From last lesson, at speed
One word per gap. Six sentences from the texts you read.
They have known — the announcement went out ten days after she left.
He have been planning it for weeks; you do not move country over a weekend.
I have said something at the time, and I said nothing.
You have brought a coat — it was twenty degrees all afternoon.
She have missed the train, or she may simply have overslept.
It have helped if two people had signed it off.
A scale nobody teaches
Certainty, and one strange asymmetry
The deduction modals form a scale, and English speakers treat it as surprisingly precise. She must have left claims the alternatives have been eliminated. She can’t have left claims the opposite, and just as firmly. She might have left claims almost nothing: one possibility among several, nothing ruled out. And she should have left by now sits between them — predicted by the evidence, and not yet confirmed.
Nobody is taught this and everybody hears it. Use must have where you meant might have and a listener will believe you have evidence you do not have; use might have where you meant must have and they will assume you are hedging for a reason. The scale is doing real work, and it is doing it whether or not you chose the position on it.
Then there is the asymmetry, which is the thing worth noticing today. The negative of must have is not mustn’t have. It is can’t have. English does not negate a deduction by adding not; it moves to the other end of the scale. He must have known becomes he can’t have known, and he must have not known is not something a speaker will produce.
The same happens out loud, and much more drastically. Have in a modal perfect is unstressed to the point of disappearing: should’ve is /ˈʃʊdəv/, must’ve is /ˈmʌstəv/, and couldn’t have comes out as three syllables with almost nothing in the middle. This is why should of is written by native speakers and by learners alike — it is an accurate transcription of the sound and a wrong transcription of the language.
Three questions.
1. What happens if you use must have where you meant might have?
2. What is the negative of he must have known?
3. Why is should of so common?
Two sets, and one reduction
System 1 · Deduction — how certain am I?
| Position | Form | What it claims |
|---|---|---|
| Certain, positive | must have | The alternatives have been eliminated, and this is what is left. She must have been planning it for weeks. |
| Certain, negative | can’t have · couldn’t have | Ruled out by something you know. He can’t have known — the announcement came later. |
| Expected | should have · ought to have | Predicted by the evidence, not yet confirmed. The parcel should have arrived by now. |
| Open | may have · might have · could have | One possibility among several; nothing eliminated. They might have forgotten. |
System 2 · Conduct — how did somebody behave?
| Form | What it claims | How it lands |
|---|---|---|
| should have · ought to have | You were obliged, and you did not do it. | A verdict. The default, and the one that arrives harder than it is meant. |
| could have | You had the opportunity, and you did not take it. | Sharper — it removes the excuse before it is offered. |
| might have | Indignant, and specifically British: you might have told me. | The sharpest of the three. Almost never used about anything but being kept in the dark. |
| needn’t have | You did it, and it turned out to be unnecessary. | Mild, usually generous. You needn’t have brought anything. |
| didn’t need to | It was not necessary — and you may well not have done it. | Neutral. Not a verdict at all, and not the same sentence as the one above. |
Out loud. Have is unstressed in every one of these, and it reduces to /əv/ or disappears into the modal.
should’ve /ˈʃʊdəv/ · must’ve /ˈmʌstəv/ · might’ve /ˈmaɪtəv/ · couldn’t have → couldn’t’ve, three syllables with almost nothing in the middle.
Say the participle at full length and let the auxiliary go: I should’ve GONE. A stressed have turns the sentence into a contradiction — I should HAVE gone answers somebody who has just said you should not have.
And in writing it is have, always. should of is an accurate transcription of the sound and it is not a word.
Rewrite each sentence using the word given, keeping the meaning the same.
I am certain she was planning it for weeks. MUST
It is impossible that he knew about the restructure. HAVE
Perhaps they forgot to send it. MIGHT
It was a mistake not to tell the team. SHOULD
You had the chance to warn me and you did not take it. COULD
She brought her passport and nobody so much as looked at it. NEEDN’T
I am not blaming anybody; the process was missing a second check. HELPED
The parcel was posted on Monday, so I expect it has arrived. SHOULD
Five questions.
1. The negative of he must have known is…
2. Should’ve written out in full is…
3. She needn’t have brought her passport means…
4. She didn’t need to bring her passport means…
5. You might have told me is…
Somebody has moved the figures
Eight gaps. Choose the form that fits the evidence the writer has.
The figures in the shared file were different on Tuesday morning from how I left them on Monday night, and only four people have access. It me, because I was on a train with no signal from six until ten. It Dan, who edits everything and apologises afterwards, but he was on leave. So it either Priya or the finance team, and the finance team — they had asked for exactly this change on the Friday and been told to wait.I locked the file, obviously, and I did not, because in eleven years nobody has ever edited anything of mine without saying so. Priya, when I asked her, said she bothered mentioning it because it was a two-cell change, which is fair, and I made quite as much of it as I did. What I said in the end was that it if the file had had a change log, which it now has.
Six lines of one deduction, out of order. Put them into the order that reasons.
- It might have been one of the contractors, though they usually ring first.
- So the log was right and my reasoning was wrong in every single particular.
- Somebody must have opened the building before seven, because the alarm log says so.
- She needn’t have come in at all, as it happens — the meeting had already been moved.
- It can’t have been the cleaners; they do not come in on a Wednesday.
- In the end it turned out to be Nadia, who had left her laptop on the Tuesday.
Place it on the scale
Task card · Speaking · Pairs · 8 minutes
A colleague who has been reliable for four years has missed two deadlines and has stopped coming to the Monday meeting. Nobody has said anything to them.
Four minutes generating explanations, four placing them — and one sentence at the end that is not a verdict.
- 4 minutes: generate at least eight explanations. Anything at all — the point is quantity, not plausibility.
- Then place each one on the scale out loud, with the right modal: ruled out (can’t have), open (might have), or forced by something you actually know (must have).
- Be honest about the evidence. If nothing has been eliminated, then nothing takes must have, however confident you feel.
- Finish with one sentence you could actually say to them, using none of the conduct modals. It would have helped if… is one way in.
Where the evidence ran out
Two questions.
1. How many of your explanations genuinely deserved must have?
2. What did the final sentence sound like without a conduct modal?
/əv/, and the other end of the scale
Two questions. Twenty seconds.
1. How does English negate a deduction?
2. Which word carries the stress in I should’ve gone?
Next. The moment somebody hears the wrong system — and the three frames that let you say the same thing without handing out a grade.