Based upon fieldwork in several West African societies and one South Asian society the paper demonstrates patterns of knowledge acquisition and knowledge transformation. Three modes of intellectual operation can be distinguished: empirical evidence, deduction and moral authority. The processes of erosion and reconstitution of certainties are basically identical in the whole spectrum of human societies. It is only different forms of embedding the knowledge processes that allow experience, deduction and moral authority to be recombined in different ways. The wish to control stochastic events may produce appearances of spirituality. The closed minds hypothesis, however, finds no confirmation. Science appears in this perspective as refined common sense based upon an institutionalized differentiation of knowledge. Within this institutional realm, however, para-science may find a place.