In Sperber and Wilson’s Relevance (ISBN9780631198789) they quote the following in discussing the idea of mutual knowledge:
On Wednesday morning Ann and Bob read the early edition of the newspaper, and they discuss the fact that its says that A Day at the Races is showing that night at the Roxy. When the late edition arrives, Bob reads the movie section, notes that the film has been corrected to Monkey Business, and circles it with his red pen. Later, Ann picks up the late edition, notes the correction, and recognises Bob’s circle around it. She also realises that Bob has no way of knowing that she has seen the late edition. Later that day Ann sees Bob and asks, ‘Have you seen the movie showing at the Roxy tonight?’ (Clark and Marshall 1981: 13)
Here are the facts in the order of action:
- they both saw the morning edition of the newspaper
- they have discussed the movie showing that night
- Bob knows the movie has changed and circled it in the late edition newspaper
- Ann saw the circled changed movie name in Bob’s absence
- Ann knows Bob does not know she saw the late edition newspaper in which Bob circled the changed title being screened
- She asks, ‘Have you seen the movie showing at the Roxy tonight?’
To be honest, if Ann had been a good communicator would she not just have added an extra statement, ‘I saw the movie showing now is Monkey Business. Have you seen it?’
Was there any reason not to say she knows the newspaper listing has been corrected? Is there a reason why Ann decided not to acknowledge her own knowledge of the change with a simple statement?
The idea that sparsity of language equates to efficiency of language is wrong. Perhaps in poetry economy is valued. But in normal everyday communication such checks can be done without much disturbance to efficiency. In fact adding the extra statement may help in avoiding any misunderstanding.
And why would not Bob confirm with her that they are talking about the same movie? Why not just reply, ‘You mean Monkey Business? No, I haven’t’. That would save Ann, Bob, the authors – Sperber and Wilson – and us readers a lot of grief and pain.