The different branches or schools of thought in sociology include functionalism, conflict theory, symbolic interactionism, social exchange theory and formalism. Of these, the three main branches are functionalism, symbolic interactionism and conflict theory.
Functionalism is the top-down analysis of society as a complex of interrelated and interdependent parts. One of the key figures in the development of this branch of sociology was Talcott Parsons, who claimed that a society must fulfill the criteria of adaptation to the environment, goal attainment by striving toward a collective vision, integration by mediating conflicts between individuals, and pattern maintenance as in the transmission and survival of social values. Since each of these criteria was integral to a society's survival, Parsons reasoned that all parts of a functioning society must be functional toward fulfilling these criteria.
Symbolic interactionism focuses far more on the individuals within society, analyzing the symbols they use and the ways in which they interact. One of the key figures in this branch of sociology was Max Weber, who stated that behavior is determined by individual and subjective interpretations of meaning — not so much by functional necessity.
Conflict theory, meanwhile, centers upon the struggles within society — especially class struggles between rich and poor. Growing out of the works of Karl Marx, the conflict branch of sociology is often proactive in advocating social change.