Thus, we can distinguish two positions as far as the reference of the segmentary lineage structure is concerned. For some of the anthropologists mentioned above, it refers exclusively to a set of ideas, ideology, myth, or simply a set of notions. For others, it refers simultaneously to a set of notions and the pattern of social processes, the way in which the members of a society organize their activities. The first position faces a rather interesting problem: there is no denying that the set of notions called segmentary lineage structure exists; since it exists for the members of a society, it is their social reality. on the other hand, this set of notions is not manifested in social processes, in the organization of their activities. Since social processes, or the activities of the members of a society, exist equally undeniably and are also social reality, it is necessary to distinguish two different kinds of social reality which do not have to be directly related. Unless the observer is pre- pared to ascribe to both the same degree of fac- ticity or reality, he has to ascribe to one of them ontological priority. This is a problem we will be discussing at considerable length later on; in this context, it would be only a digression. However, it is important to note that the postulation of two levels or domains of social reality is directly necessitated by defining segmentary lineage structure as a set of ideas, ideology or myth.