The bonds between applied ethics and social science seem to become increasingly tight. This does not only manifest itself by social scientists and ethicists working together, but also by an increasing attention, from both sides, to the very nature of their cooperation. The debate on this topic has been ongoing for more than twenty years, but in the last years the discussion became more intense. However, one can doubt whether up until now the relevant questions have been sufficiently distinguished. Particularly the notion “empirical ethics” creates more confusion than clarification with regard to the different conceptual and methodological dimensions. The methodological debates show a wide spectrum of topics. This paper aims to make an inventory of the questions raised in the debate on the role of empirical research in (applied) ethics. We argue that there are at least five distinct groups of questions to be found in this debate, concerning: (1) the fact-value gap, (2) the notions of ‘discipline’ and ‘interdisciplinary’, (3) the nature of both ethics and social sciences, (4) the type of empirical research relevant for ethics, (5) the embeddedness of the individual researcher. The paper concludes with some suggestions for further debate.