The expression aren’t I is often used in place of am I not, particularly in conversational speech.
Example 1 (incorrect usage): I’m going with you on vacation, aren’t I?
Although the use of this phrase is widespread, it is atrocious English that could be considered equivalent to you is, a phrase which most educated people abhor (although for some reason, these same people have no qualms about saying aren’t I). The correct form of the sentence in Example 1 is as follows:
Example 2 (correct usage): I’m going with you on vacation, am I not?
If you read this sentence aloud, it probably sounds awkward and formal, perhaps even a bit hoity-toity. However, it is correct English. If the phrase aren’t I is converted from a question to a statement, I aren’t, it becomes obvious that it is indeed grammatically incorrect.

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Comment by Eldie — January 19, 2010 @ 5:33 pm
If you just disassemble the contraction “aren’t,” you will see it is actually “are not”. So, “are not I” is definitely NOT correct.
Comment by Eric — January 20, 2010 @ 5:48 pm
Ok, I understand that ‘I are’ is not the correct conjugation of the present tense of ‘to be’. However, in the example sentence, isn’t the verb being used in a ’subjunctive’ mood in which the specific event may or may not occur? For example, in the sentence “If I were to go with you on vacation…”, the conjugation of ‘to be’ as ‘I were’ is not the formal conjugation for the first person singular. But because the event is conditional and abstract rather than concrete, the alternative conjugation is used. So why not here? Simply saying that ‘I are’ isn’t correct does not solve the problem, guys.
Comment by Andy — February 1, 2010 @ 5:44 am
Andy, you may be correct. Who am I to argue with a brain? But you have added fuel to the fire. Would you re-state your comment, with a great deal of simplification? You know, endeavor to help us simpletons.
Comment by Bill — February 13, 2010 @ 1:33 am
I didn’t mean to make my comment sound too complex, and I’ll rephrase in a simpler way.
In English, when people are talking about events that may or may not happen, they often use the ’subjunctive mood’, something that is used a lot in other languages but is all but lost from english. For example, in the phrase I listed “If I were to go…”, we use an alternative to “I was” because the event in question may or may not occur. This is pretty much the last vestige of the subjunctive in english, yet “I were” is indeed correct in this case. So, my question then, is why can’t we say “aren’t I” if we are discussing events (say, going on vacation) that are uncertain?
Comment by Andy — February 16, 2010 @ 3:44 am
Andy, I completely agree. I’ve been trying to figure out why Standard American and British English would use “aren’t I” instead of “amn’t I”, as they do in Ireland, or “ain’t I”, as much of the English-speaking world does. i.e. what is the grammatical rational?
Your explanation with the subjunctive makes sense — as it is in the interrogative, that could be interpreted as a subjunctive. For instance in French there are certain verbs that in the affirmative you would use the indicative, but if it’s in the negative or the interrogative you use a subjunctive.
Comment by Jackson — February 21, 2010 @ 5:30 am
rationale*
Comment by Jackson — February 21, 2010 @ 5:30 am
Thanks for the opinion, Jackson. I appreciate it. The analogy with french is an interesting one, since french is a language where the subjunctive is alive and well.
Comment by Andy — February 22, 2010 @ 4:23 am