After the therapy, eight children (43%) became able to crawl/move on their back.

Or should I use "on their backs"?

Singular because each child only has one back, or plural because we're dealing with eight backs?

  • 4
    Related: “Only those who qualify will be awarded a certificate” or “Only those who qualify will be awarded certificates”? and the many linked questions on the right hand side of this page. – RegDwigнt Mar 6 '11 at 16:56
  • I'm more puzzled by the sample size of 18.6 children. – Phil Sweet Jul 21 at 18:58
  • A key aspect of this one is that elements of an experiment are supposed to be independent. Granularity is inherent in experimental design. Thus there were eight separate events of a child crawling on their back. Contrast this with a business closing causing 25 people to lose their jobs. I don't think it matters much whether the agreement issue crosses a prepositional phrase or clause boundary. The inclusion of the percentage value may well confuse the matter of event discreteness. – Phil Sweet Jul 21 at 20:22

Plural, because we are, in fact, dealing with eight little backs. And a back is a back, no matter how small. A child has a back, but children have backs.

I'm sure others will back me on this.

| improve this answer | |
  • 1
    Not relevant - if several children owned a single turtle between them, it would be "their turtle", not "their turtles". – lotsoffreetime Mar 6 '11 at 17:49
  • @user653: But the OP is not talking about a shared turtle. – Robusto Mar 6 '11 at 18:01
  • 4
    @Robusto, I think the point @user653 was making is that the fact that "their" is plural does not automatically imply that the word following it has to be plural too. – Hellion Mar 6 '11 at 18:24
  • @Hellion: Ah, I see. @user653 must be responding to @Fountain, not to my post itself. – Robusto Mar 6 '11 at 18:31
  • 2
    @Robusto: also, you forgot to mention that while children have backs, baby got back. :-) – Hellion Mar 6 '11 at 18:46

The semantic, grammatical, and logical arguments clearly suggest it's 'correct' to use the plural, and that's what most people do.

However, despite the fact that I doubt if any style guide endorses the singular, it seems that about 10% of usages for back persist in using the singular.

For reasons which escape me, that 'incorrect' minority rises to nearly 25% when the body part in question is chest. In both cases the evidence strongly suggests the incorrect usage is becoming more widespread.

Personally I believe it's a situation where grammarians backed the wrong horse, and their blind prescriptivism will eventually be defeated. People quite naturally want to use the singular when the number of [body parts, whatever] is immaterial, and only the plurality of [babies, people] is relevant. Increasingly, it seems, they're prepared to do this even at the risk of being considered illiterate. .

| improve this answer | |
  • Great explanation fumble. So, you are saying that it is more natural to use the singular in this case in spite of the grammatical rule, right? – Fadli Sheikh Aug 19 '19 at 23:33
  • 2
    In that graph, we have no idea of the surrounding context in which the words "on their chest" and "on their chests" are in. This question is about when the subject is plural. So it is possible that people merely discuss individuals on their chest often which tilts the data when discussing plural subjects. – Noah Jul 14 at 16:55

It is decidedly the Singular Back. This is because it is the therapy that is being evaluated but the results are singular. The children are not grouped or lined up as in a race to see who can move. The plural children is only used to describe the percentage of those who are able to move. Each child moves only on his or her own back, no other, Singular.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.