# Unless vs if not



## Ivan_I

I think the 2 are correct. Do you agree?
1 John has arrived by now *if *he didn't get stuck in a traffic jam.
2 John has arrived by now *unless *he got stuck in a traffic jam.

_Let's change them a bit_


3 John would be there by now *if *he hadn't got stuck in a traffic jam. (I think it means that the speaker *knows *that John has got stuck in a traffic jam.) 
4 John would be there by now *unless *he had got stuck in a traffic jam. ( I don't like it)
5 John would be there by now *unless *he got stuck in a traffic jam. (Maybe correct) 

What do you think of 4 and 5? Do you agree with my reaction?


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## e2efour

Nos. 1 and 2 are wrong because he hasn't arrived.
You should say _John will/must have arrived by now._


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## Ivan_I

How do you know that he hasn't arrived?


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## e2efour

We don't know for certain that he has arrived, which is why you should not say it.
The sentence should contain some element of doubt.


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## Ivan_I

I am confused. What should I not say? Should I not say that *he has arrived*? But why not? I am sure that he has arrived *unless*... Isn't *unless *used exactly for this kind of purpose?

a John will arrive (come) here soon unless he gets stuck in a traffic jam. (Isn't it a perfect sentence?)
b John arrives (comes) here _every week_ unless he gets stuck in a traffic jam. (Isn't it a perfect sentence?)
So, what's wrong with:
c John has arrived (come) here  *unless *he got stuck in a traffic jam.

I agree that  _John will/must have arrived by now._ fits very well. But it's only a matter of the degree of the confidence. By saying "John has arrived..." I simply display a high level of confidence. (I believe that he has arrived, though, he well may have not.) Is it grammatically wrong?


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## intrigue

I agree with e2efour.
If you say 'John has arrived' you are not leaving any room at all for doubt. It's more than a high level of confidence, you are stating it as a fact. He has arrived. 
So it is not appropriate to then qualify that fact with an explanation that suggests he may not have arrived.
You could say "I expect John has arrived, unless he got stuck in a traffic jam."  That would be perfectly correct.


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## e2efour

Thank you, intrigue, for your explanation.
I had got as far as writing the following in an attempt to explain the difference, but it is not sufficient in itself:

_John has arrived_ is a statement of fact.
_John will have arrived by now_ is a prediction.

Note that we sometimes say things like _He has now retired, if I am not/unless I am mistaken._


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## Ivan_I

Well, it makes sense. But *John arrives (comes) here every week unless he gets stuck in a traffic jam. *is also a fact. But I think the sentence is correct? What's the reason?


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## MattiasNYC

e2efour said:


> Note that we sometimes say things like _He has now retired, if I am not/unless I am mistaken._



Do you think this is an exception on a case-by-case basis?


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## Edinburgher

Ivan_I said:


> But *John arrives (comes) here every week unless he gets stuck in a traffic jam. *is also a fact.


It's a different kind of fact (well, it's not really a fact at all): it's a generalization that allows for exceptions.  When you say he *has* arrived (now), it's specific. You cannot attach a condition. You would have to weaken the statement into a supposition, such as "he *will have* arrived".


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## e2efour

MattiasNYC said:


> Do you think this is an exception on a case-by-case basis?


I'm not sure what you mean by a _case-by-case basis_, but _if I am not mistaken _is like _as far as I know. _
There is no actual condition involved.


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## Ivan_I

Do you agree with my reaction to 4 and 5?



Ivan_I said:


> 4 John would be there by now *unless *he had got stuck in a traffic jam. ( I don't like it)
> 5 John would be there by now *unless *he got stuck in a traffic jam. (Maybe correct)


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## Edinburgher

Ivan_I said:


> Do you agree with my reaction to 4 and 5?


Yes, "had" is a problem in (4).  In (5), I'd change _would_ to _should_.


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## MattiasNYC

e2efour said:


> I'm not sure what you mean by a _case-by-case basis_, but _if I am not mistaken _is like _as far as I know. _
> There is no actual condition involved.



