Grice on 'informativeness' in the light of Carnap/Bar-Hillel's pragmatics

--- by JLS
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WE ARE DISCUSSING (with R. B. Jones) THE OVERLAP in the conceptions of pragmatics in Carnap and Grice. When it comes to what Grice, echoing Kant, jocularly, calls "Quantitas", what we should really be concerned with is that Carnap/Bar-Hillel researched on, within the realm of pragmatics. As per this quote in the wiki for Bar-Hillel:

"Bar-Hillel was a major disciple of Rudolf
Carnap, whose Logical Syntax of Language much
influenced him. He began a correspondence with
Carnap in the 1940s, which led to a 1950 postdoc
under Carnap at the University of Chicago, and
to his collaborating on Carnap's 1952 An Outline
of the Theory of Semantic Information."

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Carnap holds, like Grice, a 'theoretical approach' to pragmatics. Pragmatics is built upon 'theoretical concepts' of which Carnap (as would Grice) mentions three: 'assertion', 'utterance' and 'belief'.

But consider 'semantic information'. Why the focus on 'semantic'? How IS information to be measured? And how does it impinge on 'pragmatic' factors.

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Consider the 'pragmatic' (defeasible) inference:

"Some students are Polish"
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"Not all students are Polish".

---- This seems to delve on the 'semantic' informativeness. Why bother to assert a weaker assertion when a stronger one is available? Yet his factors are 'pragmatic': they do deal with 'semantic information' but they do not concern the 'intension' or meaning or sense of the utterance-types involved. Etc.