I am always correcting people when I see “can not” written on a page, yet having recently researched this topic, I have ended up with egg on my face, as it were.
Merriam-Webster states “cannot” is one word, and if you Google “can not,” you will be sent to a list of suggestions headed by “cannot.”
But hang on there a minute…
According to the entry in the Oxford English Dictionary, “cannot” is
the modern way of writing “can not.”
Historically, OED illustrations show examples for 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?”
While we certainly shouldn’t use “canot” in the modern day (my Word grammar check has just gone off), there is no difference in meaning between these two versions, and what’s more, “can not” is a perfectly acceptable way of spelling “cannot.”
As a last authority on the subject matter I checked out the Washington State University language website, and here’s what it had to say:
“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.”
I certainly won’t be telling anyone “can not” isn’t correct anymore!
