By another view it's commons music - a space where there's no social distinction between performer, patron, and audience. Reflecting in this way the universality of human experience folk can transcend it's local roots, cross continents and speak to more distant cultures.
Whereas rock, for example, is at least partly about the liberating, anarchic rebellion of noise, and jazz is about pre-conscious expression, folk is principally about the vocal message, so the instrumentation is decoration. The acoustic guitar is the instrument of choice generally, as it's about the most versatile instrument there is. You can hitchhike with a guitar. You can play one quietly in a corner, or loudly in a bar. It has a large range of tonality. It's simple to learn, hardy, and it's cheap to maintain.
The more strident would argue that the 'western' part of the definition is simply a quiet form of racism, which implies that 'foreigners' make a different, more exotic and strange form of music which is not folk as 'we' know it. This seems unnecessarily argumentative - a more generous spirit would say that our definition of folk as western is simply the natural result of our historical development and long familiarity with our own common form.
There's been a resurgence in folk in the past decade, and it's spiritual influence has spread through much of popular music. My thesis (which I completely accept is unscientific and poorly researched, ok let's call it a pub theory) is that the crossover appeal of new folk began with Jose Gonzales' backings for the Sony ads, which somehow touched a raw nerve in western culture. We're in an age where there's 24 hour news, wars and disasters, and greater or lesser moral chaos everywhere. All the big social ideas of the last century have been discredited, but crucially, there's no emergent, darwinianly stronger, philosophical world view to cling to. As such we're somehow in psychic limbo in a tarnished, messy world. It's this rift which has bred a yearning for the mental-cosy-log-fire reassurance of a music which is simple, clean, and uncomplicated (i.e. unsophisticated?).
The slow, soothing, timeless harmonies of Fleet Foxes are probably the gold medal winner in this space. Equally you can see the ever growing, persistent interest in the authenticity of world music. Or the enormous, baffling success of Seasick Steve's blood-raw blues (not some digitally hyper-processed, post-modern, reality show mangled, iBlues - but actual, authentic, blues?! in the 21st century! It's quite incredible.).
It's an example of quite how endearingly strange we are as a civilisation that in this globalised, digitized, compressed and homogenised age, an album as far out of it's own time as The Wild Hunt, by the awkwardly monikered The Tallest Man on Earth, can be made anew. If you've not heard him before then you'll immediately be struck by the voice - as raw and sharp as a flesh wound from a rusty nail - it keeps grabbing your attention, but it also detracts from the strength of the songwriting. The songs sound as if they were written in an empty carriage of a freight train by a stowaway hobo, and then recorded in a motorway underpass. TTMOE is clearly in thrall of Dylan's early Bob Dylan and The Freewheelin' Bob Dylan. Still, if you're going to choose a hero, you may as well make him one of the greatest ever. It's a fine compliment to TTMOE that the result is not laughable in comparison, particularly on the eloquent "Love is All" - his emulative version of the Dylan classic "Don't Think Twice (It's Alright)". There's real talent here, both poetically and musically. For most of the album he accompanies himself with fingerpicking a small, hard bodied acoustic guitar, and there's no intimate introspection here - the songs are belted out like a busker competing with passing buses and aeroplanes. "King of Spain" is a cheerful daydream about escaping to a new life in the wild south. The highlight of a relatively brief 10 song suite, is the final "Kids On The Run", with heavily reverb'ed and wistfully melancholic piano usurping the guitar.
Laura Marling is an artist that seems to straddle a raft of apparent dualities. She's a European girl singing melancholy country-folk, like long-lost Joni Mitchell songs. She's a deep, mature voice - on a surprisingly young head. Highlight's run throughout the album and there's nothing you should miss, but in particular there's the fallen but unbroken "Rambling Man" (But give me to the rambling man, let it always be known, that I was who I am...).
Links:
TTMOE - "Burden of Tomorrow" - http://www.npr.org/templates/story/story.php?storyId=126739806&sc=nl&cc=sod-20100511
Laura Marling - "Goodbye England (Covered in Snow)" http://www.youtube.com/watch?v=lUi9teTRCgk
If you like this, also check out Diana Jones: http://www.youtube.com/watch?v=Numk9kXDV1o