Thanks to so many people for your well expressed ideas. I usually avoid these discussions because if I want to discuss any variation of the question "What is the REAL folk music," I have my excellent husband, Bill D, right here to give me the true and final answer.... ;-)

Anyway of all the fine things said in this thread, the one I liked most and am most in sympathy with, is the one from Bronson, that toadfrog quoted.

I almost never go to folk concerts. A major reason (aside from being broke all the time...), is that they usually consist of folk music "presented" by performers, rather than music sung by folks. For me the music that means the most is where the musician is totally connected to the song. Hard to describe.

Well this has nothing to do with singer-songwriters ... except that often they tend to sing music that is personal, but not authentic in the above sense. I think BatGoddess had a good point: most of their music will never become folk songs because no one but the author can sing them.

To offer my answer to the basic question of "why ss/s call themselves folksingers", I suspect that a lot of them started out playing folk-style music, and so still think of themselves as folksingers.