The problem of rationality today means the problem of the inner unreasonableness of reasonableness in the sense of its inner limit. Even the humanistic revolution of the Renaissance gradually led to the replacement of the power of omnipotent faith by faith in the omnipotence of power. It is this general orientation towards power and the cult of power, this new belief in power, that revealed itself more and more sharply in the course of European history and eventually led to extreme forms of expression in the world wars and catastrophes of the twentieth and twenty-first centuries. The activity of free reasonableness has resulted in a host of unreasonable consequences: we have reason to suggest that reasonableness perhaps contains its own negation. Most philosophers of the twentieth century supposed that today it is impossible to think as in former times; it is already impossible to imagine reality as the structure which alone has a basis. The modern pluralistic world cannot be interpreted in a single rationalistic way as the only possible way, which would lead to the world’s being be united on a single principle for the sake of final truth. The philosophical world of the twentieth century “shivers” because of the fluctuation its own foundation, which was recently the symbol of its firmness and absoluteness. The article offers an analysis of a foundation of this kind, viz. evidence. The tradition of this concept leads us to Descartes and back to the three main versions of transcendentalism: Kant’s, Husserl’s and Heidegger’s. The author finally comes to the conclusion that the appearance of overcoming the metaphysical approach in the twentieth century is replaced by a transcendental and dialectical “game” around metaphysical concepts.