Consider, if you will, the following sentence –
I’m the epitome of tolerance, aren’t I?
Ignoring the veracity or otherwise of this remark, is there anything wrong with it, grammatically speaking?
If you search the web, you will find several sites which condemn it out of hand as “appallingly bad grammar”. They expand the interrogative tag as “are not I”, pedantically point out that the verb to be is not correctly conjugated – the verb form does not agree with the subject – and swiftly move on to other prescriptive matters.
But they are wrong! In fact it’s perfectly good English – as well as being exactly what most English speakers would say naturally. Speakers of Scottish and Irish English follow other patterns, so no complaints from the Jockinese Charioteers, please.
The trouble is, the prescriptive grammar police haven’t done their homework. They assume (never assume) that the aren’t in aren’t I? is the same word as the aren’t in aren’t you? But it isn’t!
The formally correct tag is, of course, “am I not?” – I’m sure nobody will disagree with that. Well, back in the olden days one said am not I? and in colloquial speech, this became contracted to amn’t I? – which is what our Jockinese friends still say. Because English speakers have a problem pronouncing the mn consonant pair, the m was elided to yield an’t I? – first in speech and then in writing.
Now we get to the really interesting bit. The a in an’t I? can be either short or long. This is to some extent a dialectical choice, but the normal English speech preference is to make it long. Compare this with can and can’t. The a in can is short, but when we negate the word with n’t the vowel naturally goes long. Can, but cahn’t.
Hence an’t I? was actually pronounced ahn’t I?. To non-rhotic speakers (which most of us are), this sounds identical to aren’t I? So about 150 years ago, it began to be printed that way, instead of an’t I?.
So when we say aren’t I?, we’re actually saying ahn’t I?, from ahmn’t I?, from am not I? – and it’s good, correct grammar.
Now don’t get me started on ain’t. 😀