Carnap"s program of rational reconstruction (or explication) excludes external ontological questions as pseudo-problems — at least if these questions are treated as theoretical questions and not as questions of pragmatic decision. The same already holds for the question of whether there exists an external world (independently of the subject of knowledge) or not. This position is very similar to that of Heidegger. The reason for this similarity is that Carnap and Heidegger share a common origin in neo-Kantianism, ">Lebensphilosophie and phenomenology. In order to elucidate the philosophical relations between Carnap and Heidegger (beyond what is already well established), I will introduce as "the third man" to this story Oskar Becker. An explication of Becker"s philosophical ruminations on the problems of ontology will help us to mediate between the positions of Carnap and Heidegger and to come to a positive evaluation of their common views.