Abstract: The essay addresses the meaning of boundary situations in the philosophy of Karl Jaspers, as a turning point drawing on Edmund Husserl's phenomenology and Immanuel Kant's transcendental philosophy, and as a key for the comprehension of some of the differences in Karl Jaspers' philosophy regarding the thought of Husserl and Kant, respectively. For Jaspers, the meaning of boundary situations as a structure of Existenz underlines the possibility of risk in the individual historicity. Taking risks breaks the flow of reflection (...) and, at the same time, appeals to an opening of ethics—without sacrificing the universality of Kant's categorical imperative. From Jaspers' point of view, Husserl's phenomenology does not open the possibility of self-transformation of the self, nor contributes it to the unfolding of the "inner action" of the transcending thinking, and since the boundary situations break the flow of the selfreflective consciousness, tensions arising between consciousness and Existenz remain beyond the scope of Husserl's phenomenology. Similarly, as seen from Jaspers' position the meaning of Kant's transcendental method has become different after the clarification by the Existenz, which not only shows that thought is at stake in boundary situations, but also that Existenz at the same time puts its potentiality and its fate at stake. (shrink)