To my knowledge, both How could I...? and How could I have...? can be used to express disbelief at something you did in the past or you have just done. What could be the difference, if there is any?

1 Answer 1


could is for past ability. (We're not using it as a conditional clause.)

How could I do this? (I did it and I'm asking myself this.)

could have is for past possibility.

How could I have done this? (There was a way to do this, but I didn't, so I'm asking myself this.)

  • But couldn't we say, "How could I have done something so stupid?" when we really did/have done some insensible act?
    – goldbrick
    Commented Nov 27, 2015 at 17:27
  • If you did it, you use How could I do something so stupid?
    – Schwale
    Commented Nov 27, 2015 at 18:02

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