By this test, I regret to say, social anthropology reveals itself as not yet a formed science.''" In addition to identifying abstract relationships between social structures, Radcliffe-Brown argued for the importance of the notion of a 'total social structure', which is the sum total of social relations in a given social unit of analysis during a given period. The identification of 'functions' of social practices was supposed to be relative to this total social structure. Lévi-Strauss saw social structure as a model. Within his research, Radcliffe-Brown focused on so-called "primitive" societies. He believed kinship played a large role in these societies, and that patrilineages, clans, tribes and units all relate to kinship rules in society and are essential in political organization. Radcliffe-Brown claimed that all research on social structure is based on observations, what anthropologists see and hear about individual peoples. Radcliffe-Brown also argued that the study of social structure encompassed culture, therefore there is no need for a separate field dedicated to culture. Evolutionism, diffusionism, and the role of social anthropology A major view in the study of tribal societies had been that all societies follow a unilineal path ('evolutionism'), and that therefore 'primitive' societies could be understood as earlier stages along that path; conversely, 'modern' societies contained vestiges of older forms. Another view was that social practices tend to develop only once, and that therefore commonalities and differences between societies could be explained by a historical reconstruction of the interaction between societies ('diffusionism'). According to both of these views, the proper way to explain differences between tribal societies and modern ones was historical reconstruction. Radcliffe-Brown rejected both of these views because of the untestable nature of historical reconstructions. Instead, he argued for the use of the comparative method to find regularities in human societies and thereby build up a genuinely scientific knowledge of social life. "For social anthropology the task is to formulate and validate statements about the conditions of existence of social systems (laws of social statics) and the regularities that are observable in social change (laws of social dynamics). This can only be done by the systematic use of the comparative method, and the only justification of that method is the expectation that it will provide us with results of this kind, or, as Boas stated it, will provide us with knowledge of the laws of social development. It will be only in an integrated and