What I meant was that the structure that was discussed in the first post looks like this to me:

_- *something has happened* *unless* *something else is true*_

Therefore the structure is the same for both of the sentences below:

_*John has arrived by now* *unless **he got stuck in a traffic jam*
*He has now retired**, **unless** I am mistaken. *_

So it seemed to me that you were saying that the second sentence above was something we sometimes say and is "ok", whereas the first is not ok, and therefore I was wondering if we sometimes just ignore the logic behind the first not being correct - i.e. on a case-by-case basis.


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## e2efour

I mentioned the sentence with _unless I am mistaken_ as an example that, at first glance, appears to be similar to _he has arrived unless ..._
But it is worlds apart since there is no condition.

It may be possible, with some difficulty, to think up a context with another verb than _arrived_ that works.
I certainly can't at the moment.
The original sentence, when I think about it, does not appear to be a condition, and it does not follow any pattern of conditional sentences that I have ever heard.


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## MattiasNYC

I'm still a bit confused though.

On the one hand the last part of your post makes it seem like you're talking about what I suppose we could call "correct" usage of language, meaning as you say patterns of conditional sentences that are essentially correct English.

But on the other hand it looks as if the discussion is about logic, not language, in which case I do see a condition in both sentences. If one thing is true (the latter) the other one (the former) isn't. 

So since you said that on second thought the original doesn't appear to you to be a condition either but your example is being used I would still like to know why the original wouldn't be proper or used whereas your example is. It would seem inconsistent to me which explains why I was asking if it was just a type of incorrect wording that is used on a case-by-case basis (rather than a rule).


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## e2efour

Can you give me an example of _somethning has happened unless something else is not true_?
Once you have said that something has happened (past reference), you cannot change it by giving a condition.
We might, of course, have the following dialogue where the _if_ clause casts doubt on the initial factual statement:
A_ Where is he living now?_
B _He has bought a house in Germany if his sister is to believed._

I don't regard this as a condition in the normal sense of the word. If you can change the _if_ clause so that the main clause is conditional on it, you get a sentence which cannot be said. Whether we say it's illogical or ungrammatical is something that one can argue about. If the main clause contains a past reference (i.e. the perfect tense), it cannot depend on the _if_ clause.  A sentence like _He has died unless the doctor made a mistake_ makes no sense at all to me.

In the same way, _if I am not mistaken_ is just a formula throwing doubt on what has just been said.


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## MattiasNYC

e2efour said:


> Can you give me an example of _somethning has happened unless something else is not true_?
> Once you have said that something has happened (past reference), you cannot change it by giving a condition.
> We might, of course, have the following dialogue where the _if_ clause casts doubt on the initial factual statement:
> A_ Where is he living now?_
> B _He has bought a house in Germany if his sister is to believed._




But isn't it all about doubts and caveats though? I don't see how "if his sister is to be believed" is any different from "if traffic was smooth" (or whatever). Both examples again state that something has happened and then the caveat follows. It casts doubt on the first clause.

I guess I just don't see your reasoning for _when _it is acceptable to use that structure and when it isn't.



e2efour said:


> If you can change the _if_ clause so that the main clause is conditional on it, you get a sentence which cannot be said. Whether we say it's illogical or ungrammatical is something that one can argue about. If the main clause contains a past reference (i.e. the perfect tense), it cannot depend on the _if_ clause.  A sentence like _He has died unless the doctor made a mistake_ makes no sense at all to me.



Well, if I read that sentence the problem isn't the structure but the fact that patients typically die if a doctor _does _make a mistake. If you instead wrote "He has survived unless the doctor made a mistake" then regardless of what you think about the style of that writing or its "correctness" it's entirely understandable to me. We're assuming that the person has survived because the only reason he wouldn't have survived is if the doctor made a mistake. That's what that sentence looks like to me. And it's the same thing saying that John has arrived; it's something we expect to have happened but there's a caveat which is traffic conditions. Barring that he has arrived.

I'm struggling to understand what governs _when _a construction like the one we're talking about is fine. In your view.


