# Difference between בלתי אפשרי and אי אפשר?



## facarraro

Hey guys!

I've seen that both of those can be used to say "impossible". What's the difference?

Thanks!


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## slus

בלתי אפשרי is impossible
אי אפשר is can't
You can say זה בלתי אפשרית
But אי אפשר לעשות את זה


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## تلميذ

Are אי and בלתי related to אין and בלי (resp.)?


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## JoMe

تلميذ said:


> Are אי and בלתי related to אין and בלי (resp.)?


Apparently yes, but not sure how robust the evidence is. For example, the trio בל-בלי-בלתי is explained by the Hebrew Academy as probably related to root בלה = decay, which seems to me as a mere guess.

All are biblical words, most or all of them are shared by other languages like Phoenician, Ugaritic.


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## تلميذ

JoMe said:


> Apparently yes, but not sure how robust the evidence is. For example, the trio בל-בלי-בלתי is explained by the Hebrew Academy as probably related to root בלה = decay, which seems to me as a mere guess.
> 
> All are biblical words, most or all of them are shared by other languages like Phoenician, Ugaritic.


Thanks for the explanation and the useful links.


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## GeriReshef

I think that from a practical point of view, they are almost perfectly interchangeable.
It is very difficult to find an exception (where you can use only one and not the other).


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## amikama

משימה בלתי אפשרית
An example in which בלתי אפשרי can't be replaced with אי אפשר.

I think it's because בלתי אפשרי is either adjective or adverb, while אי אפשר is adverb only.


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## Samuel B. Tovim

The insight regarding the distinction between adjectives and adverbs is, it seems to me, pretty much in the right direction. "אפשרי" is the adjective, "בלתי" is a negation word that applies to adjectives. That "אפשרי" is an adjective may be proven by noting that we can decline it, אפשרי-אפשרית-אפשריים-אפשריות. That "בלתי" is a standalone negation word may be seen by considering constructions such as "בלתי רגיל" (unusual) and "בלתי הפיך" (irreversible, irrevocable). I take it that it's intuitively obvious that בלתי צדק | בלתי סדר | בלתי היטב are wrong, so it would seem that בלתי cannot be used with nouns or adverbs, only with some adjectives. This, presumably, is why "בלתי אפשר" sound so wrong. 

The word "אפשר" in "אי אפשר" is an adverb. It means "possibly, it is possible that...", i.e: אפשר שאני טועה - it is possible that I am wrong, I am possibly wrong . The word "אי" is a negation word. By inserting it before "אפשר", we get "it is not possible that...". The word "אי" may, of course, also be used to form other constructions, such as "אי-צדק" (injustice), "אי סדר" (disorder), and "אי-הבנה" (a misunderstanding). 

Assuming the validity of the foregoing, it would be grammatically incorrect to say "אפשרי ש" or "בלתי אפשרי ש", because such constructions require an adverb (אפשר), not an adjective. But even if true, spoken language seldom adheres to the strictures of grammar, so this is really more an intellectual exercise than anything else, and you may well find all sorts of constructions in the real world.


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## Drink

Samuel B. Tovim said:


> Assuming the validity of the foregoing, it would be grammatically incorrect to say "אפשרי ש" or "בלתי אפשרי ש", because such constructions require an adverb (אפשר), not an adjective. But even if true, spoken language seldom adheres to the strictures of grammar, so this is really more an intellectual exercise than anything else, and you may well find all sorts of constructions in the real world.



Actually, I think pretty much any adjective can serve as an adverb, but not the other way around. So this would actually be grammatically correct.


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## JoMe

> it would be grammatically incorrect to say "אפשרי ש" or "בלתי אפשרי ש


Morfix dictionary permits it, I'm not sure if it's reliable in such matters.
מילון מורפיקס | מן הנמנע באנגלית | פירוש מן הנמנע בעברית



> I think pretty much any adjective can serve as an adverb


We say אני איטי but not אני הולך איטי, that would be אני הולך לאט or אני הולך באיטיות.


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## Drink

JoMe said:


> We say אני איטי but not אני הולך איטי, that would be אני הולך לאט or אני הולך באיטיות.



Maybe it's only certain kinds of adjectives. But regardless, it's certainly common for adjectives to be uses as adverbs.


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