The suggestion that the 1954 definition attributes a Darwinian evolution to folk music (DMcG 26 Mar 11 - 04:14 AM) got me thinking. Perhaps to extend the analogies further one should apply a Linnaean binomial classification to "folk". If I have my science right, the genus is an inclusive group but the species is an exclusive group. This means that the generic taxon looks for any similarities that may be shared and "things" get added to the group if they share enough common attributes. The specific taxon is exclusive and works by excluding "things" on the basis that they have something different from any other specific taxon.
Linnaeus decided that using local names (in our case English) for classification would not work because these meant different things to different people so he chose Latin, as a "dead" language, where word meanings did not change. Thus you have terms like "viridis" which was applied instead of "green" (e.g. Hydra viridis). As time progressed descriptive specific names were replaced by latinised versions of the person who first discovered/described that species (e.g. Spartina townsendii). {Apologies - I can't get the computer to do italics}

Thus all music could be generically "folk" but when you get to the specific bit you throw out the kinds of music/song that are not the same into separate taxa and then name accordingly. Your own version/species of music/song within the genus "Folk" can only join another "species" in that genus if all who are already in that species agree that it does not have anything different from their own versions; if they don't all agree you stay in your own species.
You could be "Folkus lloydii" or "Folkus donovaniensis" or even "Folkus suibhneastrayus" or "Folkus whittleus" (not an attack on these contributors' views, just names chosen for illustrative purposes of two here who seem to have fairly strong and clear views).

This classification system should keep everyone happy – if you want to you can be the only one in a species but if you want to join with a pre-existing species of folk music you would, by definition, agree with the others in that species. On the other hand, that might end the discussions and then where would Mudcat be?