It's unfortunate that Stephanie's face wasn't captured at this moment because she would have no doubt been immediately struck by the psychological reaction known as fight or flight. Her brain would have just triggered the influx of a specific cocktail of hormones in order to prepare her to either stay and deal with a threat or try and run away to the safety. Stephanie chooses to fight. (It is from a video on interrogation of a murderer)

This usage of "would have" always confuses me because most sources only explain one usage of "would have" , which is forming a type 3 conditional sentence (For example: If it had rained, you would have gotten wet. ) . I know this is not a hypothetical conditional. It is something that really happened at that time in the past. I wonder why the narrator didn't usage past perfect instead of "would have + v3" ? " ...her brain had just triggered the..."

  • I do read it as a hypothetical: If her face had been captured, her brain would have triggered XYZ hormones. This doesn't really make sense until you realize that we can't say for sure whether this happened, because we don't actually have footage of her face at this time to confirm it. (I'm grasping a little to make the paragraph grammatically sound.)
    – randomhead
    Jun 22, 2021 at 18:29
  • 1
    Disagree. Stephanie likely was immediately struck by fight-or-flight, and her brain likely did trigger an influx of hormones. This isn't the unreal result of having her picture taken. It's the consequence of something that did happen earlier in the context.
    – gotube
    Jun 22, 2021 at 22:56

1 Answer 1


All modals have an epistemic meaning (about the speaker's knowledge or certainty) separate from their deontic one (about objective possibilities and obligations).

This one is epistemic: Her brain would have just triggered... means something like I conclude that her brain just triggered...

  • Thanks, is there any chance that you could provide me with a resource explaining this specific usage because I can't find it or could you elaborate on your answer? Jun 23, 2021 at 2:39
  • 1
    The speaker cannot assert that her brain triggered the influx (signalled directly by no doubt) but assumes or decduces that that is what happened. Epistemic must is more common, but "her brain must have triggered the influx ... " has the connotation of "I've just worked out or realised that ...". All modals can be used epistemically, and the would here has the nature of a natural and plausible conclusion.
    – Colin Fine
    Jun 23, 2021 at 19:28

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .