Social evolutionism is a systematic approach to the study of social change, derived from social Darwinism and including the modern adherents of that theory in the USA. Social Darwinism applies the principles of the theory of evolution to social structure, justifying inequalities within society and between societies. Modern social evolutionism tends to be more descriptive than explanatory, but attempts to formulate evolutionary universals for society in general. Both social Darwinism and social evolutionism are materialist theories, the latter being used also to explain religious phenomena.