Locating Qualitative Comparative Analysis (QCA), Set-Theoretic Methods (STMs) and Configurational Comparative Methods (CCMs) in the Methodological Logical Space: A First Systematic Attempt

Initially, in the field of QCA/STMs/CCMs, there was only one technique (crisp-set QCA), whereas now several techniques have been developed: its close cousins mvQCA, fsQCA and tQCA, but also other neighbours such as CNA and NCA. In parallel, other forms of multiple cross-case comparisons have developed, such as sequence elaboration, comparative-historical analysis; besides, some other techniques are also following some sort of configurational thinking (e.g. APES, AQUAD, some other non-QCA Boolean analyses, etc.). In addition, some QCA applications have developed in the direction of larger-n designs, including some probabilistic reasoning that is shared by some statistical methods; conversely, some other QCA applications are pushing towards the small-n spectrum and establishing links with single-case methods focused on causal mechanisms (e.g. process tracing). Given this plurality of developments, it becomes increasingly difficult to precisely locate QCA, STMs and CCMs in the methodological space. Are these three labels equivalent? Do they simply belong to a well-defined category of ‘Set-Theoretical Approaches’ (STA) easily defined as being opposed to correlation-based statistical approaches (as argued by Schneider & Wagemann, 2012: 10)? Do they belong to the realm of “qualitative” methods (to be delineated), or do they constitute a broad ad hoc category that cannot be considered as belonging to either the “qualitative” or “quantitative” spheres? In this paper, we first survey the various answers that have been given to the question: “where to locate QCA, STMs & CCMs?”. Then we attempt to take a broader and more systematic view and, based on an examination of the definitional properties of QCA, STMs & CCMs, we propose some alternative views, adopting taxonomy, typology and set-theory logics, so as to map QCA, STMs & CCMs more precisely – and in a more dynamic way – in the logical space of methods.