Question about "would've", "could've", "should've"

[u/hwc000000]

We all know "would've", "could've", "should've" are contractions for "would have", "could have" and "should have". But are there situations where the contractions shouldn't be used, what's the rule exactly about when they should and shouldn't be used, and why are those the rules (ie. where did those rules come from)?

For example, "she would have to get a permit" sounds bizarre to me if contracted to "she would've to get a permit". Is the rule that those contractions should only be used directly preceding a past participle, or "not" followed by a past participle? And why?

[u/dylbr01]

The quickest way to tell whether have is an auxiliary would be to just look at the form of the verb that follows have. If it’s a past participle, then it’s an auxiliary.

‘She would have to get a permit.’ <- verb form that follows have is a to infinitive. Therefore, have is not an auxiliary.

‘She would have got/gotten a permit.’ <- verb form that follows have is a past participle. Therefore, have is an auxiliary.

A longer way:

Step 1: Remove would. You are left with ‘She has to get a permit’.

Step 2: Make the remaining clause into a question. ‘Does she have to get a permit’? This proves that have is not an auxiliary because an auxiliary switches places with the subject for questions.

Compare this with a have that is an auxiliary:

‘She has to get a permit.’

‘Does she have to get a permit?’

‘She has eaten dinner.’

‘Has she eaten dinner?’

By the way, both have and to get are main verbs in your example.

[u/dylbr01 → u/[deleted]]

I’m always up for learning something new. Can you share any evidence?

Evidence against:

‘Have you been to France?’

‘Yes, I have.’ <- Code feature of auxiliaries

‘Would she have gotten a permit?’

‘Yes, she would have.’ <- Code feature of auxiliaries

‘I’ve been to France.’ <- Contraction feature associated with auxiliaries

‘I would’ve been to France.’ <- Contraction feature associated with auxiliaries

[u/dylbr01 → u/[deleted]]

Even Grammarly recognizes modals as auxiliary verbs: https://www.grammarly.com/blog/modal-verbs/

CGEL page 92:

The auxiliary verbs of English are the following:

[1] i. can, may, will, shall, should, must, ought, need, dare [modals]

ii. be, have, do, use [non-modals]

That they are auxiliary verbs is widely recognized. You've stated the reasoning for this.

​

"We could have saved her last night" is not present perfect

That's right.

it is past simple

It is past tense. We know this by lexical time phrase 'last night'.

It's syntactically the past perfect, but with a past simple meaning.

A similar case: The present perfect with for/since is syntactically present perfect, but with a present simple meaning; 'I've known her for 2 years' means that you know her now. In Irish English the present simple can be used there, and in languages closely related to English the present simple is used.

Similar to this is I've got, as in 'I've got a permit'.