The Present Perfect for general statements

[Alexey86]

I'd use different words to express the other idea: He wasn't capable of doing it, for example.

Thank you! Then, how would you distinguish speaker's confidence in the low probability (not the physical impossibility) of an event/action from the expression of great surprise?

 

[abaka]

Here's how I'd sum it up:

1. "He can't have done it" refers to an absolutely real situation: someone has already done it, but under the present circumstances, he cannot be the culprit.

2. "He couldn't have done it" dismisses the possibility of him being the culprit under any possible circumstances.

Both express the surprise of the speaker.

(2) is completely commonplace, but for whatever reason (1) is cultivated -- or regional. It sounds perfectly fine to my Canadian ears.

 

[Alexey86]

Thank you for summing that up. Can you think of any situation in which you would use "can have done"?

 

[Alexey86]

I gave you a link to 32 examples in post #21.

I've looked them up, thank you. But it's not clear to me why they use "can have done" instead of "can do" ("I want to know if there is anything else I can have done now to make me look pretty.") or "could have done ("There are few people in the history of the world that can have done more than Mohammed Yunus…", or "...providing pictures isn't really proof because you can have done something before taking them.").​

 

[abaka]

"Have done it" is necessary if and only if someone has already done it. If my Russian is correct, "delo sdelano".

"He can have done it" means that it is possible for him to have done it in the present circumstances. "Vozmozhno, on eto sdelal".

"He could have done it" means that it is possible for him to have done it under some circumstances, not necessarily the present ones. "V printsipe, on na eto sposoben".

For "do it", there is no necessity for it already to have been done. "Esche net sostava prestupleniya".

"He can do it" means he has the physical ability to peform the action. "On na eto sposoben".

"He could do it" means that for him to do it, a specific set of circumstances are necessary. "On eto sdelaet, esli..."

If there are errors in my Russian, please excuse them. It's been a very long time since I studied the language. Dear mods, if I shouldn't introduce foreign analogies in a forum devoted to English, please let me know. :-D

 

[jutfrank]

Re: post #20

Alexey—Thanks for going to the trouble of quoting the Quora responders. I see where you're reading from now. I was looking only at the first 7 answers, of which 1 says the form can have done is "illogical", one says it's "incorrect", 4 say it works, and 1 seems to miss the question entirely.

Unfortunately, all of those who say that can have done is incorrect or illogical are very much mistaken.


Again, your original sentence:

One can have known someone for a long time and yet not know their age.

A way to rephrase this is:

It is possible for one to have known someone for a long time and yet not know their age.

 

[jutfrank]

Does "can have done" sound fine to your ears? Do you hear or use such a construction in your everyday conversations?

It's literary language -- high style, very cultivated speech.

abaka—I find it very interesting what you've said here because I very much disagree.

I wonder if there's a difference of variety (BrE/NAmE) going on here. (See GoesStation's post #10). I really can't imagine how that could be.

If there is a varietal difference, could you suggest how a NAmE speaker might say the original sentence, as shown in post #29 above?

 

[abaka]

Jutfrank -- I think my Canadian ears are caught between the British and American usage. "Can have done" is certainly not something you hear every day in Canada. It gives off a literary air, a phrase a fastidious writer might use -- or, indeed, something redolent of imagined British middle class afternoon tea. But it's not wrong or in any way weird, and once you start thinking about it, it's easy to draw the semantic distinctions I've outlined above.

But Canadian English is a funny thing. It sounds perfectly broadcast-American, but it isn't. A smattering of native vocabulary aside (chesterfield, hoser, keener, or two-four, as in "two-fours on May two-four"), I think in many ways it maintains the old-fashioned imperial usages of c. 1900. Look at our spelling, for example: always colour and centre, but also always realize. And the more polished our language, the more old-British it becomes. Until about 1990, our CBC radio news were delivered with an RP-like pronunciation called "Canadian dainty", and certainly even in the 1970s all schooling strongly emphasized the imperial/Commonwealth past.

I know that's a long digression to explain why I've said that this phrase is "cultivated -- or regional". :-D

All the suggested replacements are fine as well, really.

 

[Alexey86]

"He can have done it" means that it is possible for him to have done it in the present circumstances. "Vozmozhno, on eto sdelal"." He could have done it" means that it is possible for him to have done it under some circumstances, not necessarily the present ones. "V printsipe, on na eto sposoben".

Abaka, thank you for your Russian analogies. Here’s how I see the whole picture so far:

past/or a remote place--------{”it”--"he"--now/here}---------future => He can have done it.
{past/a r.p.--”it”}--------------{”he”---now/here}-------------future => He could have done it.
{past/a r.p.--"he"}-------------{"it"----now/here}-------------furute => He could have done it.

If we imagine several suspects at a crime scene one of which has blood on his hands, it would be reasonable to assume, “He can have done it.” But if we are just speculating about various people, we’d rather say, “He could have done it” about one of them.
Correct me if my understanding is wrong.


Piscean gave me a link with some examples of using “can have done”. What do you think about these particular ones:

1. "I want to know if there is anything else I can have done now to make me look pretty." Why not “I can do now”?

2."There are few people in the history of the world that can have done more than Mohammed Yunus…". Why not “could have done”?

 

[abaka]

Your scheme shows I've got my point across.

In (1), the speaker is stressing the fact she's already made great efforts to make herself pretty. "Can do" would mean the same thing, but she'd be looking forward rather than back.

