What are the main variations in the constitutional control of the executive in 45 parliamentary democracies and how can these differences be accounted for? Four competing hypotheses, based on dichotomies, explain the degree of this control by means of contrasting institutional settings: consensus democracy versus majoritarian democracy, presidentialism versus parliamentarism, thick versus thin constitutionalism and established versus new democracies. These hypotheses are tested with the help of fuzzy-sets that allow for varying degrees of membership that go beyond the presence/absence suggested by these dichotomies. The necessary and sufficient conditions for constitutional control are specified with the help of this new methodology. The fuzzy-set analysis shows that the degree of constitutional control can be explained solely by a specific combination of institutional conditions stemming from the four dichotomies, and not by one single dimension. This constellation remains hidden for the traditional correlational techniques like regression. Hence, the fuzzy-set logic presents a promising new tool for comparativists that can be used to reveal causalities.