Farming Family typical of Japanese tradition was stem family. It had the system of patriarch and primogeniture. The eldest son continued to live after marriage in the same house with his parents. The family continues over generations. This was the Japanese family, ‘ie’;
‘In some case, younger sons established branch families (called bunke=分家) . Main family they left was called ‘honke’(本家). Honke and bunke keep intimate cooperative relation in daily lives from generation to generation.
　Ariga established theory of “ie“ and mura(Japanese village community) in the sociological study of Japanese rural society.
　In principal work, he insisted as follows.
　There were two types of rural village. ① Village developed by one powerful stem family. There appeared the group consisting of main family and branch families (Douzok=同族)., including the relation of master and servant ②Village developed by plural families in equal status.
　Then, there were two types of relation among “ie”. One is vertical(upper ‐lower) one and another is horizontal (equal)one. The former relation appeared as the group of blood relatives’(called douzoku(同族), consisting of main family and branch family. Second type also easily changed to the honke-bunke relation, if there appeared vertical relation. In Japan, Generally, vertical relation become to such kindred -like or patron -client relation. The upper had legitimacy of “publicness”, the lower’s activities were private, and the person on upper status initiate the social relation.
　The cooperation of Japanese become stronger in vertical relation, and weaker in horizontal one. This is the nationality (national characteristics) of Japan proper, Ariga insisted.
　After the World Ⅱ, Ariga did not strongly insisted Japanese nationality . His theory concentrate on the study of ‘ie’ .He argued ie and honke-bunke group(同族) were originated to get life-security of group members. This was indispensable in the lacking circumstances of political assistance for life- security.
　Late in life, Ariga developed the thought of integrate cultural sphere of nation. On behalf of insisting the persistence of cultural tradition in his young days, he thought that this sphere of japan had been gradually changed through the creative activities of Japanese and exchanging with other cultures outside, but on the base of national tradition, Japanese ‘ie’ culture also is changing.