[Grammar] I would/could come, but ...

[NAL123]

Friend: John, can you come to the party tonight?

1) John: Sorry, no. I could come, but my mum is very ill and I have to take care of her.

2) John: Sorry, no. I could've come, but my mum is very ill and I have to take care of her.

3) John: Sorry, no. I would come, but my mum is very ill and I have to take care of her.

4) John: Sorry, no. I would've come, but my mum is very ill and I have to take care of her.

Q: Can I use the word "but" in this way with the modal verbs "could" and "would" to completely negate what has been said in the previous clause, instead of using any conditional markers like "if", "provided that", "otherwise" etc?

 

[jutfrank]

I'd like to come, but my mum's very ill and I have to look after her.

We do commonly use would before but. We often also use I would if I could in cases like this.

I would if I could, but my mum's ill so I have to stay in and look after her.

For me, 3 is fine. It seems a natural response to say:

I would come but I can't because I have to stay in and look after my mum.

It's like saying I would come if my mum were not ill, but she is ill so I can't.

 

[NAL123]

Thank you both!

Is there any possibility of (1) or (2) working in that context, for example, if I write them both like this:

1) John: Sorry, no. I could come if my mum were not ill.

2) John: Sorry, no. I could've come if my mum hadn't been ill.

3) John: Sorry, no. I could've come if my mum were not ill.

 

[jutfrank]

Don't ask whether there's "any possibility". That's not going to help clarify things.

The direct answer to your question is no, because from the context you've given, none of those are what you mean. What you mean is this:

I would come if my mum were not ill, but I can't.

One thing that I've gradually picked up from your repeated questions about possibility is that you want to use the word could to mean 'would be able to'. I'd strongly recommend you stop trying to do that. Remember that could can have both ability and possibility senses, which I think are confusing you. Get it clear in your mind which one of these two senses you mean.

If you want to talk about past ability, then could is fine. But if you want to talk about hypothetical ability, use would be able to, not could. I think this will be a good way for you to get things a bit clearer in your mind.

 

[NAL123]

One thing that I've gradually picked up from your repeated questions about possibility is that you want to use the word could to mean 'would be able to'. I'd strongly recommend you stop trying to do that. Remember that could can have both ability and possibility senses, which I think are confusing you. Get it clear in your mind which one of these two senses you mean.

Could you please give me one or two examples where the possibility sense of "could" is being used? I just want to see how this sense differs from the ability sense of "could".

 

[jutfrank]

Could you please give me one or two examples where the possibility sense of "could" is being used? I just want to see how this sense differs from the ability sense of "could".

That's a much better approach. Good. The best way into this is to first remove all sense of ability by entirely removing the human element. Here are two different situations:

You can imagine doing a sudoku puzzle, and asking yourself which numbers could possibly go in a certain box. You might say: It could be a 1 and it could be a 9, but it can't be a 5. In this case, the speaker is expressing logical possibility.

You could also imagine a scientist speculating on a particular matter, saying: It could be that the first living organisms evolved independently in different places—we just don't know. In this case, the speaker is expressing theoretical possibility.

Tell me if that's clear.

 

[NAL123]

You could also imagine a scientist speculating on a particular matter, saying: It could be that the first living organisms evolved independently in different places—we just don't know. In this case, the speaker is expressing theoretical possibility.

I think I found the theoretical possibility sense a bit difficult to understand. The "could" used there feels more like "might", as the sentence ends with "we just don't know": either this is the case or not.

 

[NAL123]

OK. Last question:

In (1) John: Sorry, no. I could come if my mum were not ill, apart from the ability sense of "could", which one of the two possibility senses you mentioned above is being suggested? (as you said in post #5, "would be able to" is not the only meaning of "could" being suggested in that sentence)

 

[jutfrank]

You tell me—what did you mean when you wrote the original example? Is John talking about ability or possibility or permission or what?

I've mentioned several times before the dangers of making up your own sentences and then trying to understand what they mean. That's really not the right way of going about this.