 Having seen the main features of neo-Russellian approaches, let us turn to structured meaning accounts. The roots of these accounts can be traced to Rudolf Carnap [1947], and his notion of intensional isomorphism. David Lewis [1972] and Max Cresswell [1985] have worked out similar, detailed versions of the structured meanings approach, though there are important differences in their views. Cresswell’s [1985] version of the view will be discussed  here.[29]  Because our concern is with conceptions of structured propositions, there are many features of Cresswell [1985] that will not be discussed (e.g. Cresswell’s account of the semantics of verbs of propositional attitude).