Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
ain’t, amn’t, an’t, a’n’t, aren’t (contrs.)
Am I not is the usually preferred Standard way of negating I am and I’m, although the expression often seems uncomfortably stiff and formal in Conversational use. Long a shibboleth for twentieth-century Americans, the negative contraction ain’t continues to be Substandard when used unconsciously or unintentionally. It is a word, though, and in Vulgar and some Common use, it replaces are not, is not, am not, has not, and have not in statements. Standard English replaces I ain’t with I’m not and the interrogative ain’t I (which is often added to statements, e.g., I’m safe, ain’t I?) with a choice of somewhat clumsy locutions: am I not? aren’t I? or an even more roundabout Isn’t that so? Ain’t probably developed out of the differently pronounced, now rare, and Nonstandard an’t and a’n’t; but it may also have developed from other contractions as well (e.g., amn’t, from am not, or IN-it, a pronunciation of isn’t it?). The firm rejection of ain’t in Standard use is hard to explain, but clearly Americans have come down hardest on it, and they have made the rejection stick in Standard American English. Consciously jocular uses are acceptable, but using ain’t in circumstances that do not suggest deliberate choice may brand you as a speaker of Vulgar English. See HAIN’T.
