In Qualitative Comparative Analysis (QCA) of social data, the generation of parsimonious explanatory equations is enhanced by the inclusion of ''logical configurations''. Even if this procedure proves to be very useful, it also raises various methodological issues. Among them, the tricky problem of ''contradictory simplifying assumptions'' has remained largely unexplored. Yet the careful control of this obstacle is crucial for any QCA to be successful, not only because contradictory assumptions are inducing wrong conclusions, but also because their resolution can generate most interesting results. Hence, our contribution aims at enlightening this difficulty, as well as designing an efficient way to overcome it. In this perspective, we start from data collected for a comparative research on ''the political feasibility of an unconditional basic income'' in six OECD countries (1980-2002). After having briefly stated the core elements of the research question, six operational variables are defined (section 1). On this basis, we conduct a Boolean analysis and comment the various 'feasibility scenarios' generated by the QCA 3.0 software (section 2). Starting from these first results, we identify contradictory simplifying assumptions used by the software, and discuss possible solutions to this problem. New results are then generated (section 3). In the conclusion, we shortly discuss the general implications of this methodological problem
data(Yamasaki)Vanderborght, Yannick and Yamasaki, Sakura 2004 Des cas logiques...contradictoires? Un piege de l'AQQC dejoue a travers l'etude de la faisabilite politique de l'Allocation Universelle, Revue Internationale de Politique Comparee, Vol.11, pp.51-66