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## e2efour

It is possible to say _John is there by now, unless he has been caught in a traffic jam. _I accept that some people might speak like this, although I would prefer to say _John must be there by now ..._

But I cannot imagine anyone saying_ John has arrived, unless he has been caught in a traffic jam. _The rule (if there is one) is that a past tense cannot be stated as a fact and then possibly contradicted by the next clause. It might be acceptable to say it in response to the question _Has John arrived? _But even then I would insist on something like _I assume/expect he has arrived_ or _He will have arrived. _That is my grammatical explanation.

Note that the verb _has arrived_ is an event that is over and done with; it has happened in the past and cannot be undone. It is like saying _He has had chicken for dinner_, _but he has changed his mind. _Besides being ungrammatical, this also sounds completely illogical or impossible. One could certainly say _He will have had chicken for dinner, unless he changed his mind._ The change from a factual statement to a prediction makes the sentence acceptable.

In the sentence _He has survived unless the doctor made a mistake_, we do not have a completed action which cannot be reversed. In other words, his survival continues up to the present.


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## lentulax

'John has arrived by now.'  In what context would we make this statement?


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## Edinburgher

lentulax said:


> 'John has arrived by now.' In what context would we make this statement?


In none at all, I reckon.  It just doesn't work, unless you take "by" out.


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## Andygc

lentulax said:


> 'John has arrived by now.'  In what context would we make this statement?


I saw John leave at 3 pm. It's a 30-minute walk to his destination. It's 5 pm. I look at my watch. "John has arrived by now." (I consider there to be no possibility that he could have been delayed.)


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## Edinburgher

Then I'd say he "must have arrive by now".

Edit:  Oops, typo.  I meant *arrived*.


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## Andygc

I hope not. I hope you would say "must have arrived".

I was providing a context where it could be said, not where it would necessarily be said. And why "must"? "He will have arrived by now" is yet another possibility. But none of that is really relevant to this being wrong:


Ivan_I said:


> John has arrived by now *if *he didn't get stuck in a traffic jam.


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## Edinburgher

Andygc said:


> I hope you would say "must have arrived".


Of course.  Fingertrouble, sorry.  And of course "will" is another possibility.


> But none of that is really relevant to this being wrong:


I'm not sure it is entirely irrelevant, because "John *must/will have* arrived by now if he didn't get stuck..." seems fine.
Basically there are two reasons why "has ... if" is wrong. Either of them suffices to condemn it.


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## Ivan_I

e2efour said:


> The original sentence, when I think about it, does not appear to be a condition, and it does not follow any pattern of conditional sentences that I have ever heard.


I am having difficulty categorizing the sentence in terms of the conventional system of conditionals. It's none of 0,1,2,3 or the mixed one, however, I think it is conditional. Have a look at a similar one.

If he left for London yesterday he will arrive tomorrow.

It doesn't fall in any conventional conditional type BUT ... IT IS conditional, isn't it?


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## sound shift

Ivan_I said:


> If he left for London yesterday he will arrive tomorrow.
> 
> It doesn't fall in any conventional conditional type BUT ... IT IS conditional, isn't it?


I don't think it can be called a conditional, because the meaning is: "If it's the case that he left for London yesterday ..." (the speaker doesn't know whether it is the case) or "Given that he left for London yesterday ..." (it is a fact that he left for London yesterday). I don't see a condition to be fulfilled in either case.


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## Ivan_I

sound shift said:


> I don't see a condition to be fulfilled in either case.


I can see the condition. "If it's the case that he left for London yesterday ..." sounds like conditional to me. If it's not, what is it?


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## Edinburgher

Ivan_I said:


> "If it's the case that he left for London yesterday ..." sounds like conditional to me. If it's not, what is it?


It's just an ordinary type 1.  Condition in simple present ("if it is the case that he left yesterday"), main clause in simple future.
The original version "if he left yesterday" is just the same, except that you have to imagine "is the case that".  If he left yesterday, the fact that he did so is still true now.  The usual recipe for type 1, that the condition should be simple present, is just an oversimplification.  The important thing is that the outcome mentioned in the main clause is possible and probable if the condition is met.


sound shift said:


> I don't see a condition to be fulfilled in either case.


