Question tag —You could buy a new one...

[man of manners]

Hi!
This is a new thread in which we will discuss some sentences that need suitable question tags.
The sentence is:
I have a good suggestion. You could buy a new one,...............? [the context is about 'suggestion']
My opinion: "will you/won't you/can't you?".

Thanks in advance!

 

[teechar]

You could buy a new one

I wonder why "couldn't you" is not on your list.

 

[man of manners]

I wonder why "couldn't you" is not on your list.

Because the construction "You/We could...." is idiomatic when used in the context of suggestion. Here "could" doesn't refer to the past but the future. If we used "couldn't", it is not idiomatic anymore [we cannot use "You/We couldn't..." for suggestion] so the meaning would be destroyed and "could" would refer to the past, which conflicts with the context given.
Now, what should be used in your opinion?

 

[teechar]

I don't fully understand what you're trying to say, but the short answer is that I would definitely use "couldn't you" in the original. It's natural and idiomatic in that context.

 

[man of manners]

I am pretty sure you understand me but you are trying to use an identical modal verb to the one used in the original sentnece as most of the British do, but be sure that the meaning does change.
"could" is used in the idiomatic expression "You/We could..." for the meaning of "suggestion" and any changes in this idiomatic expression [using "couldn't" in the negative form for example] leads us to not understanding the meaning properly. The use of "couldn't" in the question tag just doesn't work. Some people wouldn't even think of the meaning given in the question tag so the use of "couldn't" can be acceptable.
If you still don't get it, I will give your another example:
"must" when used for "deduction" can be tagged as "mustn't" despite the fact that "mustn't" doesn't work for deduction.
I hope you got it.

 

[teechar]

I am pretty sure you understand me but

Unless you're a mind reader, I don't know how you can assert that!
It's also not very mannerly of you, is it?

 

[SoothingDave]

I am pretty sure you understand me but you are trying to use an identical modal verb to the one used in the original sentnece as most of the British do, but be sure that the meaning does change.
"could" is used in the idiomatic expression "You/We could..." for the meaning of "suggestion" and any changes in this idiomatic expression [using "couldn't" in the negative form for example] leads us to not understanding the meaning properly. The use of "couldn't" in the question tag just doesn't work. Some people wouldn't even think of the meaning given in the question tag so the use of "couldn't" can be acceptable.
If you still don't get it, I will give your another example:
"must" when used for "deduction" can be tagged as "mustn't" despite the fact that "mustn't" doesn't work for deduction.
I hope you got it.

Since you know all of the answers, I wonder why you are here asking questions. Are you somehow convinced that "most of the British" (and we Americans, too) are incorrect?

 

[man of manners]

I don't know how you can assert that!

My explanation is here for you to consider not to discuss impolitely.

It's also not very mannerly of you, is it?

What exactly is not polite in what I said?!!
You have showed me enough of your good manners!

 

[man of manners]

Since you know all of the answers

I do not. Please, do not make me look as if I said this.

I wonder why you are here asking questions.

I ask for answers sometimes and ask for confirmation as well.

Are you somehow convinced that "most of the British" (and we Americans, too) are incorrect?

No, of course. I am adding another possible answer and asking for conformation.

 

[Barb_D]

The use of "couldn't" in the question tag just doesn't work. Some people wouldn't even think of the meaning given in the question tag so the use of "couldn't" can be acceptable.

You are utterly incorrect. No one will confirm your understanding, because your understanding is wrong.

The idiomatic tag is "couldn't you?"

If this thread works as your others have, you will protest and disagree and every single native speaker will tell you that you're not correct, but you will continue to protest and disagree. So forgive me, but this will be the last post I make in this thread, because there is absolutely nothing you can post that will change my mind about "couldn't you?"

 

[GoesStation]

I have a good suggestion. You could buy a new one,...............? [the context is about 'suggestion']
My opinion: "will you/won't you/can't you?".

The pattern is You could buy a new one, couldn't you? It doesn't matter whether you're thinking about suggestions or platypuses; the verb in the question tag matches the one in the preceding statement.

 

[Skrej]

Perish the perplexing possibility perhaps, but I haven't perchance pondered the platypus in a coon's age.

 

[Tdol]

I'm just curious, but what drives your fascination with question tags? There are plenty of borderline cases with question tags, but in thirty years of teaching I have never come across someone this interested in them.

 

[man of manners]

I'm just curious, but what drives your fascination with question tags? There are plenty of borderline cases with question tags, but in thirty years of teaching I have never come across someone this interested in them.

I have a lot of question on various aspects of grammar, not only question tags.

There are plenty of borderline cases with question tags

Like what?

 

[emsr2d2]

I have a lot of question on various aspects of grammar, not only question tags.

Maybe you could give us a little rest from this particular aspect and ask a few questions about the other aspects which confuse you.

 

[man of manners]

Maybe you could give us a little rest from this particular aspect and ask a few questions about the other aspects which confuse you.

OK, I do not mind at all.

 

[Tdol]

Like what?

Like a number of the questions you have asked so far. ;-)

 

[man of manners]

Like a number of the questions you have asked so far. ;-)

Did you know them before I asked about them here?

 

[Rover_KE]

We would have had no reason to think about them before you asked.

 

[Matthew Wai]

I advise the OP simply not to use a question tag in borderline cases, or he would simply complicate things for himself.