will/would have returned home

[lagoo]

The use of "would have" is always very tricky to me, so I made up all these sentences, which might be wrong, together with my analyses. I hope this time I will get a thorough understanding of "would have" with your precious and insightful help.

1) I think Tom will have returned home now.
The speaker is quite certain that Tom has returned home.

2）I think Tom would have returned home by 6 p.m.(Now, it's 9 p.m)
The speaker is quite certain that Tom had returned before 6 p.m.

3) I thought Tom would have returned home by now.
"Tom would have returned home by now" was my thought at a previous time than 'now'. This is just a time shift version of "Tom will have returned home by a future point of time".

4) It was 6 p.m. and I thought Tom would have returned home.
The speaker was quite certain that Tom had returned home before 6 p.m.

5) It was 6 p.m. and I thought Tom would have returned home if not for that delayed bus.
Tom had not returned home.

6) I think Tom would have returned home tomorrow if not for that delayed bus.
Tom is unlikely to return home tomorrow.

 

[lagoo]

Your understanding would have been correct if the speaker had not begun with "I think".

(Sentence 1) Does that also mean I can't use 'I believe', 'I assume' or 'I'm sure' either, because 'will' itself expresses certainty?

If you drop the "I think", then the speaker is asserting a hypothetical certainty about Tom's return.

(Sentence 2) So without 'I think', 'the hypothetical certainty' means the reality is that Tom had/has not returned, by 6 p.m. or by now?

 

[emsr2d2]

I don't think it's unreasonable to assert certainty with "I'm sure".

 

[jutfrank]

I think it helps to understand the notion of certainty as a scale of degrees rather than as a mental state of doubtlessness, where the following sentences all employ the modal will to express the notion of certainty, and other words to indicate the degree.

I don't think it'll work.
I think it'll probably work.
I'm absolutely sure it'll work.

 

[lagoo]

Would anybody like to proceed with my questions from (3) to (6)?

 

[jutfrank]

Would anybody like to proceed with my questions from (3) to (6)?

Not really. I'm not sure they are natural enough for you to worry too much about, or for us to invest time into. Maybe if you post them one at a time, it might encourage people to answer. I think that to understand this properly, you really need to make sure the sentences are likely things that native-speakers would utter.

To add to your confusion, a lot of people might say this:

I would have thought Tom would be home by now.

 

[Tarheel]

Bob: Tom should have been here by now.
Dave: He called and said the bus broke down and he had to take a later one.
Bob: OK.