I'm not hung up on definitions of Folk...., I can't really say, though where Irish Trad and 'World Music' (now there's something worth defining....) meet..., or if indeed they separate at all..... ;-)

I wouldn't book ACDC for a Folk Club, but I would, John Martyn, for instance.

I generally stay away from 'defining' Folk Music, but I know this debate intimately, and if we are going to start 'defining', then 'definitions', as Richard points out, have to be made, and the first analogy that springs to mind is that it can be as difficult as describing the colour 'Blue' to a blind person.
... on both sides of the argument.

The 'Folk Police', though ... a different body of people altogether have not been effective (in Ireland, anyway) since the Bothy Band split up.
Folk music in whichever pigeon hole one cares to put it in, will continue to evolve, and in 2054 we may have a totally new concept of the 'genre'

A lot of our World, however, will be Museum exhibits at that stage, and hopefully I'll have learned to play the Harp by that time... ;-)

I join Al, too in thanking Bruce for his inclusion of me in his '... to name but a few..' list.
I'm speechless.
... for once in my life....

Thanks a million Bruce
... now there's a pro...

B.