Some of what Steve says I tend to agree with (sorry, Larry). But a lot of what he says is pure folkum (sorry, Steve).I avoid the whole issue, because I don't consider myself a "folk singer," even though most other people do. I think of myself simply as a singer-guitarist (no one can argue with that; I sing, and I usually accompany myself on the guitar). I sing a number of songs that no one (but the "horsey set") would say are folk songs, and I make no apology for that. It just happens that most of the songs I sing are folk songs. But that doesn't ipso facto make me--or anyone else--a folk singer.
The term has been used in such a all-inclusive manner within recent years that it has lost any real meaning. Which is why there are so many inconclusive arguments as to what a folk singer or a folk song really is.
Don Firth