I should know that by now, shouldn't I?

[EngLearner]

Source: "The Stake Killer", a movie (timestamp: 1h26m54s).

A guy and a girl live in different time zones. The guy calls the girl, and the following conversation takes place between them:

Girl: "No, I wasn't about to go to bed."
Guy: "Well, I don't just want to keep you awake."
Girl: "No, that's OK."
Guy: "What time is it over there?"
Girl: "It should be like eleven or something."
Guy: "I should know that by now, shouldn't I?"

I remember talking to an American English speaker, and the situation was similar: she wanted me to confirm something she didn't know, then I did, and then she said: "I should've known by now." Are both "should know" and "should have known" correct in the dialog from the movie? If so, does either of them mean something different than the other does in such a context?

 

[jutfrank]

No, I should have know that by now is not correct in this context, since know is stative.

 

[EngLearner]

If I take out "by now" from the dialog:

I should've known/should know that, shouldn't I?

Which form would be used? I think the perfect form is correct implying that before I just asked you I didn't know that, but I should have.

 

[jutfrank]

If I take out "by now" from the dialog:

I should've known that, shouldn't I?

No, that's wrong. The phrase I should've known has a very different meaning/use. It doesn't work here.

If I take out "by now" from the dialog:

I should know that, shouldn't I?

Yes, that's good. It has the same meaning/use whether you use by now or not.

 

[jutfrank]

I think the perfect form is correct implying that before I just asked you I didn't know that, but I should have.

Think about the meaning of the verbs. The verb 'know', being stative, cannot express an action that can be accomplished, so you can't use a perfect aspect with it. Knowing is not something you can do.

For the sake of explanation, let's change the verb to 'learn'.

I should've learned that by now.

Now, it's good, because learning is something that you can do. Equally, you can't now say:

*I should learn that by now.

 

[EngLearner]

Think about the meaning of the verbs. The verb 'know', being stative, cannot express an action that can be accomplished, so you can't use a perfect aspect with it.

But if someone is talking about a state (not an action) in the past, then, as far as I know, the perfect form can be used with stative verbs:

I should've known that then, but I didn't.
I should've been there then, but I wasn't.

The same way as the simple form is used with stative verbs when talking about a state in the present:

I should know that now, but I don't.
I should be there now, but I'm here instead.

 

[jutfrank]

Yes, that's all correct. I didn't mean to suggest you can't ever use stative verbs with a perfect aspect, if that's what you mean.

I think what may be troubling you is that you think the utterance is talking about the past. It isn't. The speaker is saying something equivalent to 'It should be the case now that I am in a state of knowing what time it is in the girl's time zone'. He's talking about his present state of knowledge/ignorance.

 

[EngLearner]

I think what may be troubling you is that you think the utterance is talking about the past. It isn't. The speaker is saying something equivalent to 'It should be the case now that I am in a state of knowing what time it is in the girl's time zone'. He's talking about his present state of knowledge/ignorance.

Yes, you're right. That's exactly what was troubling me. I was going to post this before you edited your post:

The guy now knows that it's around 11:00pm in the girl's country, but a second ago he didn't know that. That's a state in the past, so logically it should be:

I should've known that a second ago, but I didn't.

But if he says "I should know that, shouldn't I?", then it's like this saying:

I should know that a second ago, but I didn't.

Unless the meaning is "I should know that from now on, shouldn't I?", then there's a logical discrepancy there: "I should know" doesn't match "I didn't know."

 

[jutfrank]

The guy now knows that it's around 11:00pm in the girl's country, but a second ago he didn't know that. That's a state in the past, so logically it should be:

I should've known that a second ago, but I didn't.

But he isn't talking about what he didn't know a second ago. He's talking about now, and the fact that he still hasn't yet memorised the time difference and so still has to ask her what time it is. In that sense, even though she has just told him it's 11 o'clock, he still hasn't properly succeeded in committing to memory the precise difference in time zones. We can gather from this exchange that he's failed to learn the time difference on one or more previous occasions and quite possibly will fail to do so again.

But if he says "I should know that, shouldn't I?", then it's like this saying:

I should know that a second ago, but I didn't.

Unless the meaning is "I should know that from now on, shouldn't I?", then there's a logical discrepancy there: "I should know" doesn't match "I didn't know."

Again, he's not talking about the past, but rather about the present. He's likely saying 'Considering all the previous times I've had to ask you what time it is, I should be expected to have learnt such information, which is evidently not the case.'

 

[EngLearner]

Source: "Mafia: The City Of Lost Heaven", a computer game (timestamp: 17m37s).

Tom needs to steel some crates from a warehouse, so he's pretending to be one of the workers of that warehouse. His problem is that he's not alone in there: the chief is also in the warehouse. In order to make him go somewhere far from there, Tom says to him: "Chief, the boys at the train there need you. They're having some problems." The chief replies to Tom:

I should've known. As soon as I turn my back, everybody immediately goofs off.

If the chief had put "by now" at the end of the sentence:

I should know by now. As soon as I turn my back, everybody immediately goofs off.

then he would've had to use "should know" rather than "should've known", right?

 

[jutfrank]

This is a decent example of the use of the fixed expression I should've known!, which I alluded to in post #4. It's a phrase that expresses frustration at having missed or failed to pick up on something. It's loosely equivalent here to something like 'How typical of them to do that, and how silly of me to have trusted them in the first place.'

It doesn't work or indeed make any sense with 'by now' after it. It's a fixed phrase, so you can't change it. Don't try.

 

[EngLearner]

Girl: "No, I wasn't about to go to bed."
Guy: "Well, I don't just want to keep you awake."
Girl: "No, that's OK."
Guy: "What time is it over there?"
Girl: "It should be like eleven or something."
Guy: "I should know that by now, shouldn't I?"

Would it be correct to put it like this as well:

1. I should know by now.
2. I should know.

 

[jutfrank]

Stop trying to 'correct' things. The original is perfect as it is.

Look—let me put these two very different expressions you've asked about very clearly:

1) I should've known!

This is a fixed expression that can't be changed. It's an exclamation of frustration/regret, as I've outlined above.

2) subject + should know (something) by now.

This is a semi-fixed expression, used to say that you haven't yet fully learned something before the present moment.

Study and learn these expressions. Don't try to deviate from them.