We are interested here in the program of reconstruction of quantum mechanics of the German physicist and philosopher Carl Friedrich von Weizsäcker, which still has some supporters today. In the major part of this article, we limit our- selves to examining purely epistemological and philosophical questions. The theory of the German physicist is often interpreted with reference to Kant, but the most of the time in a rather vague way (categories of understanding, theory of experience). We can afford to be more precise. First we situate the theory of fundamental alter- natives (or Ur-alternatives) of von Weizsäcker in the lineage of the Kantian theory of the transcendental Ideal. We then show that the physicist only substitutes for the classical logic, on which Kant relied, a quantum logic allowing to generate, from the alternatives, via the local isomorphism between certain spinor groups and groups linked to space-time, the whole of physical reality to which we have access. After examining some problems, we finally show how this perspective leads to a quantum theory of information.