This is one that I’m seeing more and more.
For the longest time, I did not know there was a distinction between these two terms. In fact, I thought that can not was simply incorrect. Truth is, they are both correct in certain contexts and have distinct meanings.
- Cannot—Cannot is used for inabilities as in “I cannot go.”
- Can Not—Can not is used to describe a choice. For example, “I can not go,” does not describe the inability to go, but rather the option of not going. Instead of the “not” modifying “can” (as happens in “cannot”), “not” modifies the following word, in this case “go.”
One of the key differences is in the inflection you put on the word. In Cannot, the “not” portion of the term is not inflected. In Can Not, “not” is highly inflected. If you think of it another way, “can not” is almost asking a question or making a suggestion and is inflected that way.
What it means to me
The biggest thing is that you’ll start to notice the difference, and the difference is important. Unfortunately, you’ll start to notice that some people incorrectly make the distinction, especially in the written word. Fortunately, the difference between the two terms is so unique and specialized that you can probably figure it out just from context. That specialization is probably why so few people even know the distinction exists. I sometimes wonder if the two terms will eventually become one term with two meanings.