Will/Shall + perfect infinitive

Question

Could you shed some light on the issue. When we have Will/Shall as modal verbs with perfect infinitive how can we distinguish when we mean the future or the past. For example

He won't have done it! (Does it have the future meaning or the past meaning?)

CalifJim · Accepted Answer

Ticcehow can we distinguish when we mean the future or the past.

Add adverbs of time -- typically an expression with "by".

He won't have done it by now. (I strongly doubt that he has already done it.)

He won't have done it by tomorrow. (I strongly doubt that he will already have done it before tomorrow.)

A little unusual, perhaps, but possible:

He won't have done it by yesterday. (I strongly doubt that he had already done it before yesterday.)

CJ

Ticce · Answer

Jim, what about these two? What's the difference? (My guess)

He won't have done it by now. - (Probability)
He won't do it by now. - (Fact)

Right?

Anonymous · Answer

TicceHe won't have done it by now. - (Probability)
He won't do it by now. - (Fact)

I am sorry to say that you are only half right. The second one doesn't make sense at all. The aspect is wrong.

You might get away with "He won't be doing it by now", however, or, with a stative verb, "He won't be there by now", but it doesn't work with a non-progressive form of an action verb.

The more usual ways of stating these are with yet:

He won't be doing it yet.
He won't be there yet.

CJ

Ticce · Answer

You are right. I confused it. It should have been - by tomorrow. Please, let me know if these two can be interpreted the way i described provided we switch by now to by tomorrow.

CalifJim · Answer

TicceHe won't have done it by tomorrow. - (Probability)
He won't do it by tomorrow. - (Fact)

(Changed as requested.)

Yes. These make more sense. Still, both say about the same thing, the difference being the same as the difference between the present perfect and the simple past, thus:

1. We won't be able to say tomorrow, "He has done it".
2. We won't be able to say tomorrow, "He did it".

Whether you consider the second one more like a fact is your decision. I would call both of them predictions.

CJ

Ticce · Answer

Oh, I see. I think I need to go into greater detail in order to make my concern more obvious.

What I am trying to find out is whether Future Perfect can convey the probability as in these sentences.

1) You will have heard the news. (You have probably heard the news.)
2) She won't have heard the news. (It is unlikely that she has heard the news.)

In these sentences, as it is said in the grammar book, we have the meaning of probability.

What I am trying to find out is whether it would work the same way with sentences referring to the future. (Or does it only come down to the past.)

3) He won't have done it by tomorrow. (Future probability)

This is what I want to know - does this sentence (3) express probability as we have in (1) and (2)?

On top of that I got the impression, after having been asking a few people about the meaning of these two, that my assumption about the probability may be true. This is what one american guy said.

"He won't have done it by tomorrow - it means that you are not sure that he will do the work by tommorrow or not

He won't do it by tomorrow - means u r sure that he ll not do the work by tommorow"

If I understand him correctly then it, indeed, means that the "He won't have done it by tomorrow" expresses probability. While "He won't do it by tomorrow" express a fact.

But I would like to have it checked with you Jim, as I find you a good expert on this stuff)))

I hope I made it clear.

CalifJim · Answer

TicceWhat I am trying to find out is whether Future Perfect can convey the probability as in these sentences.

1) You will have heard the news. (You have probably heard the news.)
2) She won't have heard the news. (It is unlikely that she has heard the news.)

In these sentences, as it is said in the grammar book, we have the meaning of probability.

Yes. That is quite true. Your grammar book, as you already know, is correct. Those are good examples because they are about something that can be questioned, something that may or may not happen, namely, hearing the news. Maybe you (or she) has already heard the news; maybe you (or she) has not yet heard the news. The knowing or not knowing the news at this moment as the result of having heard it is something that can be assigned a probability.

TicceWhat I am trying to find out is whether it would work the same way with sentences referring to the future. (Or does it only come down to the past.)

3) He won't have done it by tomorrow. (Future probability)

This is what I want to know - does this sentence (3) express probability as we have in (1) and (2)?

I would say it can but it doesn't have to. (3) does not express probability in the same way as (1) and (2) do, though it can. I can make my brain interpret this one either way.

He won't have done it by tomorrow ~ I strongly doubt that tomorrow I'll be able to say, "He has done it".
He won't have done it by tomorrow ~ I am confident that tomorrow I'll be able to say, "He has not done it". <<< This one strikes me as the more usual interpretation for an American to make -- in spite of the other answer you got from someone else.

It depends on the context in which the sentence is uttered -- and the tone of voice, and the expression on the speaker's face, and so on.

TicceIf I understand him correctly then it, indeed, means that the "He won't have done it by tomorrow" expresses probability. While "He won't do it by tomorrow" express a fact.

As for the first part, I think that is one possible interpretation, but not the only one, as I explained above. As for the second part, my only quibble is with the word "fact". I don't think it's possible to have a fact about the future. I would call it a confident prediction rather than a fact, but if you want to call it a fact, that's OK with me. I find it more difficult to see the second example as a case of a statement of a probability. So in summary,

He won't have done it by tomorrow. -- can be a statement of probability, but also usable as a confident prediction.
He won't do it by tomorrow. -- hard to see as a statement of probability, but definitely usable as a confident prediction.

CJ

Will/Shall + perfect infinitive

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