I recently had a conversation with someone on line about a similarly structured sentence,
John and Billy’s dog ran away last night.
Seems easy enough. No problems here. Yep. Whoa….wait. Does that dog belong to John and Billy? Or is it saying that John had a dog and Billy had a dog and they both ran away last night (yes, to shack up in Vegas!). If I had ONLY that context given to me in a survey, written that exact way, I would say the former. However, if there was another example written thusly,
John AND Billy’s dog ran away last night. (CAPS = stress)
I would have to say that there are two separate entities (John has a dog and Billy has a dog, and the two ran away). Sure, we can use the conjunction and to convey that the subjects are conjoined in some sense; there’s no doubt about that. But my argument is that the conjunction and could also be used, and is used quite often in spoken speech, to separate even the same entities which were once bound. How? Well, by this stress on and in the second example.
Stress can do many things in any given utterance.
Here, we know in each case that the speaker promises (to do) something, but the second one with added stress gives that extra “comfort” that the said promise will be seen to fruition. The first one doesn’t say anything about the person’s intention to uphold his promise.
If Sam comes to the party, he’ll get trashed.
IF Sam comes to the party, he’ll get trashed.
Again, the same thing in these two sentences. The first one is very colloquial in speech, “by the way, if Sam shows up, that fucker will get trashed.” The second implies that Sam doesn’t really show up to these parties often, so chances are, don’t hold your breath. Sam has probably even said he’ll show up to a few past parties and never did.
Now, this problem with the conjunction. Notice when people want to stress separate events on top of other events when speaking about their schedule, for example.
Dude, are you kidding me? Time? Dude, check it: I’ve got to send my dog to the groomer, wash the car, get lunch for Sara, deliver to her, pick up the dog from the groomer’s…I’m slammed. AND, on top of that, I have to work the night shift.
The working the night shift is separated but meant to add to the events of the day. The phrase, on top of that is optional, but is usually said in that rhetorical style. So the events are hierarchical (with or without the on top of that phrase) because the hearer automatically assumes an additional event to the previous event(s). The same is true for John AND Billy’s dog running away. Sure, without the stress it can be construed as ambiguous, but the stress adds that extra “umph” to the understanding that both of their dogs ran away. Now, this clearly seems to be related to the omission of the adjective both used in the sense of relating two things in conjunction. Basically, since both is omitted and the and is not stressed, it produces the said ambiguity (but really leans more toward meaning that the dog belonged to both John and Billy–I agree).
I hope that this makes sense and is, to some extent, accurate. The point is, the same sentence can have different interpretations because of the stress on the conjunction. Syntax may want to show or prove otherwise, but we need to look beyond using syntax to interpret meaning.