 Carnap argues in Meaning and Necessity (especially §30) that his method of extension and intension is an improvement over Frege’s method of reference and sense, because it preserves the extension and intension of a linguistic expression across contexts (i.e., regardless of whether they are extensional or intensional contexts), while Frege’s method does not. Before Michael Dummett’s work on Frege, Carnap’s detailed critical engagement with Frege’s theory of sense and reference in this book probably did more to establish Frege as a classic of analytic philosophy than any other single impulse. Not only Church, but many others were inspired not only to reconstruct Frege’s original view in a more rigorous way, but to do so in the light of Carnap’s challenge and his critique of those views from a modern point of view. Carnap’s intensional semantics is discussed in more detail in the supplement  Semantics (Section 1).