I have found multiple questions touching on this but not a single one that has a comprehensive answer. The information is all there but in little bits.

Exactly why is "Do not you sleep?" ungrammatical (except in poetry/with artistic license)? I understand that not can't contract after you: "Do you not sleep?" because not can only contract after a verb, and that it always does after do: "Don't you sleep?" but why does it (why must it) contract if it's placed after the verb in a question?

  • Don't you sleep? (common form)
  • Do not you sleep? (ungrammatical)
  • Do you not sleep? (less common form)
  • In "Don't you sleep?" don't being a single word, (setting aside for the present the fact that it's a contraction from two words), works as an inversion without presenting any grammatical or semantic issues. In "Do you not sleep?" not appears before sleep as an inversion. On the other hand, "Do not you sleep?" is not ungrammatical, does not fail to make sense, but finds little use because the negation appears before the noun you (the phrase you sleep), rather than the verb sleep causing semantic issues. HTH.
    – Kris
    Commented Dec 9, 2014 at 7:20
  • This may be better on English Language Learners
    – Kris
    Commented Dec 9, 2014 at 7:20
  • 4
    It's fallen out of fashion. You can find examples in Jane Austen's dialogue, where 'do not you' (rather than 'do you not') is depicted as an error which shows the speaker's vulgarity.
    – A E
    Commented Dec 9, 2014 at 7:59
  • Today, I think most people would ask "Aren't you sleeping?" or "Aren't you asleep?" rather than any variant of the question involving do or don't.
    – Erik Kowal
    Commented Dec 9, 2014 at 8:23
  • 1
    @ErikKowal I chose an intransitive verb to simplify the question in question as much as possible. And I've had people ask me "Don't you sleep" when they've expected me to not respond to them online due to the time of day ("You always respond to me quickly no matter what time of the day it is so you appear to never sleep. Is this true? Don't you sleep?"). This has a different meaning from "Aren't you asleep?" (I think most people wouldn't ask a sleeping person questions!). I could have used the examples Isn't it good?, Is not it good?, Is it not good? and the question would still stand.
    – CJ Dennis
    Commented Dec 9, 2014 at 12:28

6 Answers 6


This is an interesting question. I haven't an authoritative answer, but I can sketch the historical development and make some suggestions for how it came to be.

The first thing is that not is an anomaly in English: it is a kind of modifier that follows the word it modifies. This is normal in some languages, but unusual in English, where modifiers (such as adjectives and quantifiers) usually precede.

Historical forms like

I go not

with not post-modifying go actually arose from older I ne go nought (Old English, but with modern spelling for simplicity) where nought was optionally used for emphasis, and gradually became compulsory and ne disappeared. An exactly similar process can be seen in French Je ne sais pas. ("I don't know"), where the originally empatic pas is now normally required, and in everyday speech the ne pretty well disappears. This cross-linguistic process is known as Jespersen's cycle.

So in early modern English, the anomalous I go not was the norm.

The optional use of do with a verb goes back at least to Shakespeare's day: I do go is grammatical now as it was then (though today it has a special meaning, either I go habitually, or a contrastive or emphatic sense). This meant that in the negative I do not go was available as an alternative to I go not.

For some reason this form ousted the older form except for auxiliaries: we still say I will not, I cannot etc., but for full verbs, only He does not see it is available. My own theory is that the "do" form gained ground precisely because it restores the usual modifier-modified order: I do not go can be seen as having the pre-modifer do not before the main verb go. When the contraction don't is used, this is even stronger. But I've not seen this idea discussed anywhere.

In negative questions there is a further complication. The early modern English form was

Go they not?

which appears frequently in the King James Bible.

With the rise of do support in the negative (and interrogative), it appears too in the negative interrogative:

Do not they go?

and as A E says, this was still common in 1800, as can be seen in Jane Austen and other writers.

But there was another form which also appeared, I believe from a reanalysis of They do not go as They do (not go) rather than They (do not) go: when this was inverted as a question, the simple auxiliary do was inverted with the subject, and the not go stayed together, giving Do they not go?

When do not was contracted to the single word don't, on the other hand, this reanalysis was not possible, and the compound don't was what inverted with the subject, giving Don't they go?

As I said, this is a descriptive account, not really an explanatory one. But I suspect it is the best answer available.

