 For all the technical apparatus, Carnap later acknowledged that “the investigation of philosophical problems was originally the main reason for the development of syntax” (Carnap 1963a: 55), and the final Part V of the book is devoted to these. The focus, however, is on the “syntax” idea itself, not on the other main idea, the principle of tolerance. There is a simple reason for this: Part V was almost entirely written before Carnap arrived at the principle of tolerance in late 1932, and when the book went to the publisher it had to be cut (the definition of “analyticity” for Language II (§ 34d), for instance, was not even included in the original book, only in the 1937 English translation). And Part V is devoted to a sustained argument for sticking to the “formal mode of speech” and avoiding the “material mode of speech” unless it is translatable into the formal mode. So it is hardly surprising that philosophers (see for instance Woleński 2003) took this to be the book’s main philosophical point and thought Carnap had left it behind after the embrace of semantics in 1935. 