I remember discussing this issue in a linguistics class many years ago.
(Can it really be 30 years since I took that class? Heavens to Betsy!)

Anyway, as best I can remember, the confusion is caused by having two
methods of showing possession--the modern way with the possessive morpheme
and the old way with the genitive expressed as a preposition phrase. In
some cases, we use both of them, although only one is required. That would
be why "a friend of Bill Clinton" and "a friend of Bill Clinton's" would
co-exist. The second one uses both methods of showing possession.

I would guess, then, that "a friend of his" became the only alternative,
not co-existing with "a friend of him," by some sort of process of idiom
formation.

Of course, it's all a guess. That WAS 30 years ago when I took that course.

Bill McCleary

>To give everybody a rest from Henry James:
>
>An ESL student in my class wrote, "Now I am a friend of him."  Is there a
>good reason I can give him for why it should be "of HIS"?
>
>It gets funny with proper names, too.  If we knew each other well, I might
>describe myself as a friend of Bill Clinton's.  But, at least for the
>first four or five days of his term, I would have described myself as a
>supporter of Bill Clinton.  Go figure.  Please.


William J. McCleary
3247 Bronson Hill Road
Livonia, NY 14487
716-346-6859