I agree that it's not a condition if we take the "given that" meaning, but if the speaker doesn't know, then it is, and speaker is saying "if it's true, then he will arrive, but if it isn't, then I'm offering no comment regarding his arrival."


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## MattiasNYC

e2efour said:


> It is possible to say _John is there by now, unless he has been caught in a traffic jam. _I accept that some people might speak like this, although I would prefer to say _John must be there by now ..._
> 
> But I cannot imagine anyone saying_ John has arrived, unless he has been caught in a traffic jam. _The rule (if there is one) is that a past tense cannot be stated as a fact and then possibly contradicted by the next clause. It might be acceptable to say it in response to the question _Has John arrived? _But even then I would insist on something like _I assume/expect he has arrived_ or _He will have arrived. _That is my grammatical explanation.



Thanks. Now I understand your reasoning better.



e2efour said:


> Note that the verb _has arrived_ is an event that is over and done with; it has happened in the past and cannot be undone. It is like saying _He has had chicken for dinner_, _but he has changed his mind. _Besides being ungrammatical, this also sounds completely illogical or impossible. One could certainly say _He will have had chicken for dinner, unless he changed his mind._ The change from a factual statement to a prediction makes the sentence acceptable.
> 
> In the sentence _He has survived unless the doctor made a mistake_, we do not have a completed action which cannot be reversed. In other words, his survival continues up to the present.



I think part of the reason I didn't / don't understand your reasoning is that you seem to be changing your examples so that the structure and meaning is different. "He has had" followed by "but" isn't an 'incorrect condition', because it isn't a condition at all, it's just a contradiction. So it doesn't really work as an example of why a certain way of wording a condition doesn't work.

As for "happened in the past and cannot be undone" and "a completed action which cannot be reversed" I still don't see how it makes a difference from a logical standpoint. If this is how it is in "proper" English - grammatically - then fine, of course I won't argue that, but it doesn't seem relevant logically. Having survived is something that is still the case of course _but it is implied_ that we are talking about an event in the past nonetheless since we brought up the doctor having (not) made a mistake. So really what we're hypothetically talking about is an event in the past in which the person was treated by the doctor and it either went poorly (death) or it went well in which case the person survived. That's to me "completed action".

I do think this all boils down to a larger question perhaps (but still related to the topic). See next post..


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## MattiasNYC

Edinburgher said:


> I agree that it's not a condition if we take the "given that" meaning, but if the speaker doesn't know, then it is, and speaker is saying "if it's true, then he will arrive, but if it isn't, then I'm offering no comment regarding his arrival."



It seems to me that when we look at what a speaker says we interpret the totality of it and it then influences the parts of the whole, for lack of better wording. Therefore certain things are implied, at least to some people. Take "intrigue's" comment for example:

_" You could say "*I expect *John has arrived, unless he got stuck in a traffic jam." That would be perfectly correct. "_

To me "I expect" is actually pretty clearly implied because of that condition in the second part of the sentence. It seems obvious to me that the speaker isn't saying two things at the same time: That John has arrived (no caveat) and that he might not have arrived. Why? Because the word "unless" makes it clear to me that there is a caveat and that caveat implies that the speaker isn't 100% sure. Therefore the "John *has* arrived" isn't nearly as strong as if it stood by itself.

Another example:

" _John is there by now, unless he has been caught in a traffic jam._ "

To me it is again implied that the speaker has an expectation that hinges upon a condition. I don't see the difference between "is there" or "has arrived" logically because in order for the meaning to be true in either case John would have had to have travelled. So in both cases it is true that John is supposed to have travelled to a location, and if traffic was fine he "has arrived"... if traffic was fine he "is there"... Same meaning. He can't "be there" without "having arrived", or vice versa.

So I guess my question is to what degree we allow for what is clearly (?) implied to influence whether or not a sentence is correctly written...

