Notes on Carnap's replies to essays by other philosophers concerning his views on language, modal logic, and semantics.

Surpisingly stable aspect of Carnap's philosophy, unchanged except by moderation of terminology since 1928. The theses of realism lack cognitive content (originally, are meaningless).

Carnap uses the collective "we" in talking about these view, which I take to indicate his belief in there having been a concensus at that time in the Schlick (Vienna) circle. He refers to the first edition of "Pseudoproblems in Philosophy", published in 1928 (in german) as documenting the position.

The following claims are held to lack "cognitive content".

1. The assertion of the reality of the external world, and its various denials, including solipsism various kinds of idealism.
2. The assertion of the reality of other minds and its denial.
3. The assertion of the existence of abstract entities and its denial.

Though the claims lack cognitive content, there are closely related practical questions about choice of language which are of importance. The list of languages mentioned here differs somewhat from the languages mentioned earlier in Schilpp volume:

• phenomenalistic language
• the thing language
• physical language
• dualistic language

Carnap considered this problem not long before the Schilpp volume and wrote the paper `Empiricism Semantics and Ontology' Carnap50 (in second edition of meaning and necessity). He refers to that paper, but provides an example illustrating his position. His position is explained through the distinction between internal and external questions.

These are ontological questions expressed in a language whose semantics has been defined, and they are settled by the semantic rules for the language.

These are ontological question asked out of context, i.e. in some language which has no definite semantics (often in the context of defining some language). These have no cognitive content. The question of legitimacy of a language definition which employs such entities is to be resolved not by answering the external question, but on pragmatic considerations.

Carnap describes a couple of simple languages, and gives some internal and external questions in relation the languages and states his position in relation to them and gives some suggestions on the pragmatic considerations which might be considered.