Rudolf Carnap"s many attempts, throughout the course of his scientific career, to determine a concept of logical truth or analyticity, provide a case study in explication. Indeed, it was perhaps the difficulty in nailing down just this notion that first led to the conception of explication. Thus it may be seen as a paradigm case. However, Carnap"s work on the problem of the nature of logical truth is of course also of systematic and theoretical importance, as it provides us with a record of the major attempts to solve a fundamental philosophical problem — Carnap having been its leading investigator — and one which still remains very much in need of clarification.