From the perspective of economic science social capital opened space for the analysis of social structure, social norms and institutions i.e. for the analysis of the long neglected influence of socio-cultural factors on economic changes and processes. Trying to explain how social structures emerge on the basis of individual optimization, i.e. to explain them by the logic of rational choice, economic science widened its analytical domain. The explanatory scope of the basic neoclassical principles has been considerably widened to incorporate what has previously been considered to be the analytical terrain of other social sciences. This process has been labeled in scientific circles as 'colonisation' of social sciences, or economics 'imperialism'. The goal of this paper is to determine the implications of these changes for the relation between economic science and other social sciences.