A.1. The guests will have arrived last night. I could hear voices in the next room before I went to bed.

A.2. The guests would have arrived last night. I could hear voices in the next room before I went to bed.
B.1. The lights are on. John will still be reading his paper.

B.2. The lights are on. John would still be reading his paper.

Can both A.1. and A.2. be glossed as: It is almost certain that the guests turned up last night?

Can both B.1. and B.2. be glossed as: It is almost certain that John is still reading his paper?

Any nuances between A.1. and A.2., B.1. and B.2. respectively?

  • The only one of these construction that I've heard and would use is B1. Note that I am a speaker of American English and some of these (particularly A1) sound like they might be common in British English. I really wouldn't even say B1 ever. Instead I would say "The lights are on. John must still be reading his paper." Or "The lights are on. John is still reading his paper." Would and will feel more like they belong in conditional statements, and there are no conditions in these sentences. Sep 15, 2015 at 13:19
  • @ToddWilcox I totally agree, but the question I quoted in the tetsujin's comments says "would have done" can be used to make an inference. For example, A: A message was left on your desk. B: That would have been John. How do you account for this?
    – Kinzle B
    Sep 15, 2015 at 14:48
  • A2 doesn't seem like an inference, instead it seems like a conclusion. "I could hear voices in the next room before I went to bed last night, therefore I conclude that the guests arrived." Contrast with, "I have no information about what happened, but normally the guests would have arrived last night." Similar with B2 - the lights being on is too much information. Strangely, just knowing the time alone makes more sense for "will" or "would". As in: "It's six o'clock, John will/would still be reading his paper." We don't have any evidence about what John is doing except what he normally does. Sep 15, 2015 at 14:59
  • I see now I'm agreeing with Testujin: There is too much evidence/information for "will" or "would" to normally be used in these cases. Knowing or concluding based on other facts is different from inferring or supposing. Sep 15, 2015 at 15:03

1 Answer 1


A1 'will have arrived' would suggest you have strong certainty that they should have arrived, but no absolute proof they did. Your second sentence appears to be that proof.
That would make A1 into

"The guests arrived last night. I could hear [their] voices in the next room before I went to bed."

…unless you had burglars ;-)

A2 'would have' suggests they ought to have arrived, but didn't. So doesn't fit with the additional evidence of the second sentence.

B1 That makes sense & is a safe assumption to make, assuming you know John is likely to be there & is in the habit of reading his paper.

B2 Again, the use of 'would' suggests that normally he reads the paper, but this time something prevented him, or he finished reading earlier.

  • Can't "would have done" be used to make assumption or speculation? english.stackexchange.com/questions/134926/would-have-done This post says it could, but I doubt that. What do you think of it?
    – Kinzle B
    Dec 4, 2014 at 1:57
  • 1
    That post explains it better than I can, really. Based on that, A2 would work - but it still doesn't quite feel comfortable, it feels like it's looking for an if-clause, even though it doesn't have one. To push it clearly one way or the other, an if-clause, or more of an assumption; maybe '..would have arrived last night. Their car wasn't there when I went to bed but was in the driveway this morning.' In the link the examples are all really clear-cut. I don't seem to be able to set your example as cleanly. (My fault, not yours, btw;) Dec 4, 2014 at 7:25
  • Is this particular usage of "would" (assumption, not hypothetical) commonplace? I ask this because I almost never come across it in any books or movies except for these examples. The hypothetical use always prevails.
    – Kinzle B
    Dec 4, 2014 at 9:10
  • I'd say quite common, yes. <- in fact I did it right there without even thinking about it, though not in the same tense. I am feeling a bit 'Heisenberg' on this particular question, though - the more closely I examine it, the more uncertain the details seem to become. To push B2 [an easier one to work on] into that form, I'd use perhaps "The lights were on. John would have been reading his paper [by that time, based on his usual habit]" I'm finding it difficult to tie down any further, I could really do with a helping hand from a proper native grammarian;) Dec 4, 2014 at 9:26
  • 1
    I'm in danger of vanishing up my own theories really on this one. I wish we could get a grammarian to cast an opinion. Dec 4, 2014 at 14:01

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