We would like to enlist your help in arbitrating this grammatical dilemma.

Given the question:

What does the door do?

Which of the following options is most correct as a response to the question?

  1. Close.
  2. Closes.

Please pick only from the given options and do not modify them in any way. (I have asked people in the past and they have responded with more-than-one-word answers. )

Please explain your answer. There are 20 dollars riding on the answer to this question.


They are both correct: they elide the beginnings of different responses.

What does the door do? [What the door does is] close.

What does the door do? [The door] closes.

If you look at the verb be, you find that the former phrasing seems to be more productive and natural, if not necessarily more correct. Using the infinitive mirrors the structure of the question.

What does the Pope do? [What the Pope does is] be Catholic.

What does the Pope do? [The Pope] is Catholic.

I asked a question about this once that may be interesting.


1. Close.

I argue that it's grammatical (I will address whether it is the best of the two shortly) through the following evolution:

"What does the door do?" ⇒ "Close [does the door]." ⇒ "[The door does] close." ⇒ "Close."

This is a bit clunky, granted, compared to "The door closes." (which would lead to "Closes."), but grammatical nonetheless.

Regardless of the above, I think the shortened response "Close." is actually the best response because of this. The original question "What does the door do?" triggers in my mind a question-response pattern used often with children or in children's books.

  • — What does a horse do? — Gallop.
  • — What does a dolphin do? — Swim.
  • — What does a door do? — Open/close/swing.
  • — What does a phone do? — Ring.
  • — What does a policeman do? — Fight crime.

The verb or verb phrase becomes infinitive-like and bypasses any subject-predicate agreement in number. Not only is this most natural of the two choices (I argue), it is through its use itself grammatical (though specialized).

Even though this is a pattern used around children, it still feels valid in my mind for adult conversation because the question itself ("What does the door do?") is very simple and carries with it, regardless of speaker, a child-like and innocent tone that invokes this specialized grammar. I believe I've even seen this pattern of speech during game shows or trivia, where simple one or two word responses are all that are allowed.

I only compare "Close." with "Closes." as those were the only two options given. Though among those choices I argue in favor of "Close.", if other choices were allowed I'd instead argue that "It closes." or "The door closes." are most natural of all. But as it stands, it is important to remind that "It closes." is not the same response as "Closes.".


I suspect this is one of those interesting cases of "competence vs performance" to put it in Chomskyan terms. If a native speaker looks at this on paper, they may well come to the conclusion that "Close" is the grammatical response (and I mean from a purely intuitive point of view, not from any 'prescriptive' point of view about what's "correct"). And I suspect that if you actually were able to take recordings of spontaneous answers to the question in real life, you may well find that what people actually say is "Closes".

For those not familiar with the phenomenon, similar things happen 'on the fringes' of grammar such as these pairs (where "on paper", our intuition tells us that only (a) is grammatical, but in practice many speakers would use (b)):

  • (a) The thing is that it's a bit expensive.

  • (b) The thing is is that it's a bit expensive.

  • (a) He's one of those people who is always there to help.

  • (b) He's one of those people who he's always there to help.

  • (a) Which of the barmen did you wonder whether would be serving tonight?

  • (b) Which of the barmen did you wonder whether he'd be serving tonight?