The debate between J. Habermas and N. Luhmann on the "program of a theory of society" has stimulated much concern among sociologists because of its intention to grasp the society in its totality against the main trend in sociology to work without society. Some main points of controversy such as "constitution of meaning, " "discourse" and the "unity of theory and practice" are discussed here. It seems that the understanding of "subject" divides the two models of "Gesellschaftstheorie." Luhmann's notion of subject is more convincing and supported by paradigms of contemporary philosophical studies. But once applied to the everyday social life, his system theory seems to bring hopeless heteronomy and powerlessness in individuals confronted with the "world-complexity" and "system rationality."