Cannot or Can Not?

What is the difference between ‘can not’ and ‘cannot’?

Although my personal Error Alarm buzzes whenever I see cannot written as two words, both forms are acceptable usage.

Merriam-Webster lists cannot as one word. If you try looking up “can not” in the online unabridged, you will be sent to a list of suggestions headed by cannot.

According to the entry in the OED, cannot is

the ordinary modern way of writing can not

The historical illustrations given for the negative in the OED shows cannot, can not, and even canot, as well as the contraction can’t:

a1400 Cursor M. (add. to Cott.) p. 959. 105 And ?ou ?at he deed fore cannot sorus be. 1451 Paston Lett. 140 I. 186 Other tydyngs as yett can I non tell you. Ibid. 172 I. 229 Whethir it be thus or non I can not say. 15.. Plumpton Corr. 72, I canot get my money. 1706 Col. Records Penn. II. 256 The House cant agree to this. 1741 RICHARDSON Pamela I. 56 If he..as you say can’t help it. 1742 YOUNG Nt. Th. I. 89 An angel’s arm can’t snatch me from the grave; Legions of angels can’t confine me there. 1827 KEBLE Chr. Y. 4 Without Thee I cannot live. Mod. Can’t you go?

The experts at AskOxford seem to prefer cannot:

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.’

The Washington State University language site says:

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.”

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

 

Other idea:
“Cannot” is unequivocal: it means you do not have a choice; something you cannot do is not something you “can” or “can not” do. It means that you are not able to do that thing.

You “can” or “can not” take the dog for a walk, depending on your mood. If you are confined to bed with a broken leg, however, you “cannot” take the dog for a walk, regardless of your mood.

总结：大多数情况下用cannot, 用can not 时是强调not，或者not 属于另一个词组，如not only... but also...中的not.

亦有人认为，cannot= not be able to 不能

                        can not= not to do 可以不