Philosophers -- especially Witters! -- use 'language' too broadly. I dunno 'bout Carnap! (But I have an appointment at the Carnap Corner with someone).
In a paragraph of his "Meaning Revisited", Grice follows a strategy that Bennett will follow in his "Language". What Grice is up to is how to provide a 'rational reconstruction' and evolutionary at that, of what 'language' should be for Grice and for a Griceian.
"In some cases, the artificial communication devices might have certain other
features too, over and above the one of being artificial: they might, for example, involve a finite number of fundamental, focal, elementary, root devices, and a finite set of modes or forms of combination (combinatory operations, if you like) which are capable of being used over and over again. In these cases, the creatures will have, or be near to having, what some people thought to be characteristic of a language: namely: a communication system with a finite set of initial devices, together with semantic provisions for them, and a finite set of different syntactic operations or combinations, and an understanding of what the functions of those modes of combination are. As a result, they can generate an INFINITE number of sentences or complex communication devices, together with a correspondingly infinite set of things to be communicated, as it were. So, by proceeding in this teleological kind of way, we seem to have provided
some provided some rationale for the kind of characterization of speaker's
meaning which I went for long ago, and also for the characterization of various kinds of communication
systems, culminating in things which have features which are ordinarily supposed (more or less correctly, I would imagine) to be the features of a fully developed