Professor Giddings develops an interesting theory of the dualism in social structures. Civilization is marked by the contemporaneous existence of public and private associations. Civilized society affords four main sets of dualistic associations: political, juristic, economic, and cultural. In the political field there are private political parties and the public association, namely, the government, or the political party in power. Among juristic associations there are the privately-organized vigilance committees and the public associations, such as the police, the courts, the prisons. In the realm of economics there are private individual entrepreneurs, partnerships, corporations; and on the other hand, there are the governmentally-owned railroads, postal service, the water systems, the coinage systems. In regard to cultural associations we may note the privately endowed universities and state universities, privately organized churches and state churches, private charities and public charities. This dualism in social structure is supported by Professor Giddings on the grounds that private associations are needed for purposes of initiation, experimentation, and stimulation; and the public associations serve the useful purposes of regulation and maintenance of balance among various contending factors. The highest test of social organization is the development of social personality. An efficient social organization is one which makes its members “more rational, more sympathetic, with an ever-broadening consciousness of kind.”[XXII-44] In recent works Professor Giddings has developed the concept of pluralistic behavior. “Any one or any combination of behavior inciting stimuli may on occasion be reacted to by more than one individual.”[XXII-45] The character of pluralistic reactions, whether similar or dissimilar, simultaneous or not, equal or unequal, is determined by two variables: (1) the strength of the stimulation; (2) the similarity or dissimilarity of the reacting mechanisms.[XXII-46] Thus Professor Giddings considers pluralistic behavior the subject matter of the psychology of society, or sociology.