In the social sciences, methodological individualism is a method for explaining social phenomena strictly in terms of the decisions of individuals, each being moved by their own personal motivations. In contrast, explanations of social phenomena which assume that cause and effect acts upon whole classes or groups are deemed illusory, and thus rejected according to this approach. Or to put it another way, only group dynamics which can be explained in terms of individual subjective motivations are considered valid. With its bottom-up micro-level approach, methodological individualism is often contrasted with methodological holism,[1] a top-down macro-level approach, and methodological pluralism.[2]