Picking up your litter is dangerous

Right, here's the other post I promised yesterday. The other litter-related sign I saw said this:

Picking up your litter puts road workers' lives at risk. 

This time, it's not ellipsis that causes the ambiguity, as it was in my previous post. Rather, it's a choice between two people who are doing the picking up:

You picking up your litter puts road workers' lives at risk.
Them [road workers] picking up your litter puts road workers' lives at risk.

And also unlike yesterday, it's clear which one is meant here. There's not any obvious way that you picking up your own litter puts anyone else's life at risk; it's a good thing and you should do it. On the other hand, a road worker having to dash out into the traffic to pick up your crisp packet is a danger to that person.

This is another example of ambiguity in the reference of a pronoun, just like yesterday. But in this case, it's the invisible pronoun that linguists call 'PRO' (pronounced 'big pro', to distinguish it from 'little pro', which is a similar but different invisible pronoun). It's the subject of the clause picking up your litter, which has a gerund form of the verb in it (the -ing form). When you have that, you can have a subject which isn't pronounced (PRO) and gets its meaning (reference) from something else in the surrounding discourse context.

If something is the topic of the sentence, that's likely to be what's assumed to be the meaning of PRO, but other things are also relevant, like where the other possible referents are in the sentence, and what kinds of things they are (e.g. litter is not a likely candidate to be picking itself up here, for many reasons!). Shameless plug: you can read some actual research by me and my colleague Vikki (mostly her) here, on a related subject, and we cite a load of previous research that you can look up if you like.

In my sign, the road workers are the topic (well, their lives are, but you also need to be an animate creature to pick up litter). 'You', the reader, are also an option, because your litter is in there too. It's also closer in the sentence to the PRO that needs a meaning, which counts for something, but a strong combination of the road workers being both the topic and the more sensible meaning ensures that no one would read it and think that PRO meant you. Except me. I thought that. That's why I wrote this whole blog post about it.

Take your litter home with them

I was driven across the country on Saturday, all the way from Sidmouth in Devon to Margate in Kent. On the way I noticed two signs about litter on the roads, both of which are pleasingly ambiguous. I couldn't take a photo as I whizzed by, but the first one said this:

Take your litter home with you.
Others do. 

The ambiguity is between what linguists call a 'strict identity' and a 'sloppy identity' reading of the missing bit of the second sentence. Others do stands for either Other people take your litter home with them or Other people take their litter home with them. The first one is the strict reading because it strictly preserves the part of the original sentence that is elided, and the reference is the sloppy one because it allows the reference to shift from your litter to theirs, along with the subject.

[Aside: note that the fact that the second pronoun must be them in either case, namely the sloppy reading. I'm not sure why; something about the semantics of take and home and you, probably. But it seems to be an exception to the generalisation discussed here by Neal Whitman, referring to work by Johnson and Dahl, that you can have all the possible combinations of strict and sloppy except for the one where the first is strict and the second sloppy. Which is weird.]

Unlike with most ambiguity, where context tells you which meaning is probably meant, I don't think it's so clearcut here. Presumably they are trying to shame you by saying that other people behave properly so you ought to as well (sloppy). But it is possible, I think, that it means that if you don't take your litter home, the litter-pickers will have to pick it up and take it away (presumably not literally to their homes), namely the strict reading. (We'll leave aside the point that if you take it home it's not litter, which is what my aunt Becky always points out.)

Right, I've gone on about this for so long I'm now completely unable to English so I'll do the other sign for a new post tomorrow.