 A solution of the first kind, following (Carnap 1947), is proposed in (Lewis 1972:182–6); the idea is that the meaning of a complex expression is not its intension, but rather a tree that exhibits the expression’s syntactic construction bottom-up, with each node in the tree decorated by an appropriate syntactic category label and semantic intension. But as Lewis says (p. 182), for non-compound lexical constituents, sameness of intension implies sameness of meaning. So although his approach will handle the water/H2O problem if we assume the term ‘H2O’ has structure that the term ‘water’ lacks, it will not without such an assumption. For the same reason, it cannot explain substitution-failure involving unstructured proper names, on the usual view (deriving from Kripke 1972) that identity of extension (at any world) for such names implies identity of intension. So we have no account of why admiring Cicero isn’t the same thing as admiring Tully.