The book examines the theoretical status and methodological foundations of systems science. The characteristics of the forms and stages of formation and development of the basic ideas of systems science are given. The relationship between the principle of consistency and the principle of connection, the principle of causality, and the principles of organization and development is analyzed. The categorical series of the systems approach is considered against the background of the concepts of structure, function, probability, information and other concepts of a general scientific nature. The practical significance of the principle of consistency for solving problems of social management is revealed. As a result, a unique model of the formation and development of general science of systems is substantiated, and principles of its effective application in various fields of knowledge and human activity are developed.