The "brain drain/brain gain" debate has been going on for the past 40 years, with irresolvable theoretical disputes and unenforceable policy recommendations that economists commonly ascribe to the lack of reliable empirical data. The recent report of the World Bank, "International migration, remittances and the brain drain", documents the quantitative acceleration and the growing polarisation of the international flows of high-skilled workers over the last decade. In this article the author takes issue with the view that this database could help settle the controversy, on the grounds that the problem lies less in the absence of empirical data than in the conceptual framework of the underlying models, which are static, retain nation states as the pertinent space of analysis, and assume labour demand to be exogenous. Starting from opposite premises, the author suggests distinguishing between two types of migration flows. One, potentially reversible, concerns the tradable, for-profit productive occupations, the location of which are directly controlled by capital's global strategies. The other, self-sustaining, refers to the non-traded, not-for profit occupations which cater for the reproduction of the labour force, under the budgetary constraints laid upon states by their involvement in competition to attract capital flows. (Contains 1 figure and 22 notes.)