Peter Railton´s excellent discussion of Gricean value-implicature of factual language, in "Moral Factualism".

by JLS
--- for the GC

ANYONE WHO IS MINIMALLY INTERESTED IN fact-value language distinctions alla Blackburn will have to engage in the type of argumenation as proposed by Railton. Factive language implicates valuing. This however allows one to remain a moral factualist. For, after all, an implicature is ALWAYS cancellable!