During the first half of the twentieth century, Franz Boas contributed to a profound paradigm shift in the social sciences: the understanding that cultures are distinctive, dynamic, and fluid and there is no biological basis to explain extant racial categories. Boas greatest contribution to both science and society was the way he used empirical evidence and the scientific method to challenge ideas of racial superiority and inferiority by designing research to demonstrate that racism, the environment, and the history of specific cultures explained difference and diversity. This challenged the prevailing view that certain cultural groups were organized in racial hierarchies determined by a state of savagery, barbarianism, or civilization. Boas showed how cultures were not bound by racial categories and argued that history and the environment, as well as the diffusion of customs, beliefs, and language influenced specific cultures in different ways.