Pär Segerdahl, Language Use, Ch.8, "Rationality as a Basis for Language Use"

Grice's cooperative maxims and conception of the rational norms governing conversation are meant to explain our ordinary practices of understanding sentences; but the maxims and conversational norms themselves depend on those very practices for their intelligibility. For example, the notion of cooperation requires some particular, concrete practice (like work in a repair shop) in order to have any content. It doesn't make sense to say that there is some general, practice-independent notion of cooperativeness that governs our understanding of speakers' utterances.