I am still wading through the voluminous amount of posts on this thread. I think I may have more to add. Definitions seem to indicate anomalies. There are exceptions to rules. When you nail down a definition there's always "well what about this?" that may not fit but must be considered.
I am interested in why this discussion is so important. I co-founded a School of Folk Music in Chicago and spent six years teaching there. This discussion was on my mind every day because people were coming into the School to learn something. Even today, there is a dialogue taking place at the School and it's affecting it's direction for the future. I've devoted a good deal of my life tracking down what I considered to be folk songs. At age 65, I'm still tracking 'em. I've had to ask myself many times why I continue to do this.
Here's something I found. People who are interested in folk music want to be a part of it. This informs their arguments about what it is. I think that it's a good thing that people want to be a part of what they think is folk music. But they see it in terms of how it relates to their participation in it and not always for what it is.
I wrote to the president of the Board of Directors at the Old Town School and said this. "It's important to see what it is and not be concerned to much about what it isn't." How do we find out what it is? Well as in any subject worth it's salt, we need more information about it, not just emotional opinions and subjective views. For example, does anyone really know who coined the term "folk music"? Do people who define the music for themselves know about the range of the music and have a working knowledge of all of the performers in the field? One might know of the role of the Kingston Trio but how many people know of say, for example, Vera Hall or Obray Ramsey, Horton Barker or the repitiore of "Blind" Lemon Jefferson? In short, all of the people who have such heated opinions on the subject need to give us information rather than just opinions. This requires a good deal of study in the field. There are damn few people I know who really have studied this field carefully. Bess Lomax Hawes is one I know. Sam Hinton is another one. Pete Seeger knows a good deal about it but is reluctant to get into a discussion of this kind. There are many folklorists, song collectors, musicologists, anthropologists, as well as "revivalist" researchers like myself who have spent a long time on this question. It's not an easy topic to come to hard and fast conclusions about but it's an important one because it brings the light to bear on the subject and what we need to know about it. Why is it important? Because there is a world of wonderful song material that has been handed down from generation to generation and young kids in the public school system are rarely exposed to it compared to the pop music on the boom box. We are paving over the cultural landscape with the cement of limited musical tastes. Has someone noticed what's happening to the NEA these days? What does it say about a country when the NRA is more powerful than the NEA? Can we afford to turn our back on our heritage?
There is a role for the folk song "revivalist" in this picture. And there is an intersection that takes place between popular music and folk music that can't be denied or neatly segregated. This needs to be cleared up by information, not opinion. For example, a student of mine by the name of Roger McGuinn researched folk songs at the Old Town School of Folk Music. He developed a 12 string guitar technique by listening to Pete Seeger, Bob Gibson and had some acquaintance with what Leadbelly did with it. He learned many traditional folk songs and much of this information was carried with him when he did his first recordings with the Byrds. There are other intersections that show the marriage between folk and pop. This is what we need to be talking about. What about a Pete Seeger? Who did he listen to? Why did he decide to become "America's Tuning Fork"? Rather than concentrate on what folk music isn't, let's educate as to what it really is and show us examples.
Stepping off the soapbox, now.