Should

This is my opinion:

"He should have done it": this is something you expected him to do and the fact that he did or not is not very important. And you think that it would have been much better if he had done it.

"He had to do it yesterday": this is a completed past action. You know that he was to do that, he was asked to do that and in fact he did.

So the sentences 1,3

Hello to both of you and welcome to the forums.

You can use #2 like this: He had to do it yesterday if he wanted to get the discounted price - but whether he did or not, I don't know. He had to mail the package yesterday for it to arrive on time, but he didn't get out because of the storm, so I guess it will be late.

navitasan('Should' in these sentences is supposed to express obligation.)

He should have done it yesterday means that he didn't do it yesterday. It's "counterfactual". So you can't not know. You have to know that he didn't do it to be able to say that he should have done it yesterday, in the sense that he was obliged/supposed to do it yesterday.

But Jim, aren't there situation when you don't know? You're not present, and you're just hoping he did as he was supposed to.

I wonder if we'll get the package before the first. Paul should have mailed it yesterday. Based on when it arrives, we'll know whether he or not he did.

I'm wavering on that. In that context I can see the reading "Paul was expected to have mailed it yesterday" more easily than any reading involving "obligation", which was the original poster's focus.

It's not whether that interpretation is possible, but whether it connotes obligation. "Paul was supposed to have mailed it yesterday" would be the better way to pull in the idea of obligat

Oh well - either way, it reinforces that there is a difference between asking us "is this possible?" or "is this completely wrong?" and "is this the way a native is likely to say it?"

BTW, what do you call the "should" of "She should be there by now"? The should of... expectation?

Thank you Jim and Grammar Geek.

I think here the frontiers between 'obligation' and 'likelihood' become blurred. Since he had to mail it, then it is likely that he did. But does this sound correct:

A-You should have mailed it yesterday and we still don't know if you did or not. Did you?

or this one:

Grammar Geekwhat do you call the "should" of "She should be there by now"? The should of... expectation?

Isolated like that, yes, definitely, expectation.

The bill should come to a little more than $25. (expectation)

is very different from

He should apologize for what he said. (advisability)

CJ

A-You should have mailed it yesterday and we still don't know if you did or not. Did you? Personally, I prefer:
You were supposed to mail it yesterday, and we still don't know if you did or not. Did you?

B-He should have mailed it yesterday. He had clear instructions. And we haven't received it. You were with him all d

CalifJim

Grammar Geekwhat do you call the "should" of "She should be there by now"? The should of... expectation?

Isolated like that, yes, definitely, expectation.

It's 3 am and I can't sleep. Now all I can do is picture phrases in capital letters like "The Cloak of Invisibility" and "The Sword of Invincibility" and