First, an apology to Sandy and Frank - I am suddenly struck by my chutzpah in arguing the meaning of folk with two people who have made it their lives. I have not studied folklore, and am abysmally ignorant of most of the literature, theories and research into folk music. But I love to argue; it's in the Sicilian half...Also, I have been very long away from Mudcat, and am really enjoying jumping back in with my feet firmly planted in my mouth. Nonetheless...(you see, I said I love to argue).
Sandy, I didn't mean to say that rock, reggae, country et al. were all folk. What I meant is that I believe the songs that we today call traditional probably started out as some sort of popular songs in their time, known to more than just one isolated family, else they probably would have died out. While a particular version or variant of a ballad may have been handed down by one family or small group of people, the existence of many versions of a song suggests that it was more widespread in the past (again, similar to genetic divergence and drift). So, too, in the future, long after our demise, people will probably still be singing some of today's "pop" songs, no matter what classification the songs fit into now. If it's a good song, people will hang onto it. (I guess I'm repeating Frank's response to me a bit...)
I still have trouble, though with the ability to define what is a "folk" song or a "traditional" song because of the influences of song collecting and the availability of recordings of songs. My impression of collectors such as Cecil Sharp, Helen Flanders, Lucy Broadwood, et al is that these were educated people who went out into the communities of working-class people, and collected songs from individuals. The way a source(Aunt Sue, say) sang that song on that specific day, in front of a stranger from outside the community, was written down and published in a book. We now call this a "traditional" version of the song, and set it in stone.
But what if Aunt Sue had learned it from her mother, who bought it as a penny broadsheet in town and liked it and sang it around the house a lot? Is it less traditional because it was in print one generation before Aunt Sue? How about 2 generations?
This gets more confusing (to me, at least)once we reach the early years of commercial recordings, when record companies weren't shy about putting out a song by a complete unknown, from Greek rembetica to "hillbilly" music to mandolin orchestras to a black blues singer. People bought them, passed them around, learned songs from them, changed them. Other performers (as opposed to back porch singers) made still other recordings based on earlier ones; this happened a lot in blues music, for example. What's folk here? What's traditional? Who's a folksinger?
It seems a bit easier to narrow definitions when dealing with the cultural background with which I am most familiar, the Anglo-American well of songs, but what happens when cross-cultural mixing starts in, and African cultural elements enter in? In blues, is Robert Johnson's "Crossroads" traditional, composed and/or folk? How about Cajun/Zydeco, where you have a crazy mixed up jambalaya of Anglo, French, African and what-not influences? How do we, as outsiders from that culture, decide what is folk? One more example, from more recent years: Jody Stecher and his partner recorded the Pinder family singing a Bahamian rhyming song they titled "I Bid You Goodnight". I have heard a number of people who have dutifully learned it, word for word, from that recording. But the cultural tradition for rhyming songs was to improvise over a refrain, so that, IMO, a really traditional version of this song should have the singer's own words floating over the repeating chorus. Then it turns out this is a Bahamian version of an English fishing village funeral hymn. Help! which one is a real "folk" song?
Finally (yes, I do go on...)I think the biggest danger to the survival of traditional music is the increasing perception of song and music as something you listen to paid entertainers doing, rather than an enjoyable activity in which everyone can be an active participant. I think taking music classes out of public schools when it's budget-cutting time is one big reason for this - but this can be a topic for a new thread, "Why Johnny Can't Sing..." I rest my soapbox - my feet don't taste so good anymore...