The article analyzes the ontology model formulated by Friedrich Dessauer in the monograph Man and Space. The subject of analysis is, on the one hand, the method used by Dessauer to distinguish four worlds (physical, biological, mental, and spiritual), on the other hand, the method of solving the problem of the interaction of worlds, which constitutes the original theory of activity. The latter underlies his philosophy of technology, formulated in the monograph The Dispute about Technology. Dessauer is a classic of the philosophy of technology, both analyzed monographs are available in Russian translation. The purpose of the analysis carried out in the article in the historical and philosophical terms is to identify methodological parallels in the models of the philosophy of technology by Peter K. Engelmeier, the philosophy of science by Karl Popper and actually by Friedrich Dessauer; in ontological terms in identifying the correlation of ontology, real science, and metaphysics in Dessauer's model, in terms of the philosophy of technology in identifying the minimum necessary structure of technical action in a pluralistic ontology. The research method is semiotic modeling, which consists in expressing the worlds in the form of independent complexes of pragmatic, syntactic, and semantic rules, where the interaction of the worlds is considered as an independent semiosis. The results of the study are, firstly, in the explication of Dessauer's ontology by means of semiotics, and, secondly, in the ontological substantiation of the thesis that the structure of the interaction of the worlds, as it is fixed and used in the scientific and technical worldview, is the structure of technical activity. Understanding the structure of technical activity, in turn, sets an ontological model of scientific and technological progress, which makes it possible to formulate an expert assessment of the current state of affairs, as well as to create predictive scenarios for the development of the technosphere.
