum doctrine. In the first step, an outline of Paulus Vladimiri’s views on just war is presented. Secondly, the article offers an overview of two key theses of Kelsen’s theory of international law in order to provide the necessary context for his use of the term bellum justum. Next, the analysis moves to answering the question of whether Kelsen’s position might in fact be described as naturalist. In the last part, the article adds to some criticism of Kelsen’s use of the term “just war”. The conclusion underlines the points of intersection between the two doctrines. Although Kelsen’s attempt to harness the just war tradition within the confines of his own pure theory of law seems to have largely failed, it exemplifies a degree of universalism of the just war tradition and its potential for transcending divisions among schools of legal and philosophical thinking.