A society has a dual organization when it is divided in two, with all of its members belonging either to one or to the other moiety (i.e. ‘half’). This widespread type of social organization is an elementary means of obtaining, in Leslie White’s words, ‘differentiation of structure, specialisation of function, and co-operation’. The general pattern allows, however, for considerable variation in forms assumed and functions or social role performed by moieties. Among the most elaborate examples of dual organization are those found in Aboriginal Australia, where it is commonly at work in the regulation of marriage, allocation of ritual responsibilities and classification of nature. As W. Lloyd Warner said of the Murngin division into the exogamous patrilineal moieties Duwa and Yiridja, ‘There is nothing in the whole universe — plant, animal, mineral, star, man, or culture — that has not a place in one of the two categories’.
In parts of Arnhem Land there are exoga-mous matrilineal moieties named Marawar and Rerwondji and non-exogamous, non-lineal ‘ceremonial’ moieties named Budal and Gwiyal as well as Duwa and Yiridja. Consequently each person belongs to three moieties, which cut across each other. In this region the most significant dichotomy is into patrilineal moieties. The initiated members of each have distinctive parts to play in such major religious cults as the Guna-bibi and the Yabuduruwa. Thus Duwa is said to ‘own’ the Gunabibi and Yiridja to ‘manage’ it,these roles being reversed in the Yabuduruwa. The arrangement expresses a division of responsibility: owners do most of the ritual dancing and most of the totemic images are of their moiety; but managers coordinate the programme and contribute labour, e.g. they make the dancing grounds and most of the objects used in the ritual. Were it not for the cooperation between moieties the cults could not be performed.
Although the dual organization of society is a manifestation of dualism, the latter can exist without it, as has been particularly emphasized by ^Rodney Needham in his studies, ultimately inspired by Robert Hertz, of handedness and symbolic classification. The Chinese philosophy of Yin and Yang is an example of classification without moieties. Husband, summer, etc. are classed as Yang and their ‘opposites’ — wife, winter, etc. — as Yin. The union of opposites yields wholeness — a conjugal pair, the year, etc. — just as the union of Duwa and Yiridja in Arnhem Land gives us society in its entirety. Needham thinks of a natural proclivity to binary classification (cf. A.L. Kroeber, who spoke of a psychological trend to dichotomize); such explanations root dualism, including its expression in moieties, in human nature. Hertz himself related it to the antithesis of sacred and profane, and saw the existence of moieties as ‘a reflection and a consequence of religious polarity’, but his explanation loses force when it is realized that this antithesis is among the more contestable legacies of the French sociological school.
Other prominent examples of dual organization are found in Southeast Asia, in South America and in North America, and there are African examples too. In some cases, village layout is based on dual organization. For example, Toraja houses each face north opposite the ‘spouse’, a barn which faces south. Each of these pairs stands in dual relationship to other houses, and, as is typical in Austronesia, these are embedded in a recursive framework of ever larger dualistic structures. In the Amazon, Ge peoples divide their villages into two halves, each represented by opposite moieties. The moieties are rivals, but exchange spouses in a system of reciprocity which characterizes indigenous South American social structure.
