 The Circle’s leading protagonists differed in how they conceptualized this reflexive second-order inquiry that the linguistic turn had inaugurated. Nevertheless, they all agreed broadly that the ways of representing the world were largely determined by convention. A multitude of ideas hide behind this invocation of conventionality. One particularly radical one is the denial of the apodicity of all apriority, the denial of the claim that knowledge justified through reason alone represents truths that are unconditionally necessary. Another one is the imputation of agency in the construction of the logico-linguistic frameworks that make human cognition possible, the denial that conventionality could only mean acquiescence in tradition. Whether such ideas were followed by individual members of the Circle, however, depended on their own interests and influences. It is these often overlooked or misunderstood differences that hold the key to understanding the interplay of occasionally incompatible positions that make up Vienna Circle philosophy. (As can be seen from some of their internal disputes, moreover, these differences were also not always obvious to the protagonists themselves.)