 Thus, in outline, a generalization scheme in physics is presented as follows: From the phenomenon we move by physical induction to the experimental result and, thanks to differential equations, to the laws and the general hypotheses which, by a common decision of the scientific community, can be elevated finally to a principle. Certainly this is only a general scheme and the concrete process of a generalization could include many variations. The difference between the geometric axiom as a “disguised definition” and the physical law as a principle seems to define Poincaré’s epistemological criterion that distinguishes geometry from mechanics from the ontological point of view. In geometry, the convenient conventions (or definitions) are chosen as a function of objects (solid bodies, rays) which are not the objects of the geometry. Furthermore, in geometry we presuppose the category of group, so geometry requires a double conventional abstraction. In mechanics, the conventions are useful and apply to physical objects (Poincaré 1902: 152; 2017: 100). In this context we presuppose the categories of empirical or physical induction and of differential equations as necessary preconditions for doing science. Poincaré’s approach therefore integrates specifically Kantian elements, the idea that there are preconditions, while still completely eliminating the transcendental basis of these components that we find in Kant’s thought.