The diversity of social integration allows for many variations on breakdown theories of collective behavior. Durkheim's case for sociology was situated between at least two poles. In contrast with philosophy and other speculative approaches, he argued for a scientific approach to human behavior rooted in rigorous methods and empirical verification. Emile Durkheim's concern with social integration and solidarity was central in his first treatise on the division of labor in society, which makes three interrelated contributions. Egoism results when the bonds that normally connect people to each other and to social groups are unusually weak or ineffective. The stimulation and contagion deriving from the co-presence of many people in one time and place that Durkheim found in totemism and Le Bon found in crowds became a centerpiece of the collective behavior theory that prevailed in much of twentieth century American sociology.