Science often claims to apply reason and act rationally. However, the understanding of "reason“ and "rationality“ might be different and is not always transparent. Based on extensive analysis of existing concepts, Czarnocka offers a new concept of scientific reason. She shows that scientific reason is methodical and not instrumental and its basic forms are universal, i.e., they determine rules of cognition and action in all the human experience. She also argues that methodical reason grows out of subjective reason and ultimately from objective anthropic reason, i.e., from the foundations of human collective wisdom, as well as from ontic reason. The author claims that there is a three-layer hierarchy of reasons linked by the relation of conditioning. Methodical reason is conditioned by subjective reason, and this in turn is conditioned by the deepest layer which includes two objective reasons—anthropic reason and ontic reason. Moreover, she reveals that the problem of reason in science not an isolated problem of science itself, but is related to issues of human nature and of culture, as well as the problems of collective human wisdom and ontic nature of reality.