'unless' and 'if ... not' have the same meaning?

anhminh1232002

New Member
(Prefered not to say)
Hello everyone,
I am reading in Longman Dictionary of Contemporary English. They wrote:

WORD CHOICE: unless, if ... not
Use 'unless' to say that something will happen or be true if something else does not happen or is not true : Unless they get protection, they will not testify.
!! Do not use the future tense after 'unless' : I won't go unless you go (NOT unless you will go).
!! Do not say 'unless if' : Don't call him unless it's urgent (NOT unless if it's urgent).
Use 'if ... not' when you know that something did not or will not happen : If he had not tripped, he would have won (=but he didn't win). |: I would go out if it wasn't raining (=but it is raining, so I am not going out).


I am wondering if 'unless' and 'if ... not' have the same meaning.
Can I replace 'if ... not' with 'unless' in the following sentence?

If he had not tripped, he would have won?
Unless he had tripped, he would have won?

Thank you very much.
 
  • e2efour

    Senior Member
    UK English
    Broadly speaking, unless and if....not are interchangeable.
    But the explanation given in the Longman Dictionary does say that if something did not happen, you should use if.....not. I agree, although no doubt someone will come up with an exception to this rule!

    So Unless he had tripped, he would have won is an impossible sentence.

    Another example:
    If Hurricane Sandy had missed New York, the subways would not have been flooded. (=If Sandy had not struck New York.......)
     

    Embonpoint

    Senior Member
    English--American
    I agree with e2four. I think the dictionary explanation is a bit hard to read. Here's another way of trying to make it clear.

    If he had not tripped, he would have won.:tick: Fine. He didn't win.

    Unless he had tripped, he would have won. :cross: Nonsensical. The second part suggests he didn't win. To use unless, the possibility of winning still has to be open.

    Unless he trips, he will win. :tick: The possibility of winning is still open.

    The dictionary says not to use the future tense after unless. That's good advice. I would also add that, while not impossible, it is much less common to follow unless with the past tense. I would stick to unless + present tense while you are learning.
     

    anhminh1232002

    New Member
    (Prefered not to say)
    Could you please tell me what the meaning of the following sentence is?
    Unless they get protection, they will not testify.


    I think it means
    If they do not get protection, they will not testify.


    The two sentences have an relatively equal meaning, right?
    Thank you.
     

    wandle

    Senior Member
    English - British
    The two sentences are different.

    The first expresses the only condition on which they are willing to testify ('will' meaning 'are prepared to').
    It means they have formed this decision in their mind.

    The second states as a fact that they will not testify if they do not get protection ('will' as future tense).
    This is a prediction, a judgement made in the mind of the speaker.

    The two sentences may well both be true at the same time.

    The advice quoted from the Longman Dictionary is a sound guide to English usage.
    It is well expressed in that it puts the points as imperatives: 'do this', or 'do not do that'.
    This is practical advice, telling the learner the best thing to do. It is not laying down an absolute theoretical rule.
     
    Last edited:

    Embonpoint

    Senior Member
    English--American
    Could you please tell me what the meaning of the following sentence is?
    Unless they get protection, they will not testify.


    I think it means
    If they do not get protection, they will not testify.


    The two sentences have an relatively equal meaning, right?
    Thank you.
    Correct.
     
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