What do you think about common mistakes?

[jutfrank]

As GoesStation pointed out, when we say "had-a done something" as we very often do in AmE, we don't even know what the -a stands for.

I suspect that this mysterious extra syllable may have appeared as a way to make a smoother transition from one stressed syllable (had) to the next (done). The extra schwa acts to control the rhythm of speech. The fact that this extra schwa tends to appear only before done is perhaps to do with the delayed plosion caused by the double /d/ consonant, an effect that creates a tension that can be avoided by inserting a transitional schwa.

It could be that this extra schwa may have been at some point rationalised by the mind as a word in itself—a weak form of have—to produce the had have mentioned in previous posts. It could be that from this had have came the contracted form 'd have and from there the 'd came to be realised as a short form of would, finally producing the would have (done) that we hear today.

All this is just my own very amateur theorising, by the way. I have absolutely no academic authority on any of this. I'm not even especially convinced by my own theory. I do find it very interesting, though.

 

[probus]

It's not only before done.

Had-a said...
Had-a followed,,,
Had-a stumbled ...
Has-a anything really.

I think it is the exact American equivalent of had've in BrE.