Abstract
Liberalism and deliberative democracy constitute two contradictory theoretical paradigms of contemporary politics. This contradiction has an impact on the ways of assessing the democratic qualities of the European Union (EU). This article traces back the tenets of both approaches to concepts of ‘interest’ and ‘reason’ and arrives at two sets of democratic thresholds that European institutions should meet. Since both rationales are incompatible, they can hardly be combined in empirical research. This explains why the debate on the democratic quality of the EU has so far led to a mere co‐existence of various normative theoretical approaches. The article concludes by sketching out general guidelines as to how to translate both normative paradigms into empirical research on the EU.