This is from the BBC where a mom, whose daughter has a phobia of talking, tells about her feelings. Phobia of Talking (See:4:49-4:54)

"....Why didn't you notice it. Why couldn't I have done more?"

Her using "couldn't have done" drew my attention, because that structure seems to have another meaning (strong impossibilty). For instance, "He could not have burgled the house, because he was at the party last night."

So, I wonder why she didn't simply use "couldn't do" as in "Why couldn't I do more?",, because "could" very well fits in this situation, where you are asking the reason for someone failing to do something the past. For example, if somebody failed an exam last year, you would say:

A: "Why couldn't you pass the exam last year.?"

B: "Because I did not study."

As you see, you wouldn't say "Why couldn't you have passed the exam last year?"

So, finally, if this usage is correct, I wonder if "...couldn't have done..." is simply an alternative to "...couldn't do..." in this situation?

  • 1
    "Why couldn't I have done more?" seems totally idiomatic to me. It maybe emphasises that it was in the past (drawing a distinction with the present) more than "Why couldn't I do more?"
    – Stuart F
    Sep 25, 2023 at 9:55
  • Nobody ever asks Why could not you pass the exam last year? Rarely, you might encounter the (rather "affected") full form Why could you not pass the exam last year?, but we nearly always contract (with the negation attaching to could, not pass) as Why couldn't you pass the exam last year? Sep 25, 2023 at 11:25
  • The sentence is correct and doesn't need to be fixed. I have no idea why you think it isn't idiomatic. It is completely natural. The interviewer asks "Do you feel you could have done more?", and she then questions herself asking "Why couldn't I have done more" - a rhetorical question. The implication is that she was unable to do so, because she didn't know what was wrong. She continuous "But if I had known . . . I would have . . . "
    – Billy Kerr
    Sep 25, 2023 at 11:41
  • @BillyKerr, I thought so, because in grammer lessons, we were taught that "couldn't have done" is used when the likelihood of a past possibility is nearly impossible (very strong guess). For instance; A: "He could not have stolen the wallet. B: Why couldn't he have stolen it? A: Because he was sleeping at that time." As you see, the structure "couldn't have done" gives the strong impossibility. And the sentence "Why couldn't I have done more?" does not refer to such an impossibility. So, I wanted to make sure if "...couldn't do..." and "...couldn't have done..." are the same in this context.
    – Yunus
    Sep 25, 2023 at 15:22
  • @BillyKerr, yes very well explained now. Thanks. I am happy that I have learnt this usage, too, which is yet another one for me and which we were never taught at school. I wonder how many more such different usages of seemingly known things are out there waiting to be discovered by us, non-native speakers and learners :)
    – Yunus
    Sep 25, 2023 at 18:43

1 Answer 1


The Simple Past enquiry...

1: Why couldn't you do that yesterday?

...more naturally suits contexts where the speaker genuinely wants to know why you weren't able to do it then. But there's usually a different emphasis with Present Perfect...

2: Why couldn't you have done that yesterday?

...because Present Perfect draws attention to the connection between a past action and the current time of speaking. Most often the meaning of that implied connection is...

2a: You should have done it yesterday!

Hence #2 above is often a rhetorical question. The speaker isn't interested in being given a reason / excuse - he just wants to berate you for not doing (having done :) it yesterday.

  • yes that was the point I was looking for an answer. You just put your finger on the point even before I asked it clearly. I always thought that "Why couldn't you do that yesterday?" and "Why couldn't you have done that yesterday?" have completely different meaning, and now I understand that "....couldn't have done..." is the rhetorical version of "....couldn't do....", which were never taught at school. I also wonder why in the preceeding sentence she says "Why didn't you notice it." If she is using rhetorically, why doesn't she say "Why couldn't you have noticed it"?
    – Yunus
    Sep 25, 2023 at 15:31
  • "Why didn't you notice it yesterday?" could well be a genuine inquiry implying no criticism. But with "Why couldn't you have noticed it yesterday?" it's almost a certainly that the speaker is complaining that the addressee should have done it yesterday. Sep 25, 2023 at 18:16

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