“can’t lives on won’t street – i’m sure my son will hate me when he’s older for saying that all the time.”
I like it. It reminds me of an article that I drafted a few months ago but hadn’t posted yet. Here it is…
When I ask for help sometimes, I find myself writing a sentence that ends with, “…but I can’t figure it out.” I try to catch myself when I do that, because can’t is not the correct word.
Here’s what can’t means. Imagine a line representing time, with the middle marking where you are at some “right now” instant in time. The leftward direction represents the past, and the rightward direction represents the future.
Can’t means that I am incapable of doing something at every point along this timeline: past, present, and future.
Now, of course, can’t is different from mustn’t—“must not”—which means that you’re not supposed to try to do something, presumably because it’s bad for you. So I’m not talking about the can/may distinction that grammarians bring to your attention when you say, “Can I have a candy bar?” and then they say, “I don’t know, can you?” And then you have to say, “Ok, may I have a candy bar” to actually have candy bar. I digress.
Back to the timeline. There are other words you can use to describe specific parts of that timeline, and here is where it becomes more apparent that can’t is often just not the right word.