This article aims at presenting : – 1. The innovations of Ernst Cassirer's open epistemological model, transforming the concept of ‘constituting objectivity’ by founding it on the dynamical ‘constitution of meaning‘; – 2. The entailed conception of physics‘ objectivation as a process of ‘symbolic formation‘, studying its transcendental functions and their roles for the major tasks of creative constitution and pragmatic justification of knowledge; – 3. The clarifying and convincing solutions this view offers for the interpretation of relativity theory and quantum mechanics. It leads to the conclusion that the transcendental method might be the best way to fulfil the realist‘s claim.