?


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## Edinburgher

MattiasNYC said:


> So I guess my question is to what degree we allow for what is clearly (?) implied to influence whether or not a sentence is correctly written...


I concur with e2e4 that if there is a condition that can be false (even if the possibility is remote), then the main clause should not be expressed in a grammatically unconditional way, even when the "contradiction" does not come as a surprise after the fact has been stated, but is instead mentioned first.  By this I mean that
" _Unless he has been caught in a traffic jam, John is there by now._ "
is just as wrong as
 " _John is there by now, unless he has been caught in a traffic jam._ "
Both of them need something less overtly unconditional than "is there".  It needs to be to some extent non-committal: _he will be there, he should be there, he ought to be there, he is probably there._

As a separate issue, he either is there or he isn't.  If he is, he's there now, not by now.


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## MattiasNYC

Edinburgher said:


> *I concur with e2e4 *that if there is a condition that can be false (even if the possibility is remote), then the main clause should not be expressed in a grammatically unconditional way, even when the "contradiction" does not come as a surprise after the fact has been stated, but is instead mentioned first.  By this I mean that
> " _Unless he has been caught in a traffic jam, John is there by now._ "
> is just as wrong as
> " _John is there by now, unless he has been caught in a traffic jam._ "
> *Both of them need something less overtly unconditional than "is there".  It needs to be to some extent non-committal: *_he will be there, he should be there, he ought to be there, he is probably there._




But it was e2e4 who wrote: *"It is possible to say *_*John is there by now*, *unless *he has been caught in a traffic jam. _I accept that some people might speak like this, although I would prefer to say _John must be there by now ..._ "

And this is why it looks a bit confusing. I don't see a consensus, neither do I feel I hear one when people speak.



Edinburgher said:


> As a separate issue, he either is there or he isn't.  If he is, he's there now, not by now.



See above.


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## Edinburgher

MattiasNYC said:


> But it was e2e4 who wrote: *"It is possible to say *_*John is there by now*, *unless *he has been caught in a traffic jam. _I accept that some people might speak like this, although I would prefer to say _John must be there by now ..._ "
> 
> And this is why it looks a bit confusing.


I should have focused on the "has arrived" example instead, which e2e4 clearly disapproves of.  I don't understand why he thinks the "is there" case is possible, because he clearly doesn't approve of it.  They both seem to me to be equally unequivocal statements of fact to which it doesn't make sense to attach a condition.


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## e2efour

There is sometimes a fine line between saying that something is possible and rejecting it completely. You can be accused of being either prescriptive or not prescriptive enough_, _if someone disagrees with you. I am certainly prescriptive in certain circumstances (e.g. I can't accept the use of _forgoed_ instead of _forwent_, although if enough people use the former, it may be necessary to change one's mind).

My focus was on the use of a past tense (_has arrived_), which I deny that anyone could logically (and probably grammatically) say. Is there anyone who would be prepared to accept it? In this case I am wholly prescriptive.

The phrase _is there_ refers to the present and it might be possible to provide a context for contradicting it. I deny the use of _has arrived_ instead of _he will have arrived_ because I can see no possibility of it working. In addition, I find it difficult to come up with a rule against it (if, that is, anyone would ever say it).


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## MattiasNYC

Edinburgher said:


> both seem to me to be equally unequivocal statements of fact to which it doesn't make sense to attach a condition.



Actually, if I search for "unless I'm mistaken" I find several instances where if we simply delete the condition or 'caveat' and let the other part of the sentence stand alone it appears "unequivocal" as a statement. I'm guessing however that if you were the editor-in-chief and I quoted someone like Ivan and only took the first part of his sentence you would have a problem with it, because the second part _is _relevant and _does_ change the meaning of the entire statement. So I don't really see how as a principle that really works. For reference:

mistaken adjective - Definition, pictures, pronunciation and usage notes | Oxford Advanced Learner's Dictionary at OxfordLearnersDictionaries.com
and
unless conjunction - Definition, pictures, pronunciation and usage notes | Oxford Advanced Learner's Dictionary at OxfordLearnersDictionaries.com


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## Roxxxannne

I can easily imagine saying "John has arrived by now, unless he was delayed by the construction they're doing on the highway."

