The concept of  distributed and situational cognition is nowadays widely discussed in cognitive sciences and other fields of knowledge. It states that the forming of cognitive result is due not only to the operations of individual intelligence but mainly to its interaction with the environment, other individuals and material objects. Two principal problems of such an approach are presented by the randomness of cognitive system borders as well as insufficient attention to the nature and the reasons of situational environment explaining cognitive processes existence in «natural conditions». To solve the former it is proposed to pay the most attention not to cognition but to the process of problem solving. To solve the latter it is possible to use functional and evolutional arguments.