In the paper, a philosophical and methodological analysis of the evolution of cybernetics in the context of the development of scientific rationality is carried out. The evolution of cybernetics is represented as a movement from the methodology of “observable systems” and to the methodology of “observing systems” and to the methodology of self-developing reflexive-active environments. Special attention is paid to the formation of a new promising direction for post-non-classical cybernetics of self-developing poly-subject environments, which, given the correlation with previous stages (...) of cybernetics development, we define as thirdorder cybernetics. The analysis of the basics of the formation of third-order cybernetics was carried out with consideration of interrelated aspects: philosophical, methodological, theoretical, and methodical. We also provide model of self-developing poly-subject environments as well as a system of ontologies, defining the mechanisms of functioning of such self-organizing poly-subject environments and active elements that organize the communication space. The ontology system also makes it possible to integrate cybernetics of the first, second, and third order. Some sociohumanitarian trends in the development of cybernetics are considered: from an external observer to a distributed observer; from monodisciplinary to transdisciplinary approaches; from activity approach to subject-activity one, and further to subject-oriented approach; from information to active knowledge; from ethics of goals to ethics of strategic subjects. Potential opportunities for using third-order cybernetics are described, in order to improve the quality of solving a number of important scientific and practical problems of controlling social systems. Information is provided on the directions of approbation of a third-order cybernetics concept for improving state administration, based on a system of distributed situational centers, and there is its approbation at international scientific conferences. (shrink)