"I owe him money" "Me, too." Does the response mean that you also owe someone money? Or does it mean that the man you are speaking to also owes you money?
I would say it depends on context and intonation. And with those two things, no native speaker would be confused. "I owe him money." "Me, too." ("I do, too.") "I owe him money." "Me, too. Remember that fiver I lent you last week?" Honestly I think in the second scenario most people would say, "You owe me, too." The implied meaning of "me, too" is usually "I do, too." "I like music." "Me, too!"
Yes, it can be determined by context and intonation. My point has never been what is commonly said in our language, but what is grammatically correct (I encourage you to see the first post of this thread.) Grammatically, saying "I, too" and "Me, too" mean very different things, regardless of what people can infer from their use. If you say "I, too" you are grammatically saying that you also a person money. If you say "Me, too" you are saying that the person you are talking to also owes you money. I understand that we are not this strict with our usage, but this is linguistically what it means. People also say things like, "Me and her went to the cafeteria," every single day. Doesn't make it correct.
I never said it was incorrect. (At least, I don't believe I did.) I only disagreed with you when you said the distinction is important--I don't think it is. Correctness was never an issue. However, language does change to reflect common usage. I don't think we can dismiss what is said by 99.9% of the populace as simply "incorrect". There is more to it than that. What something "means" does not only come down to its grammar. I do understand that in your first post you were only interested in correctness and nothing else. Just thought I would throw my opinion out there that saying "I, too" seems like a pointless battle. No hard feelings?
Subject personal pronouns: I, he, she, it, they, we, you Object personal pronouns: Me, him, her, it, them, us, you Grammatically correct example: It is I who slew the dragon. OR The person who slew the dragon is I. It would be grammatically incorrect to say: It is me who slew the dragon. OR The person who slew the dragon is me. *This sentence sounds grammatically correct, but it isn't because 'me' is not a subject personal pronoun* Nonetheless, this is colloquially correct because we have trained our ears that way. Just remember the personal pronouns and you should be making grammatically correct sentences. NOTE: Just because a sentence is grammatically correct does not mean it's better. We write stories to entertain people, and the great majority of our audience is the public mass; the public mass uses colloquial speech, not grammatical speech. We are not writing formal and technical pieces when we write stories, so 99.99% of the time, just stick with standard speech colloquialisms. ^Ignore this if you're actually writing formal and technical pieces (science/information/technology/thesis/analysis/research/etc) Also ignore if you want a character to sound posh, upperclass, and educated. In other words: British. LOL. Just kidding (maybe). But yeah, you get what I mean.