would have done = must have done = will have done?

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unbknnt

Senior Member
Russian - Russia
Hello!

In one textbook for those striving for proficiency in English (Longman Exam Skills: New Proficiency. Use of English) I often come across the use of would + Perfect Infinitive in the sense of a logical assumption or strong hypothesis. It runs a bit counter to its much more common use as a means of expressing an unreal, imaginary situation (within Conditional 3) and what many other textbooks say about it, so I thought I should turn to native speakers for commentary.

I would very much appreciate your help with this!

1) Is this meaning actually present in "would" and in any noticeable way used in speech and writing (since this seems to be my first encounter with it)?
2) Is it, consequently, the Indicative Mood, not the Conditional one?
3) If so, is there any difference in this sense between must/would/will like in the following phrases:

He must have been cooking yesterday at 6.
He would have been cooking yesterday at 6.
He will have been cooking yesterday at 6. (Here will also expresses not futurity, but acts as a modal verb, which appears to be a rare thing, though more common than "would" in the similar sense.)

For more concrete examples, in all the highlighted gaps below the answer key of the textbook suggests must/would have +V3.

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  • Keith Bradford

    Senior Member
    English (Midlands UK)
    Have you looked here: would be = is?

    I think the answer has to be, no this is not the indicative mood. Would is always in some way conditional, even if the condition is merely "if you believe my answer". It's a typically English form of modesty.
     

    PaulQ

    Senior Member
    UK
    English - England
    Would expresses two ideas:
    1. The past tense of will - "I will go to London" -> "He said he would go to London."
    2(a) A tentativeness, usually used for polite requests: "Would you help me, please?"
    2(b). A degree of probability - "If you use fertilizer they would grow better." -> "If you use fertilizer, they probably will grow better."
    2(c) A generality cause by habit - "Each morning he would take the do for a walk."

    You will see that the second idea always encompasses a level of uncertainty: 2(c) is "uncertain" because all generalities are uncertain.
    In 2. would is best seen as a tenseless modal verb of probability, which is independent of the modal "will".

    In general, all the modals follow this pattern:
    "Putting fertilizer on the plants can work." -> is certainly able to have the desired effect.
    "Putting fertilizer on the plants could work." -> is possibly able to have the desired effect.
     

    unbknnt

    Senior Member
    Russian - Russia
    Would expresses two ideas:
    1. The past tense of will - "I will go to London" -> "He said he would go to London."
    2(a) A tentativeness, usually used for polite requests: "Would you help me, please?"
    2(b). A degree of probability - "If you use fertilizer they would grow better." -> "If you use fertilizer, they probably will grow better."
    2(c) A generality cause by habit - "Each morning he would take the do for a walk."

    You will see that the second idea always encompasses a level of uncertainty: 2(c) is "uncertain" because all generalities are uncertain.
    In 2. would is best seen as a tenseless modal verb of probability, which is independent of the modal "will".

    In general, all the modals follow this pattern:
    "Putting fertilizer on the plants can work." -> is certainly able to have the desired effect.
    "Putting fertilizer on the plants could work." -> is possibly able to have the desired effect.
    Thank you!

    Ok, then, can I change "will" in the phrases below for "would" without any significant shift of meaning?
    Will it decrease the expressed probability, certainty?

    Call Mike, he will be at home now. (=he is probably at home)

    Call Mike, he will be cooking now. (=he is probably cooking)

    Call Mike, he will have made dinner by now. (=he has probably made dinner)

    Call Mike, he will have been cooking all day. (=he has probably been cooking all day)


    And are the sentences below approximately equal in terms of expressed meaning or at least grammatical?

    I believe when you called Mike he will/would have been tired. (=he must have been…)

    I believe when you called Mike he will/would have been cooking. (=he must have been…)
     

    PaulQ

    Senior Member
    UK
    English - England
    Ok, then, can I change "will" in the phrases below for "would" without any significant shift of meaning?
    By definition, changing will to would changes the meaning.

    However, some of your examples are poor and illogical as they imply that Mike should be called when he will be busy doing something.

    All of them start with an imperative - that implies that what follows, as a reason, is true, not merely a possibility.

    The use of "would" in the conditional to express uncertainty is logical as the condition must be fulfilled in order that the conclusion be valid.
    And are the sentences below approximately equal in terms of expressed meaning or at least grammatical?
    I believe when you called Mike he will/would have been tired. (=he must have been…) = it is probable that he was tired. (In order to use "will", you would need additional, relevant context
    I believe when you called Mike he will/would have been cooking. (=he must have been…) = it is certain/probable that he was cooking
     

    unbknnt

    Senior Member
    Russian - Russia
    By definition, changing will to would changes the meaning.

    However, some of your examples are poor and illogical as they imply that Mike should be called when he will be busy doing something.

    All of them start with an imperative - that implies that what follows, as a reason, is true, not merely a possibility.

    The use of "would" in the conditional to express uncertainty is logical as the condition must be fulfilled in order that the conclusion be valid.


    I believe when you called Mike he will/would have been tired. (=he must have been…) = it is probable that he was tired. (In order to use "will", you would need additional, relevant context
    I believe when you called Mike he will/would have been cooking. (=he must have been…) = it is certain/probable that he was cooking
    Thank you for your patience, I see the options you mark as correct and incorrect, but I can't get the distinguishing principle.

    What's wrong with "I believe when you called Mike he will have been tired/must have been tired."? Must implies a very high degree of certainty and is a bit at odds with "I believe", yet it still seems acceptable if we are sure about what be believe to be true. As for "will" when describing assumptions about the past, what is its difference from would in the same function? What context would justify its use, then?

    So, in general, what kind of assumptions do we describe with will and what with would when speaking about present/past? How to draw at least a vague line between the appropriateness of the 1 option / inappropriateness of the 2 one?
     
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