Description: Achievement of the personal interest of person, which makes decision (ОПР), in relation to understanding of importance of the certain phenomenon of nature and its change at times, is provided by working off by it methodological bases, - as an aggregate of receptions of sequence of researches at direction of recognition of the certain real phenomenon of nature, - after her subjective vision. From the point of view of purpose of the personal interest of ОПР any by an object and display of nature, not depending on that when and by whom created, when and what caused, objectively exist in the wild and function to displays of their subjective vision of ОПР, that is why they fold maintenance of the phenomena of nature for ОПР. Separation of some integrity of ОПР for further consideration - folds maintenance of the system. Subjective vision of list of factors and their nature provides the exposure of natural maintenance of environment, the system functions in which, and the method of exposure of the most substantial factors allows to define the model of the system. In time, when factors form a certain environment or stochastically indefinite environment, ОПР has warrants to assert that it must examine the model of the simple system, and a research purpose can be formulated as recommendations in relation to a management by the process of functioning of the simple system at times. In time, when factors form an unclear unstochastically indefinite environment, ОПР has warrants to assert that it is necessary to form the model of the difficult system, and a research purpose can be formulated as recommendations in relation to influence on forming of own conduct of purposeful development of process of functioning of the difficult system at times.
Keywords: unstochastic, unclearness, vagueness, environment, making decision