 Secondly, the interesting cases of RI do not involve a shift from an impoverished point of view to an improved one — whether this is seen in epistemic terms (which Geach disputes — Geach, (1973)) or in purely logical terms. We do not affirm that old Oscar and young Oscar, for example, are the same dog on the grounds that there is an ideology with respect to which old Oscar and young Oscar are indistinguishable. Such an ideology would be incapable of describing any change in Oscar. It is true that the same dog relation determines a set of predicates that do not discriminate between the members of certain pairs of dogs — the dogs in the photographs mentioned earlier, for example. And it is true that these predicates determine a sublanguage in which the same dog relation is a congruence, i.e., no predicate of the sublanguage distinguishes \(x\) from \(y\), if \(x\) and \(y\) are the same dog. But the very sense of such statements as that old Oscar and young Oscar are the same dog requires a language in which a change in Oscar is expressible. We are talking, after all, about old Oscar and young Oscar. If we take seriously the idea that change involves the application of incompatible predicates, then the sublanguage cannot express the contrast between old Oscar and young Oscar.