Action theory refers to the variety of analytical-empirical systems of statements in the social sciences that aim to describe individual actions and use them as a starting point for explaining social phenomena. Methodological individualism, as a possible fundamental principle of social scientific explanation, does not limit itself to the view that institutions and collective phenomena are merely aggregations; it does not deny either the social character of individual actions or the existence of independent collective phenomena at the system level. The most prominent dichotomous typology formed within action theory differentiates between rational and normatively oriented actions. The former is represented by the homo oeconomicus, while the latter is represented by the homo sociologicus. In economic theory, various elaborations of the concept of bounded rationality have shaped the discussion since Simon.