If they’re following their schedule, they will have arrived yesterday.

Yesterday? But yesterday is not a part of the future? I'm confused now.


4 Answers 4


This is a confusing sentence, but I would interpret the "will" here as meaning "must" rather than literally referring to the future. "They must have arrived yesterday."

  • Do you think the sentence is controversial? I don't find it grammatical. Jun 17, 2019 at 6:59
  • 1
    No, it seems pretty natural. In fact, I'm not sure how else you would express it without subtly changing the connotation. Written this way, it sounds like you are very confident they did arrive yesterday, based on the schedule.
    – Ethan B.
    Jun 18, 2019 at 12:40
  • To elaborate, it's a confusing sentence when you try to think of how it works grammatically (at least for me, not being trained in English language education), but it doesn't sound that weird.
    – Ethan B.
    Jun 18, 2019 at 12:42
  • Are you saying the sentence might not be grammatical? Jun 18, 2019 at 15:34
  • 1
    Yes, this kind of sentence is common. LIke all modals, will can have an epistemic meaning as well as a deontic one. Its deontic meaning often refers to the future, which is why expressions using will are so often mis-characterised as a "future tense". This is an example which requires an epistemic reading.
    – Colin Fine
    Mar 22, 2022 at 22:43

I doubt anyone can "will" a traffic delay which is inclined to mean intent, deliberate, with a mental control

But a natural consequence, if nothing goes wrong, ought to use "would".

If they’re following their schedule, they would have arrived yesterday.


will here is to be taken in the sense of then it must surely be the case that

Their presence upon arrival is the "result in the present" which concerns the speaker most, triggers the construction with have, even though yesterday would otherwise trigger a simple past tense.


No. No one can arrive yesterday in the future. Will denotes what is in the future. I cannot plan on arriving yesterday. I could have though. I could have arrived yesterday but I cannot arrive yesterday. I can have arrived yesterday.

  • That depends on what the author wanted to suggested. While not logically possible, I don't see a problem with it grammatically. Just think of it as a construction from a novel about time travel, and the sentence becomes a lot more reasonable.
    – Joachim
    Sep 2, 2022 at 21:10

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