I have two brothers. The ..........one is Ali.
The tallest !
We're dealing with the SUPERLATIVE, remember?
Is "tallest" really correct here? It's sounds odd to me. In Polish I would never use a superlative adjective describing two entities. It would be understandable and correct in a way but would sound silly. Isn't it so in English?
Yes, in this case it would be the tallest. But if I were talking about two persons or things I would say "the taller". "The tallest" would sound like I wanted to make big deal out of nothing. It would be perfectly comprehensible though but would sound strange, hypercorrect maybe. That's how it works in Polish. Only in the case of exactly two entities. When we have two boys, there's the shorter one and the taller one. I always used it that way in English too.
I hope I'm not irritating
I agree that he's the tallest in the room. I don't have any doubts about that. My doubts are about whether he is the tallest of these two boys or the taller of these two boys. I hope you understand me. I think of it this way: why say he's the tallest when it's enough to say that he's the taller (if he's taller than the other and there are two of them, then of course he's also the tallest). He is the tallest of them in a mathematical sense. But would you say that? I wouldn't neither in Polish nor in English.
PS: To make my point clearer:
Tom is the tallest in the room.
This sentence must be as it is. *"Tom is the taller in the room" doesn't make any sense.
Tom is the taller of these two boys.
This is the sentence that I'm talking about.
No, I would not. This applies only to the case of two (exactly two) entities. When there are more then two it becomes nonsense. "He's the taller of these four." I'm not talking about this. It might be alright in colloquial Polish (I have no idea how it would sound in English). But it's not good because "-er" is used to compare two things, not more.