  • Not is not really that much of an anomaly. It is an adverb of sorts (or at least it was, whether or not you still want to classify it as one nowadays), and adverbs frequently follow the verb they describe. Also note that “Do not they go?” is not just the do-support version of “Go they not?”. That is “Do they not go?” (subject-verb inversion + negation after subject). “Do not they go?” is the aberrant word order, and “Don’t they go?” only became so popular because it can’t be expanded once it’s been contracted. Commented Dec 9, 2014 at 18:28
  • 1
    @Colin: When Jane Austen wrote, there was a rule that you should avoid using contractions while writing. I have a theory that "Do not they go?" was originally the written-down form of "Don't they go?" (But of course, having seen it written down, some people started using it in speech.) I have no idea how to test this theory. Commented Dec 10, 2014 at 11:21
  • @JanusBahsJacquet. Hmm. Some things to think of there. You may be right about the adverbial parallel. The inversion question is more complicated, because "subject-verb inversion + negation after subject" is only the rule for pronoun subjects - for heavier subjects it is optional (eg Isaiah 28:24. "Goeth not the husbandman ever in due season earnestly to his land?"). Admittedly I was talking of pronoun subjects, but there is that model. However, there don't seem to be any examples of interrogative "Go not they", so you may be right. How then did the "Don't you" form arise?
    – Colin Fine
    Commented Dec 10, 2014 at 12:47
  • I would say (like John does in his answer) that it arose as a subject-verb, or perhaps at this stage rather subject-auxiliary, inversion of an already contracted and hence unexpandable “you don’t”. You do not => Do you not? — You don’t => Don’t you. I think of “do not you” as being essentially emphatic, with not moved up to modify you and therefore appearing out of place. To me, “Does not his very state of agitation prove that he is not the killer?” is still quite clearly emphatic, aside from sounding pompous as all hell. Commented Dec 10, 2014 at 16:18

There are several rules involved here.

  • Not-Placement, which puts not immediately after the first auxiliary verb.

  • Auxiliary-Negative Contraction, which optionally produces a single contracted auxiliary.

  • Question Formation, which inverts the subject and the first auxiliary verb.

These first three rules all require an auxiliary verb.
If there is none, one more rule gets involved:

  • Do-Support, the rule that supplies the auxiliary do to use with these rules.
    (Auxiliary do carries the tense, so the main verb is changed to an infinitive)

In modern English Do-Support is obligatory; i.e, we can't ask questions like

  • *Slept you 8 hours yesterday?

any more.

Furthermore, Auxiliary-Negative Contraction produces a single contracted auxiliary.
And it does so optionally; this means one can form a question either with or without contraction.

So let's form questions both ways and see what happens.
You slept 8 hours yesterday. (Base sentence)

Here's negative question without contraction:
You did not sleep 8 hours yesterday. (Not goes after Do-Support did)
Did you not sleep 8 hours yesterday? (Auxiliary did inverts with subject you; not stays put)

Here's negative question with contraction:
You did not sleep 8 hours yesterday. (Not goes after Do-Support did)
You didn't sleep 8 hours yesterday. (Contracted auxiliary formed)
Didn't you sleep 8 hours yesterday? (Contracted auxiliary inverts with subject you)

As you can see, the question rule is quite specific. The first single auxiliary verb can invert, and contracted auxiliaries are single auxiliary verbs. And there's no other rule to move the uncontracted negative along with the auxiliary. After all, until it's contracted, not is just another adverb.

In general, once a word has been reified, it's a different word, with different affordances.

  • 1
    OMG, it's a good thing I'll be travelling this week. This is my 999th answer, and I'll hafta plan a party for when I score a kilo. Commented Dec 9, 2014 at 19:21
  • So you agree with others that the now anomalous Did not you sleep was derived from Didn't you sleep rather than existing on its own? Or are you not talking diachronically at all?
    – Colin Fine
    Commented Dec 10, 2014 at 16:42
  • 1
    I have no opinions on the historical sources of syntactic constructions. Mostly they don't have only one; syntax is not genetics, pace Chomsky. Commented Dec 16, 2014 at 15:44
  • 1
    Forget opinions, have you heard any speculations where the construction of do-support came from? Welsh? Pictish? Thin air?
    – Mitch
    Commented May 19, 2015 at 17:33
  • Probly Martians in the woodpile. Commented Jun 19, 2015 at 14:55
  • Don't you sleep?
  • Do you not sleep?
  • *Do not you sleep? (weird)

Whilst it's a good question, the assumption in the Original Poster's discussion is kind of the wrong way round. It is not the case that "not" must contract when it appears directly after the auxiliary verb. What's happening is that, to make the sentence into a question, the auxiliary is moved to the front of the sentence from its normal position:

  • You do sleep.
  • Do you sleep.

Not can only move from its normal position if it's stuck to this auxiliary verb. It's the auxiliary that's carrying not round to the front of the sentence. It can only do this if they're joined together.

