Conversational Pragmatics and Frictionless Solids

I think they are mentioned in Chapman's Grice. Those frictionless solids. I should have to revise. The idea is that all this abstract talk of conversation, cooperative principle, maxim, descriptive adequacy, is ... well, theory. Grice says, "it may still be of some use. Cfr. frictionless solids". I.e. "even if shown that nobody was ever seen to follow the cooperative principle!" (or words).