SS, you haven't addressed my point, which is that your contextual definition tells us precisely nothing..

I disagree, Howard - I think it tells us all we need to know.

If "folk" is what happens at a folk club, and (as you've also told us, apparently with pride) anything goes at a folk club, then what's the point of calling it anything?

Well - there must be a point, otherwise the word wouldn't have any value. That the word has value can easily be demonstrated so perhaps its meaning is its value? Certainly it has greater value that it does meaning, as, in effect, it can mean everything, and nothing, and yet it still has value. I see a Folk Club advertised and I know, pretty much, what I'm in for - and seldom am I surprised or disappointed because whilst anything does, indeed, go, there is an Familiar Overarching Living Kinesis which I feel, just possibly, might well be the very context of the thing and the willingness of those therein to engage with one other in a name of the principle of value, if not meaning, in which they are gathered.

If exactly the same thing is taking place down the road at something which doesn't call itself a folk club, is that still "folk"?

It wont be exactly the same because it's not being done In the Name of Folk. As I say, I go to such events from time to time and perform Traditional Balladry almost as a form of studied classical music, something along the lines of Piobaireachd perhaps, but it's not Folk Music, and it doesn't feel like folk either.

To pick up on an earlier example, I don't believe that an operatic aria, performed half-heartedly or not, can be "folk".

I have experienced otherwise. This is the thing with folk - it is, essentially, empirical; very much a matter of being there, or even seeing is believing. Same with Hotel California - it happens, I know it does, but these days I take it as a cue to head for the bar. I'm not saying it's good, all I'm saying is it happens.

It is conceivable that it might be re-interpreted in a folk style and that might make it acceptable to some folk audiences, but it still doesn't make it "folk".

In my experience folk audiences aren't in the least bit discriminating - except when it comes to Traditional Balladry of course. I've seen them giving warm appreciation to all shades of singer / songwriter schlock, piss-poor pop covers and Bob Dylan sing-a-longs, but bristle with barely repressed hostility when someone has the temerity to sing an unaccompanied ballad of a greater duration than 5 minutes.   

To draw a parallel with an earlier example of mine, Swan Arcade's version of "Lola" was acceptable to folk audiences because of the style, but that doesn't make "Lola" a folk song.

Please be so good as to define what you mean by Folk Style.

If you admit your would-be opera singer as "folk", what do you do when he turns up the following week with 20 of his mates and wants to perform "La Boheme"? You can't tell him it's not appropriate, you've already re-defined it as folk. But is that what your audience wants, or expects, to hear?

Again you're dealing in hypotheticals, Howard. Folk isn't a matter of hypothesises, it's a matter of experience. Folk is as Folk does. If it happens, then fine, but it never would. Just as Meatloaf isn't about the turn up and sing Bat Out of Hell - but Jim Eldon might, in which case it is very much folk music. Hold on - I've just had a vision of Jim Eldon performing La Boheme in its entirety...   

The reluctance of the folk world to draw boundaries means that it has become the remedial class for those musicians who don't play folk music but lack the talent, or more likely the inclination to work hard at their music, to be admitted into other venues.

Not true. I know a lot of fine & gifted amateur players & singers. In fact I don't listen to professional folk musicians simply because I don't have to - I know where to go to hear my favourite singers and players because they are right there in my favourite folk clubs. Granted there are lesser musicians and singers, but its never an issue - not with me anyway - and I wouldn't never be so inhumane dismiss anyone with the language you've used here. Shameful so it is.

There are plenty of opportunities for amateur musicians, including brass bands, choirs, amateur orchestras and operatic societies. However most of these demand high standards of musicianship, and expect their members to work hard to achieve and maintain these. It's only the folk world which allows, in fact sometimes encourages, poor standards. It's bad enough when this applies to folk music, we shouldn't allow musicians from other genres to take advantage.

When I say Folk Music is Defined by Context, I don't mean we get renegade tenor horn players sneaking in because they've been given the boot by the local brass band. I've never experienced anything like this. It's the Folkies themselves who do the borrowing, although I've known a few otherwise Professional Musicians who are also folkies - classical singers, for example, who might come down to the local singaround and sing a few ballads or traditional songs, and who might, if drunk enough, and with enough encouragement, sing something operatic. But never is it a matter of poor standards.   

Leaving aside what is meant by "designated", this still leaves the problem of defining what is meant by a "folk context" - even if it is just a gathering together of people with intent to commit folk

You can't leave Designated out of the equation - this is the Invocation of Folk that determines the context; it is saying that what will take place here will do so In the Name of Folk. Defining a Folk Context is, therefore, largely a matter of designation. From the available evidence a Folk Context is where Folkies gather to play and listen to live music of a number of possible genres which might fall under the umbrella of Folk Music simply because they're acceptable in a folk context.
   
this still demands some understanding of what "folk" means, which brings us back to where we started, needing some sort of definition.

Maybe Folk doesn't mean anything at all, or else, more likely, maybe it means all things to all people, though there is an evident consensus amongst Folkies that it must mean something otherwise they wouldn't use it. However, when one tries to explore what Folk might mean, one is directed to the 1954 Shibboleth which hardly suffices for the amount of music on offer In the Name of Folk in any given Designated Folk Context. So we move on to Folk as Philosophy, Folk as a Feeling, Folk an an Overarching but Essentially Meaningless Aesthetic, Folk as a Societal Opiate, Folk as Political Union, Folk as a Gathering of Similar but Essentially Disparate minds, or even Folk as Familiar Overarching Living Kinesis.

Essentially, it is my belief that Folk doesn't need a definition simply because, from the available evidence, Folk is quite happy to be undefined.