English intonation is at the interface of phonetics and pragmatics. To describe the tunes you have to be able to analyse the changing pitch of the voice and the associated stress patterns, which is phonetics. To describe their meanings you have to be able to account for language use and contextual meaning, which is pragmatics. I feel confident about the phonetics, less so about the pragmatics.
Yesterday as I came up the escalator at Vauxhall tube station the man in front of me was carrying a medium-sized dog. He was complying with the instruction displayed at the foot of every escalator on the London Underground.
I've never figured out a really convincing explanation for why stressing "dogs" seems to encourage the interpretation "everyone must carry a dog", while stressing "carried" encourages the interpretation "if you have a dog, you must carry it".
Nor have I. I think this puzzle was first pointed out to me by Michael Halliday in about 1964; he didn’t have a satisfactory explanation, either.
If spoken, to carry the intended message this sentence must have the nuclear accent (“phrasal stress” for Liberman) on the verb:
- (ˈ)Dogs must be ˈcarried.
If you say it with the nucleus on Dogs, you encourage the interpretation “you can't use this facility unless you are carrying a dog", rightly characterized by Liberman as absurd:
- ˈDogs must be (ₒ)carried.
Please, pragmatics people, do go ahead and expatiate on the ‘implicit universally quantified agent’ by everyone and on the deontic modal must, because I don’t know how to, or at least not how to tie them up with the presence/absence of sentence accents.
In section 2.21 of my English Intonation, the section entitled Topic and Comment in the Tone chapter, I wrote
The topic is typically said with a non-falling tone (a dependent fall-rise or rise), the comment with a falling tone (a definitive fall).
OK, dogs is the topic, must be carried the comment; and we get the correct interpretation if we say
- \/Dogs | must be \carried.
- /Dogs | must be \carried.
— but this doesn’t explain why
- \Dogs must be ₒcarried.
- \Safety boots must be ₒworn.