If not isn't contracted, it must stay in the same position it has in a normal declarative sentence. Below the parts that invert are in light font, the rest of the sentence is in bold. In sentence (3) we see not moved away from it's normal position because it's attached to the auxiliary verb. It's sandwiched between the auxiliary and the subject:

  1. Tom does not like Sally (normal negative sentence)
  2. Does Tom not like Sally (no contraction, not in normal declarative sentence position)
  3. Doesn't Tom like Sally (contracted with auxiliary, n't appears in pre-subject position)
  • Your positive statement seems to highlight my question if I make it negative and then turn it into a question: You don't sleep: Don't you sleep?, You do not sleep: Do not you sleep?: Do you not sleep? Are you saying that in your next example it should be highlighted as Tom does n't like Sally?
    – CJ Dennis
    Commented Dec 10, 2014 at 2:22
  • @CJDennis Have now explained above! Commented Dec 10, 2014 at 9:18

For instance : *do not you speak English? is ungrammatical because under negation "not" is a SPECIFIER and the contracted form "-n't" is a HEAD, and DO stays at TENSE and it is a HEAD.

Based on the "head movement constraint" heads moves to heads and specifiers to specifiers only.

When making a questions, head do carrying tense moves to complementizer phrase (CP), specifically under "force head", and when adverb specifier "NOT" tries to move together, it is blocked based on the above principle (SPEC can not move to HEADS).

Conversely, negation head "-n't" can adjoin do head before moving to CP, as an affix (not a clitic), forming a new word "don't" (head -n't adjoined with head DO), and then the newly formed head don't can move to CP head = Don't you speak English? which is perfectly grammatical.

  • 1
    You should include references or explanations for the terms you're using (such as "head movement constraint"). Commented Jul 17, 2022 at 14:20
  • 1
    As it’s currently written, your answer is unclear. Please edit to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers in the help center.
    – Community Bot
    Commented Jul 17, 2022 at 16:41

You made the presumption that "don't" is the root, and that "do X not" is the derivative.

Have you ever considered asking the more proper question? Which is

  • Why is it valid to contract "Do you not sleep?" to "Don't you sleep?"

You are performing a reverse-derivation and then presuming the reversed derivation as the root.

Just as the decision to "dial" a cell phone made by this generation, these are the decisions made by the ancestors of the English language we speak

  • Why can they not X?
    contracted to
    Why can't they X?

  • Do they not X?
    contracted to
    Don't they X?

  • Do not they X?
    was not even in the picture.

  • No, I was asking why in negative questions Don't ...?, Isn't ...?, etc. don't expand to Do not ...?, Is not ...?, etc. in modern English.
    – CJ Dennis
    Commented Dec 9, 2014 at 12:39
  • @CJ That’s actually just what was said here. Historically, the canonical word order in questions was Verb Adv/Part Subj (“Do I not…?”, “Do I ever…?”, etc.). Where things go wrong is that not can contract with verbs, and when this happens and inversion is required, the contracted form cannot be expanded. So “Don’t I…” is not expanded to “Do I not”—it doesn’t expand at all. It can’t expand. Formerly (and poetically), Verb Adv/Part Subj was also possible, so “Do ever I…?” and “Do not I…?” do appear; but not in idiomatic, current English. Commented Dec 9, 2014 at 18:19
  • @JanusBahsJacquet I was trying to say that I wasn't making presumptions, I was just asking a question because I was curious about this aspect of English and wanted an answer more than "that's just the way we do it because of English language history". I think what you wrote is deserving of an answer, possibly even the accepted answer.
    – CJ Dennis
    Commented Dec 10, 2014 at 2:12
  • @CJDennis -- if you were wondering why "Don't I" is not expanded to *Do not I, it's because "expansion" doesn't exist. You can't just expand any word anywhere. There has to be a rule, and there isn't one. There is a rule of contraction, but it doesn't work in reverse to form new sentences. Commented Jul 17, 2022 at 15:21
  • Do I not know? Would I not know? Commented Aug 11, 2022 at 2:42

The simple reason is that the word "do/does" comes from a foreign grammatical rule that the Scandinavian Vikings brought when they invaded England. Structures like "I do not like that" and "What does he do?" came from Old Norse. They also brought new grammar like "they,them, their", that eventually replaced our native Old English.

  • 2
    Could you provide a citation for this? It seems a bit confused, and not consistent with what I've heard about the matter. The pronouns "they, them, their" do indeed seem to be from Norse, although I'd call them vocabulary rather than grammar. But I haven't heard of any Norse influence on English negation or question formation.
    – herisson
    Commented Dec 14, 2016 at 20:45

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

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