CHANGES IN SOCIAL STRUCTURE AND NEW DEVELOPMENTS IN AMERICAN SOCIOLOGY Deng Fang (129) History of American sociology has shown that it is very important for sociologists to distinguish social problems that derive from changes in social structure. A major social problem in the U.S. today is an asymmetric structure of social responsibility. The focus of American sociology is shifting from the study of how social system influences individual actions to the study of how individual purposive actions are combined into behavior of a social system.