The scope of interests in the area of information systems (IS) has focused mainly on technological aspects so far. If the human component were taken into account, it has been analyzed from the level of an individual. So have all new concepts of rationality. This chapter argues that collective behavior, which is a basic determinant of the global IS dynamics, does not proceed in a planned manner, but is adaptive and follows certain patterns found in nature. It follows that this behavior can be expressed in a model form, which enables to structure it. A model exemplification of a global information system is a modern, electronic, stock exchange. The identification of quantitative attributes of a social subsystem can provide substantial theoretical and methodological premises for the extension of the optimizing and individualistic notion of rationality by the social and adaptive aspects.