Unnoticed by economic geography for fifteen years, Boschma’s (2005) proximity paper conflates two different causal logics: regularity and substantive interpretation. The former is dominant in variable-based methods, the latter in case-based methods. Using the proximities approach as an example, this paper explains the differences between both logics. A QCA (Qualitative Comparative Analysis) study on simulated data demonstrates how case-based methods use substantive interpretation for causal inference. QCA is an important innovation in case-based methods that, thus far, economic geography has largely missed. QCA challenges the search for causal effects of individual causes and presents configurational causality as a compelling alternative.