Functionalism

Map of the European Union (Photo: www.delalb.ec.europa.eu/en/about_the_eu/eu_sy..)
An early theory of European integration that claims that functions of government tend gradually and unceasingly to be transferred from the national to the supra-national level because they cannot adequately be undertaken at national level. This is due to the smallness of size, lower economies of scale, inefficiency etc. which exists at national level.
This theory tends to exaggerate the importance of size and underestimate the importance of democratic accountability in giving legitimacy and authority to states.