I know John is driving from A to B, a trip that normally takes three hours.  I know he left A a little more than three hours ago.  So I imagine he's arrived and I say "John has arrived by now."  Perhaps I say this because I can text him now and he will reply right away without committing the dangerous act of texting while driving.   Then I immediately remember, as I visualize the route in my mind, that there is a lot of construction taking place on the highway between A and B, so I qualify my previous statement: "unless he was delayed by the construction ... ."

In other words, I'm making a unequivocal statement and then contradicting it right away.  I can't erase what I just said (John has arrived by now) so I just soldier on in the conversation with two halves of a sentence that don't match, rather than a single, grammatically correct sentence.


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## Edinburgher

MattiasNYC said:


> I'm guessing however that if you were the editor-in-chief and I quoted someone like Ivan and only took the first part of his sentence you would have a problem with it, because the second part _is _relevant and _does_ change the meaning of the entire statement.


If there is no second part, I couldn't possibly know that it's relevant.  But yes, I would have a problem with standalone "He is there by now", but that's because of "by", not because of a "missing" second half.  I couldn't bring myself to say "John has arrived by now" either.  It would need to use "must have".  I think my objection to "by" is unrelated to my dislike of combining the first half with a condition, because I'd also object to "He is there now, unless..."

But you're right, it's difficult to extract a general principle, because I have no objection at all to "That's Paul's wife over there, unless I'm very much mistaken."


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## lentulax

Edinburgher said:


> it's difficult to extract a general principle, because I have no objection at all to "That's Paul's wife over there, unless I'm very much mistaken


Well, this isn't a forum for philosophers, logicians or linguists, who have found the conditional a very tricky matter, so I won't attempt definitions; the 4 conditional types are, after all, a convenient formulation to assist learners with English tense usage, and don't pretend to be an exhaustive logical analysis. As e2efour has (repeatedly) said, 'if I'm not mistaken' and similar expressions obviously are a different case from other 'if' clauses; they're a sort of petitio principii, since effectively they mean 'X is true unless it's not true' : 'John is here somewhere , if I'm not mistaken' = John is here if I'm not wrong in thinking he's here'; the function of the 'if' clause, as e2 has said, is simply to acknowledge the possibility of error. (In other conditional sentences, the relationship of the 'if' clause to the main clause may be a cause-effect link between two events, and so on.)


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## MattiasNYC

Edinburgher said:


> If there is no second part, I couldn't possibly know that it's relevant.



I gave you an example in which you are aware that there is a second part. Obviously if you change my example it no longer works. But if you're proofreading what I've written _and _checking what the source actually said or wrote then you would see that there were two parts to the statement, and you'd have a problem with my quote because the second part actually does change the meaning of the whole - would you not agree?



Edinburgher said:


> But you're right, it's difficult to extract a general principle, because I have no objection at all to "That's Paul's wife over there, unless I'm very much mistaken."



Right. It _appears to me_ to be the exact same problem. It's a first part that is unequivocal that is then given a caveat in the second part. So this brings me back to if whether or not this is 'acceptable' to people is on a case-by-case basis, and it appears to me that that's the case.


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## MattiasNYC

lentulax said:


> As e2efour has (repeatedly) said, 'if I'm not mistaken' and similar expressions obviously are a different case from other 'if' clauses; they're a sort of petitio principii, since effectively they mean 'X is true unless it's not true' : 'John is here somewhere , if I'm not mistaken' = John is here if I'm not wrong in thinking he's here'; the function of the 'if' clause, as e2 has said, is simply to acknowledge the possibility of error. (In other conditional sentences, the relationship of the 'if' clause to the main clause may be a cause-effect link between two events, and so on.)



It seems to me that if the job of the "if" / "unless" function is "simply to acknowledge the possibility of error" then it isn't really a petitio principii since it's not really an argument.


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