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Why is “cannot” spelled as one word whereas other similar constructions such as “do not,” “will not,” “shall not,” “may not” and “must not” are spelled as two words (unless they are contracted as “don’t” and so on)?

(I know that languages are not always logical, so I would not be too surprised if there is no known reason for this. But I am asking this in the hope that there is some explanation.)

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I don't have the reputation to give this a full answer but I suspect it's to do with the scope. "will not go" is "will" + "not go" = "will stay" whereas "cannot go" is negating the "can". i.e. it means "unable + go" not "can stay". In short, the not in "can" negates the "can" whereas the "not" in "will" negates the following verb. – Gazzer Nov 10 '13 at 6:49

Etymonline says:

c.1400, from can (v.) + not. O.E. expressed the notion by ne cunnan.

This doesn't really help, but it is a good starting point. The OED supplies the 1400 cite as follows:

Cursor M. (add. to Cott.) p. 959. 105 And þou þat he deed fore cannot sorus be.

It also defines cannot as:

the ordinary modern way of writing can not

Both Merriam-Webster and Wiktionary agree, by defining cannot as can not.

The Daily Writing Tips expand on this, their bottom line being:

There’s no difference in meaning between cannot and can not.

Funnily enough, they come to that conclusion after quoting two resources that say something slightly different:

  1. The Washington State University language site:

    These two spellings [cannot/can not] are largely interchangeable, but by far the most common is “cannot” and you should probably use it except when you want to be emphatic: “No, you can not wash the dog in the Maytag.”

  2. AskOxford:

    Both cannot and can not are acceptable spellings, but the first is much more usual. You would use can not when the ‘not’ forms part of another construction such as ‘not only.’

That last point is especially interesting. A very similar concern is being raised on the Wiktionary Talk page for cannot:

Maybe our current definition is wrong or incomplete. To me, "cannot" and "can not" are different words. "I can not sit down" means you have the option of not sitting down, but "I cannot sit down" means you don't have the option of sitting down. "can not" is rarely used baldly like that, it's usually used with "only" - "I can not only get to the school, I can get there in 10 minutes!".

To the extent that "can not" is an acceptable way, at all, of writing "cannot" (also written "can't") - I bet it is only because it is such a common mistake.

That post goes on to link to this blog:

My public school teachers said can not was the correct form, and that cannot was a corruption. A friend of mine from a previous generation was taught the opposite.
Here's the explanation: If I can not do something, then I can also do it. I can not write these words if I choose (and you may think I shouldn't), but I also can, and am, writing them. What I cannot do is know who will read them, or what they will think. I can imagine such things, but I'm limited by my experience and perceptions. So this is the rule: if you either could or could not do something, then you use two words, because you can leave out the second word if you so choose. If you could not do something no matter how much you desired or tried, then you use one word, cannot. There is no other option.

Sometimes both are true. Witness:

  • I cannot change the world.
  • I can not change the world.

Languagehat chimes in:

[The Merriam-Webster definition of cannot as can not] is appalling for two quite distinct reasons: from a copy-editing point of view because it implies that cannot and can not are interchangeable, and from a lexicographical point of view because it's a lousy definition. The definition of cannot should be either "the negative form of can" (as the AHD has it) or a periphrasis like "is not able to." The only context in which can not, two words, occurs is as an emphatic alternative: "You can do it, or you can not do it." In that case, it is clearly two separately spoken words, with the not given special emphasis, and equally clearly it means something very different from cannot, namely "have the option of not (doing something)." The only acceptable form for the unabbreviated negative of can (or, if you prefer, for the expansion of can't) is cannot, one word.

Take from all that what you will. Some of it is probably justification in hindsight, and certainly none of it actually explains how that 1400 cite came about and why this particular spelling prevailed over can not, canot, cant, and can non. As you say yourself, languages are not always logical.

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This is a wonderful answer on the relationship between "cannot" and "can not", but the question of why and how "cannot" became a single word is left open. :-) – ShreevatsaR Oct 29 '10 at 14:20
@ShreevatsaR: exactly. I thought I was openly admitting that in the last paragraph, but I'll gladly use this comment to admit it again. I didn't know the answer, so I looked in a number of places, but I still don't know the answer, and I don't want to speculate. Without hard data, any guess is as good as any other. – RegDwigнt Oct 29 '10 at 14:26
Thank you for a research about the general problem of “can not” vs “cannot.” (+1 for this.) I take this answer as “there is no widely accepted explanation.” – Tsuyoshi Ito Oct 29 '10 at 16:31
I kinda wish there were something said here about how these function under question-inversion. You cannot answer > Can you not answer versus You can’t answer > Can’t you go. So the contractions have actually become fused lexemes, while the cannot version still allows for normally auxiliary inversion, splitting off the negating part. But perhaps that has been addressed in some other answer somewhere. – tchrist Oct 23 '14 at 3:56
you did not answer the question, you rather re-enforced it. – user109405 Feb 12 '15 at 10:55

The double "n" is the best and likeliest explanation for why this convention long ago became established. Problems of clarity or pronunciation would seem to arise with the other modal forms you list (since they don't end in n) should you drop the space.

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"do not", "don't" and "donot" (reminding my of the fact that I am hungry) make a good case for that. On the other hand, nobody cares about change in pronunciation when forming "don't" or "won't". – malach Oct 29 '10 at 8:20
This reason seems plausible. Also I found that OED lists “wonnot,” “winnot,” “willot” and so on as negative forms of “will” but no similar words for the negation of “may,” which might serve as an evidence supporting that the repetition of the same consonants has something to do with the spelling of “cannot” as one word. @Ralph: You reminded me that I am hungry! :( – Tsuyoshi Ito Oct 29 '10 at 16:34

One of the reasons is that "can not" is ambiguous while others are not, e.g. "will not", "do not", etc.

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"may not" is ambiguous. – deft_code Jan 3 '12 at 19:16

This is that rare case when I disagree with Microsoft in its decision (Microsoft has decided to stick with "cannot" (dropping "can not") in its docs).

As I understood, the answer(s) to this question told about possibility of 2-word "can not" only.

I'd like to add on cases of impossibility of using one-word "cannot".

For example, this post tells that "cannot" can't be used in:

  • Cannot it be without repetitions? - incorrect
  • Can it not be without repetitions? - correct

And another post in the same thread tells:

  1. I can't open the door.

    meaning, because it is stuck

  2. I cannot open the door.

    meaning, because it is forbidden.

  3. I can not open the door or I can open it.

    meaning, I have a choice.

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(1) From the blog: “One of the testers actually dug up a series of bugs where we changed one message back and forth several times. Well, I am happy to say that we have the official word on this.” Interesting. (2) I do not agree that “I can’t open the door” and “I cannot open the door” have different meanings. – Tsuyoshi Ito Mar 8 '11 at 18:24
@Tsuyoshi Ito: as a native English speaker I agree with you on (2). @vgv8 is right to point out the distinction between (2) and (3), though. – user1579 Mar 8 '11 at 18:51
@Rhodri: I agree with you and vgv8 on the difference of the example 3 … as a non-native speaker of English. :) – Tsuyoshi Ito Mar 8 '11 at 19:00
@Tsuyoshi Ito, I disagree to disagree :-) – Gennady Vanin Геннадий Ванин Mar 8 '11 at 19:04

protected by tchrist Jun 9 '14 at 19:27

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