In (2), Yunus has already made great efforts, and in the real historical circumstances he has faced, few can/could do more.

 

[Alexey86]

Your scheme shows I've go my point across.

What do you think if I add one more line related to general statements? I'm not sure I depicted it correctly.

{timeless past----timeless present-----action/event}------future => One can have known someone for a long time and yet not know their age.
past/a remote place---------{”it”--"he"--now/here}--------future => He can have done it.
{past/a r.p.--”it”}--------------{”he”---now/here}----------future => He could have done it.
{past/a r.p.--"he"}-------------{"it"----now/here}----------furute => He could have done it.

 

[abaka]

Alexey, if the scheme helps you construct correct sentences in context, go ahead and use it. But I must say I've never really thought of anything being "timeless". I suspect strong grounding in time is essential in the Anglophone mindset.

 

[Alexey86]

Maybe "timeless" isn't the right word, and "indefinite" is more suitable. Thank you anyway.

 

[abaka]

It is quite correct to use "indefinite" and "perfect" as the two aspects. I think "remote" tends to suggest some kind of past perfect, which is not at play here. But if the terms you use help you, go ahead.

 

[jutfrank]

Let me attempt to answer your questions in post #32 in a general way.

1. "I want to know if there is anything else I can have done now to make me look pretty." Why not “I can do now”?

Quite simply, using can do would not provide the retrospective aspect that can have done has, which places a focus on the past. (See post #33.)

2."There are few people in the history of the world that can have done more than Mohammed Yunus…". Why not “could have done”?

This question, which can ultimately be generalised to the differences between can and could, deserves its own thread, in my opinion. Both can and could are used to express ways of thinking about possibility, but there are key differences of meaning/use between them.

The use of present tense can in this sentence effectively places the possibility in the present, providing a somewhat more general, and 'theoretical' possibility than could. Very generally speaking, we tend to talk about facts and theories about the world in the present tense.

You might rephrase the thought as:

It is theoretically unlikely to be true that anyone has done more than Mohammed Yunus.

In contrast, using past tense could instead would effectively place the possibility in the past. Another way to phrase this new sentence, then, might be:

It was not possible in the past for many people to have done more than Mohammed Yunus.

I don't think that is what the writer wants to say.

 

[Alexey86]

Thank you for your detailed response. What could be the answers to the question #1 "I want to know if there is anything else I can have done now to make me look pretty."? => a) You can have done X to make you look pretty. b) You can't have done more to make you look pretty. c) You can have done nothing more/else.

As I see, "b" might be ambiguous since this negation might convey the meaning of great surprise.

 

[GoesStation]

What could be the answers to the question #1 "I want to know if there is anything else I can have done now to make me look pretty."? => a) You can have done X to make you look pretty. b) You can't have done more to make you look pretty. c) You can have done nothing more.

As I see, "b" might be ambiguous since this negation might convey the meaning of great surprise.

The sentence doesn't use can have done in the way this thread is discussing. It's using the causative can to talk about various things you can direct somebody to do in order to make you more attractive.

 

[emsr2d2]

Thank you for your detailed response. What could be the answers to the question [STRIKE]#1[/STRIKE] "I want to know if there is anything else I [STRIKE]can[/STRIKE] could have done [STRIKE]now[/STRIKE] to make [STRIKE]me[/STRIKE] myself look pretty?" [STRIKE]=>[/STRIKE]
That's not a question. It starts with "I want to know" so it's just a statement. To make it a question, use "Is there anything else I could have done to make myself look pretty?"

a) You [STRIKE]can[/STRIKE] could have done X to make yourself look pretty.
b) You [STRIKE]can't[/STRIKE] couldn't have done more to make yourself look pretty.
c) You [STRIKE]can[/STRIKE] could have done nothing more/else.

As I see it, "b" might be ambiguous since this negation might convey the meaning of great surprise.

See above. Unfortunately, "can" did not fit any of your sentences. I don't understand the part in blue.

 

[jutfrank]

What could be the answers to the question #1 "I want to know if there is anything else I can have done now to make me look pretty."? => a) You can have done X to make you look pretty. b) You can't have done more to make you look pretty. c) You can have done nothing more/else.

As I see, "b" might be ambiguous since this negation might convey the meaning of great surprise.

I don't feel I can answer this reliably without seeing more context. (If you can be bothered to find it, I'll happily attempt an answer.)

It's just that I don't fully understand what the situation is or what the speaker is thinking exactly. Above all, I wonder why she uses the word now, which seems to me out of place. Since the word now at least appears to be emphasising a time frame, I suspect that its inclusion in the utterance is significant.

It's also not clear to me why she has chosen to frame the sentence in the present tense (using is/can) as opposed to the past tense (was/could).

 

[Alexey86]

Thank you for your corrections. I understand that syntactically this sentence is not interrogative, it just sounds like an indirect request.

I don't understand the part in blue.

For example, "You can't have done it" might mean "I'm so shocked that refuse to believe you did it". GoesStation mentioned above that I confused this construction with the causative can, but I don't quite understand what it means. Does he mean that "can have done something" and "can + have something done" (like in "I have my car washed every Sunday" -> "I can have my car washed every Sunday") are different constructions?

If so, then "I want to know if there is anything else I can have done now to make myself look pretty" might mean "I had X done, and I had Y done. But I'm still not happy. Now I can have anything else done, but I have no idea what it might be."