How come it doesn't make sense to say "I'm better than you're" when "you're" is short for "you are"?
Read this in another thread, but no one was able to come up with a complete answer. I'm expecting Einherjar to save the day.
I've never been asked this before. Not sure I can save the day, but I can give a few perspectives.
First, I wouldn't say that it "doesn't make sense" to use "you're" at the end of the sentence, "I'm better than you're." If we're reading the sentence, then it does make sense; it just sounds strange. If we're speaking the sentence, on the other hand, it raises potential confusion because "you're" sounds just like "your"; so, if you say to someone "I'm better than you're", they're liable to ask "better than my what?"
That's little more than a practical reply. On a grammatical level, this strikes me as one of those instances of language in which propriety and ordinary use trump rigid grammatical adherence. That said, I do believe there is a rational reason for not using "you're" at the end of a sentence.
In this specific case, "you're" is actually excessive; what the speaker is saying is "I'm better than
you." The "are" is merely an extra verb that clarifies nothing; "I" already
am (presumably, since someone is speaking to me), so I don't really need to specify that I am.
Let's take the following, more complicated example: "I'm better than you're at baseball." The contraction "you're" still seems odd even in this case, when the "are" is needed since something further is being clarified about the direct object "you": "I'm better than you
are at baseball." Professionally speaking, this is a poorly constructed sentence since it relies on the passive; a more appropriate construction would read: "I play baseball better than you do."
That said, I can't think of any strict reason why it's incorrect to use "you're" in this scenario. It's not incorrect to use the passive voice, it simply gets confusing if you use it too much. That would be my "scholarly" explanation, but now I'll give the "better" (i.e. simplest) explanation: it just doesn't sound good.