Learn English – None so blind as they/them that will not see

1. You, not them, are responsible for that.

2. You, not they, are responsible for that.

Which one is correct? And why?

I'm thinking that both versions are probably acceptable.

But to show why, I'll first have to explore some related issues:

• Point One: The subject could be interpreted to be a coordination, but the verb agrees only with the first coordinate.

• Point Two: The second coordinate seems to be functioning more like supplementary information. This can be seen due to the pair of commas that delimit it as though it was a parenthetical expression, and due to the verb agreeing with only the first coordinate (it is as if the verb is treating the second coordinate as though it doesn't exist--i.e. as though the second coordinate was a parenthetical).

Notice that your example is similar in structure and meaning to:

• 3) You, and not them, are responsible for that.

• 4) You, and not they, are responsible for that.

The difference is that the coordinator "and" is explicit in these last two versions. Looking at versions #3 and #4, it seems to me that version #3 (with the accusative "them") is fully acceptable. As to version #4, it seems that it is also probably acceptable too, though perhaps it might seem to sound more formal.

Here's related info to show that the verb agrees only with the first coordinate, that the 2nd coordinate is ignored for subject/verb agreement. In the 2002 CGEL page 510:

(e) Coordination with and not or but not

Coordinations with and not and but not follow a simple rule. Since only the first co-ordinate has the property ascribed to it by the predicate, it is the first coordinate that determines the form of the verb:

[39]

• i. a. Ed, and not the twins, [ is / *are ] here.

• i. b. The twins, and not Ed, [ are / *is ] here.

(Usually, the default case for personal pronouns could be considered to be the accusative case.) In the 2002 CGEL page 461:

[14]

• i. a. Gary took the call, not I. - - - b. Gary took the call, not me.

• ii. a. A: Who ordered a taxi? B: (?) I. - - - b. A: Who ordered a taxi? B: Me.

• iii. a. A: I'm going home. B: (*) I too. - - - b. A: I'm going home. B: Me too.

Few people would use a nominative in [i], fewer still in [ii], where it would sound excessively pedantic (even more so, probably, with a negative: ?Not I ), and in [iii] it can be regarded as completely unacceptable. If the accusative is felt to be too informal for the context, the construction can easily be avoided altogether: I didn't take the call, Gary did; I did; So am I.

Notice how their example [14.i] "Gary took the call, not I/me" is somewhat similar to your two original examples, the difference being that the second coordinate has been moved to the end of the sentence.

NOTE: The 2002 CGEL is the 2002 reference grammar by Huddleston and Pullum et al., The Cambridge Grammar of the English Language (CGEL).

Despite the fact that you're referring to a singular person, yes, the custom is always to maintain the same grammatical pluralization you would if you were using "they"/"them"/"their" in the more conventional sense. The SE phrasing, "Apparently, they prefer to keep an air of mystery about them", is therefore grammatical (including the last bit, for that matter), and the alternative is wrong enough in all cases that just about any native speaker would immediately notice and be jarred by it.

The only way to use singular verbs in such a case is to switch to a different pronoun. Using "it" to refer to people is extremely dehumanizing, so that leaves only two choices:

• the awkwardly slashed "s/he" and similar (including "he or she", hat tip Steve Jessop in comments)
• new words like "zhe", "ze", "zie", "zir", "hir", and so forth, which are relatively unfamiliar and confusing to anyone outside certain circles. (Especially because of the ridiculous number of ideas people have had for such new words.)

Usually, it's not worth the hassle. Just use "they"/"them"/"their" with plural verbs. No sane person will get offended, there's no grammatical problem, and stylistically the plural pronouns are arguably the least annoying in most cases.