I present first the challenge for epistemology when it faces the dilemma between rationalism and empiricism, followed by a presentation of the ideas introduced by Ruyer in order to ask if they can be articulated to the "third way" in epistemology. I explore the consequences of Ruyer's inversion of our understanding of space which can be looked upon as psychic. I consider Ruyer's refusal to locate in pure immanence the scheme of eupraxic resolution of successful aggregates–as living forms–in our experience. I then highlight the major principles of Gaston Bachelard's and Michel Serres's respective epistemologies, and in a lesser measure those of Bergon and Deleuze as well, in order to underscore Ruyer's refusal to limit philosophy to what science allows one to say, but also in order to finally situate the verticalism of his position
