how could he have been so stupid?

[Bambook]

It is from Harry Potter - "Quirrell’s voice tailed away. Harry was remembering his trip to Diagon Alley – how could he have been so stupid? He’d seen Quirrell there that very day, shaken hands with him in the Leaky Cauldron."

My question. Is it possible to replace "could he have been" with "could be" but not to loose the right meaning?
As to my my knowledge "could have been" is used to show unreal situation = for things which did not happened.
But in that sentence the situation was real. So I would say "how could he be so stupid?".

2. Seraching the internet for unswers to my question I came across with this page https://englishwithjennifer.wordpress.com/2015/07/23/student-stumper-42-could-do-vs-could-have-done/
My question is about this line. "I knew I couldn’t have missed the exit. [a past impossibility with “couldn’t have missed” being placed before “knew” on a timeline]" You see the author is giving comments in brackets. So my question is about the comments. About this - "placed before “knew” on a timeline". So It looks that you are using structures like this "I knew I couldn’t have missed the exit" to show that one event happened before the other. Is it so? And is this the case here? I know only that past perfect is used for that. And I would say "I knew I had not missed the exit".

 

[5jj]

"could have been" is used to show unreal situation = for things which did not happened.

Not necessarily. It suggests a degree of likelihood - or lack thereof.

1. It was difficult to judge her age; she could have been anywhere between thirty and sixty.
2. If she hadn't referred to Trump supporters as 'deplorables', Hillary Clinton could have been the first female President of the USA.

1. She was between thirty and sixty.
2. She was not the first female President of the USA.

 

[emsr2d2]

It The following is from one of the Harry Potter books by J K Rowling:
"Quirrell’s voice tailed away. Harry was remembering his trip to Diagon Alley – how could he have been so stupid? He’d seen Quirrell there that very day, shaken hands with him in the Leaky Cauldron."

My question. Is it possible to replace "could he have been" with "could be" but not to loose without losing/changing the right meaning?
As To my my knowledge, "could have been" is used to show unreal situations, ie for things which did not happened happen.
But However, in that sentence the situation was real no full stop here so I would say "how could he be so stupid?" no full stop here

2. Seraching Searching the internet for unswers answers to my question, I came across with this page:

https://englishwithjennifer.wordpress.com/2015/07/23/student-stumper-42-could-do-vs-could-have-done/

My question is about this line: "I knew I couldn’t have missed the exit. [A past impossibility with “couldn’t have missed” being placed before “knew” on a timeline]"

You see The author's is giving comments are in brackets. So My question is about the comments, specifically about this one: "placed before “knew” on a timeline".

So It looks that like you are using English uses structures like this "I knew I couldn’t have missed the exit" to show that one event happened before the other. Is it so that right no full stop here and is this the case here? I know only that the past perfect is used for that no full stop here and I would say "I knew I had not missed the exit".

Please note all my corrections above. As a learner, don't try to start sentences with "and" or "but", and please avoid opening with "so" completely.

Please complete the source information by telling us which of the Harry Potter books the quote is taken from.

 

[Bambook]

Please complete the source information by telling us which of the Harry Potter books the quote is taken from.

It is from HARRY POTTER and the Philosopher’s Stone. CHAPTER SEVENTEEN - The Man with Two Faces.

And thank you for corrections!

 

[emsr2d2]

It is from HARRY POTTER "Harry Potter and the Philosopher’s Stone", CHAPTER SEVENTEEN chapter seventeen - The Man with Two Faces.

And thank you for your corrections!

 

[jutfrank]

Yes, it's about a real past history (he really was that stupid) but the idea is to question whether that past reality is really possible because it's so against Harry's character that it's hard to believe. The rhetorical effect of this is to suggest that what really happened is seemingly impossible.

How could he have been so stupid? = How is it possible that there is a past reality where he was as stupid as he was, given that he isn't usually that stupid?

 

[Bambook]

Is it so that here Harry is trying to lessen or justify his fault by saying "... could he have been ...", whereas by saying "How could he be so stupid?" he would have admited his fault directly.

 

[jutfrank]

No.

 

[Bambook]

No.

If I ask this way. Is phrase "How could he be so stupid?" also possible for the case discussed?

 

[jutfrank]

Which case? The Harry Potter excerpt?

The 'have been' part, unlike the simple 'be' that you suggest, casts what we call a perfect aspect. In this context, the perfect aspect places Harry's stupidity clearly in past time.

 

[emsr2d2]

Is it so that here Harry is trying to lessen or justify his fault by saying "... could he have been ...", whereas by saying "How could he be so stupid?" he would have admitted his fault directly?

No. He's clearly admitting that he recognises that he was stupid when he did what he did. He's not saying he is stupid or that he is being stupid now.

 

[Bambook]

Which case? The Harry Potter excerpt?

Yes.

The 'have been' part, unlike the simple 'be' that you suggest, casts what we call a perfect aspect. In this context, the perfect aspect places Harry's stupidity clearly in past time.

Is phrase "How could he be so stupid?" also possible here? Is it understood as action in the past?

 

[emsr2d2]

Yes.

Is phrase "How could he be so stupid?" also possible here? Is it understood as action in the past?

Please read all our responses again. The answer to your question has already been stated.

 

[Bambook]

Please read all our responses again. The answer to your question has already been stated.

I have read them again. I can not see it. Please point it.

 

[jutfrank]

Is phrase "How could he be so stupid?" also possible here? Is it understood as action in the past?

The reader would understand that it's about the past, yes, because of the preceding context:

Harry was remembering his trip to Diagon Alley—

 

[Matthew Wai]

Please point it.

Do you mean "point it out"?
Reference: https://www.ldoceonline.com/dictionary/point-out