[tshaddox]

I’m not confused about what any of these words mean.

> You shouldn't climb over an electrified fence. You might have to — it might be best to do so — if you're being chased by a bear.

And in that case you should climb over the electric fence. It’s nonsense to say that you “must” or “have to” climb over the electric fence but that you “should not.” The first sentence is, as is abundantly clear to all English speakers, a shorthand for “you shouldn’t climb over an electric fence except for very rare cases where it will be obvious to you that you’re encountering an exception.”