--- On Tue, 11/20/12, David McCann <[log in to unmask]> wrote:

> I think there's a difference between types of indefinites, which isn't
> encoded in English: A [indef specific] nice man helped me out.
> *A bus [indef non-specific] ran him over.
> Polynesian languages would use different articles here.

Actually, I would tend to use "this" as the 'indefinite specific' -- the
man is still indefinite in that we don't know who he is from within the set
of all posible men, but I am still refering to a specific man all the same.

I would use "a" as the 'indefininte non-specific' article -- the man in
question was but one of many nice men and his identity remains both
unknown and unspecified.

The above is quite different from "this" being used as a demonstrative
pronoun -- "THIS nice man" (as opposed to these other nice men over there).