Hi Andrew,

Good question; it’s an interesting area of linguistics where the language has developed to only use “aren’t I”, most likely because it’s simply easier to pronounce. This is really established now and would be considered correct, while “amn’t I” is never used and would be considered incorrect (though without a contraction we still say “Am I not?”). Meanwhile, while “you are not / he is not” can become “you aren’t / he isn’t” or “you’re not / he’s not”, “I am not” most commonly/correctly only becomes “I’m not”.

What’s interesting, though is that we do have a contraction that connects more logically with “I”, which quite possibly came from “amn’t”: “ain’t”. “Ain’t” is very much still in use, and can actually be used with any pronoun, so it probably started out as the most specific contraction, for just “I”, but has since become the most flexible. However, somewhere along the road, “ain’t” was frowned upon and is not now considered “good English”, but rather vulgar. One of those strange quirks of English where a negative opinion has developed around a word that, on its own (“Amn’t I” -> “Ain’t I?”), actually makes more sense than the accepted form! It’s probably a case worthy of an article all of its own.

Phil