 In order to assess the challenge these philosophical applications pose for the traditional account, we need to resolve issues that are under current philosophical debate. Some of the issues are the following. (i) It is plain that some violations of Conservativeness are illegitimate: one cannot make it true by a stipulation that, e.g., Mercury is larger than Venus. Now, if a philosophical application requires some violations of Conservativeness to be legitimate, we need an account of the distinction between the two sorts of cases: the legitimate violations of Conservativeness and the non-legitimate ones. And we need to understand what it is that renders the one legitimate, but not the other. (ii) A similar issue arises for Eliminability. It would appear that not any old theory can be an implicit definition of a term \(X\). (The theory might contain only tautologies.) If so, then again we need a demarcation of theories that can serve to implicitly define a term from those that cannot. And we need a rationale for the distinction. (iii) The philosophical applications rest crucially on the idea that an implicit definition fixes the meaning of the defined term. We need therefore an account of what this meaning is, and how the implicit definition fixes it. Under the traditional account, formulas containing the defined term can be seen as acquiring their meaning from the formulas of the ground language. (In view of the primacy of the sentential, this fixes the meaning of the defined term.) But this move is not available under a liberalized conception of implicit definition. How, then, should we think of the meaning of a formula under the envisioned departure from the traditional account? (iv) Even if the previous three issues are addressed satisfactorily, an important concern remains. Suppose we allow that a theory \(T\), say, of physics can stipulatively define its theoretical terms, and that it endows the terms with particular meanings. The question remains whether the meanings thus endowed are identical to (or similar enough to) the meanings the theoretical terms have in their actual uses in physics. This question must be answered positively if implicit definitions are to serve their philosophical function. The aim of invoking implicit definitions is to account for the rationality, or the aprioricity, or the analyticity of our ordinary judgments, not of some extraordinary judgments that are somehow assigned to ordinary signs.