cannot (one word) is the expanded form of the contraction can’t.
Can’t can also be expanded to can not (two words), but this usage is relatively rare and is sometimes just for emphasis.
For example:
I cannot do it!
Can’t is usually expanded to cannot.
I can not do it!
This is more emphatic.
Of course, can and not sometimes just happen to be next to each other due to their respective collocations.
For example:
Kevin can not only rap but dance too.
Kevin can both rap and dance.
Here, can not must be written as two words, and is not the expanded form of can’t.
◆◆Cannot or Can Not?◆◆
cannot and can not can be used interchangeably when they are the expanded forms of can’t.
However, in modern usage, people tend to prefer cannot. It is worth noting that many spell check software even highlight can not as a spelling error.
◆◆ Examples of Cannot and Can Not◆◆
Here are some quotes containing cannot and can not for reference:
You cannot escape the responsibility of tomorrow by evading it today.
Today you evade responsibility, and it still exists tomorrow.
-Abraham Lincoln
There cannot be a crisis next week. My schedule is already full.
There cannot be a crisis next week; my schedule is already full.
-Henry A. Kissinger
Conflict can not survive without your participation.
Conflict cannot arise without your participation.
-Wayne Dyer
A flower cannot blossom without sunshine, and man cannot live without love.
A flower cannot bloom without sunshine, and a man cannot live without love.
-Max Muller
Three things cannot be long hidden: the sun, the moon, and the truth.
There are three things that cannot be long hidden: the sun, the moon, and the truth.
◆◆Using Can Not for Emphasis◆◆
Only when not is used for emphasis should you consider using can not instead of cannot.
For example:
I can not tolerate laziness!
I cannot tolerate laziness.
Using the two-word form makes the emphasis of not clearer. This is usually used in exclamatory sentences, which are sentences that end with an exclamation mark.
◆◆
When Must You Use Can Not
◆◆
When using can and not as two separate words, the form can not can appear, especially in the conjunction not only…but also.
Danielle can not only cook but also bake.✔
Danielle can not only cook but also bake.
My dog can not only roll over but also play dead.✔
My dog can not only roll over but also play dead.
In such sentences, cannot cannot be used.
