  We are interested here in the program of reconstruction of quantum mechanics
of the German physicist and philosopher Carl Friedrich von Weizs\"{a}cker,
which still has some supporters today. In the major part of this article, we
limit ourselves 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 alternatives (or Ur-alternatives) of
von Weizs\"{a}cker 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.
