 The difficulty with this argument, as a number of writers have pointed out (see, e.g., Yourgrau 1987; Gaskin 1997: 153 n. 17; Künne 2003: 133–41), and the place where the identity theorist is likely to raise a cavil, lies in the first assumption on which it depends. Davidson calls this assumption “reasonable”, but it has been widely questioned. It states “that logically equivalent singular terms have the same reference”. But intuitively, the ideas of logical equivalence and reference seem to be quite distinct, indeed to have, as such, little to do with one another, so that it would be odd if there were some a priori reason why the assumption had to hold. And it is not difficult to think of apparent counterexamples: the sentence “It is raining” is logically equivalent to the sentence “It is raining and (either Pluto is larger than Mercury or it is not the case that Pluto is larger than Mercury)”, but the latter sentence seems to carry a referential payload that the former does not. Of course, if declarative sentences refer to truth-values, as Frege thought, then the two sentences will indeed be co-referential, but to assume that sentences refer to truth-values would be question-begging in the context of an argument designed to establish that all true sentences refer to the same thing.