Not your run of the ‘will’ tag question

The following example is from an Italian Quiz book whose aim is to help candidates prepare for English multiple choice tests. In many government run “concorsi” (competitive exams) you might have to answer up to 100 questions in an hour or less. The fact is, you can't afford to spend time figuring out the answer, it's–as I see it–a way of testing someone's fluency without actually doing a speaking test.

So, I'm going through these examples with a private student, who tells me she got question 146 wrong (the answers are at the back of the book)

146 Don't eat all the cherries,…?

A) do you
B) will you
C) shall you
D) don't you

I make the classic mistake of not reading the question properly, and go on auto-pilot mode, the answer, I tell her, is A) because if the verb in the main clause is negative, the auxiliary in the question tag should be positive, e.g.

• She doesn't like modern jazz, does she? (NB –doesn't she? would be considered a mistake in most English tests)
• They don't believe in elves, do they?

Similarly, when the verb in the main clause is positive, the auxiliary used in a question tag, is often negative. For example,

• He writes poetry, doesn't he? (or –does he?)
• They live in Guatemala, don't they? (or -do they?)

The student then tells me that A) was also the answer she gave but it conflicted with the key. Oops!

I read the complete sentence aloud and my rushed solution sounds all sorts of weird.

• Don't eat all the cherries, do you?

Technically, it appears to be grammatical a bit like Chomsky's colourless green ideas sleep furiously, albeit a lot less fantastical. The meaning of the sentence is confusing, as it appears the question tag follows the simplified "rule" mentioned above but its meaning is contradictory.

The correct answer, after a few moments of hesitation, is B) I tell my student, which the book confirms.

• Don't eat all the cherries, will you?

I explain why C) and D) do not work but I falter on A), until I surmise that the question tag -will you? is not really asking the listener to confirm a statement but to comply with the command ‘Don't eat all the cherries,…’ the ‘will you’ is the short version of “Will you do as told/instructed?” It has little or nothing to do with its future meaning, and it sounds passive-aggressive to my ears.

I think I'm right, aren't I?

A tag after a declarative is checking whether the sentence is true, and that's why you see the same auxiliary used in the sentence. We stress auxiliaries or move them to the front of the sentence when we want to emphatically show a sentence is true or ask whether it is true, respectively. However, a tag after an exclamative is not checking whether something is true. It is checking whether you are going to comply with the imperative, which is why it uses the modal will. The will here is not only about predicting the future it is also about your volition/behaviour/decisions. That's why it can't easily be replaced with a different auxiliary.