I have to admit I decided to write this post because I really wanted to know the difference between “can not” and “cannot” for myself.  I was proof reading some of my own writing recently and I realized I was not 100% sure on the difference usage of “can not” and “cannot”.  Even as a native speaker or English, an ESL teacher, and a person who has studied Linguistics at the graduate level, I did not know the difference between these two words off the top of my head*.  I figured many of you out there may not know the difference either, so I did some investigating for all of us.  What I found was a little contradictory and I realized that the reason that I don’t know the difference between “can not” and “cannot” is that 99% of the time the difference doesn’t matter. Either that or I was sick the day my teacher taught this lesson in my elementary school English class 🙂

If you look up the word “cannot” in a dictionary you will find the definition is “the negative form of can” and it may also note that “cannot” is the contract form of “can not.”  (Note: “can’t” is also a contracted form of “can not”.)  Based on this information it appears there is no difference between the words “can not” and “cannot.”  In my investigations on this subject I also read these two spellings (“cannot” and “can not”) are for the most part interchangeable**, but the more common spelling is “cannot” and that this should be used except when someone wants to be emphatic***, then use “can not.”  But that is not the whole of the story!

Although it appears in general most people do not see a notable difference between “can not” and “cannot”; there is in fact a difference. Here is an explanation of the the difference between these two word: If you “can not” do something, then you “can” also do it, but if you “cannot” do something then it means the thing is impossible to do.

For example: I can walk or I can not walk to school, but I cannot fly to school (unless I take an airplane).

Here is another way to look at this difference:

can + (something) = the ability to do (something)

can not + something = the ability to not do (something
(This means you have the option to do something or not.)

cannot + something = the inability to do (something)
(This means no matter how hard you try to do something it is actually impossible.)

Okay, I think I understand the difference now and I hope you do too!  There is a very small difference in “can not” and “cannot.”  I will try to use these two words correctly from now on and hopefully you will too.  I can not believe I didn’t know this before!

*off the top of my head = this is an expression that means: with quick recollection or knowing something without having to think about it
** interchangeable = two things are capable of being put or used in the place or each other

*** emphatic = showing or giving emphasis; expressing something forcibly and clearly