But for some, spirituality is a byword for irrational beliefs and a sense that anything goes.
The comedian David Mitchell mocked the tendency, writing a column imagining a spiritual summer camp. "From reflexology to astrology, from ghosts to homeopathy, from wheat intolerance to 'having a bad feeling about this', we'll be celebrating all the wild and wonderful sets of conclusions to which people the world over are jumping to fill the gap left by the retreat of organised religion."
Alan Miller, director of the thinkers' forum NY Salon, wrote that "'spiritual but not religious' offers no positive exposition or understanding or explanation of a body of belief or set of principles of any kind".
Another group of people likely to be dismissive towards the "spiritual but not religious" mindset might come from organised religion.
"People have wanted to see how they fit into the big picture, which is really fantastic," says Brian Draper, associate member of faculty at the London Institute for Contemporary Christianity. But there's a smorgasbord-like array of beliefs and many are built on "pseudo-science", he argues.
"I don't just choose spirituality as a lifestyle choice to enhance what's there, there's an element of self sacrifice to Christianity. The danger is you use spirituality as a pick and mix from consumer culture."
Humanists are deadlocked over the issue of the "spiritual" category. Andrew Copson, chief executive of the British Humanist Association, accepts that for many people it's a shorthand for saying "there must be more to life than this". But he finds its vagueness unhelpful.
"It can be used for everything from the full Catholic mass to whale songs, crystals, angels and fairies." As a humanist he prefers to avoid spirituality.
Humanism is about the belief "that human beings find value in the here and now rather than in something above and beyond". "People have social instincts and as a humanist it's about reinforcing those instincts," he explains.
I've made my own criticisms of what I, too, see as the consumerist aspects of the SNR phenomenon, so I'll take a different tack this time and say that pace Miller, not everything needs to be capable of being summarized in a list of rational principles or goals to have value; to expand a bit on what Oliver Burkeman says earlier in the article, much of human experience is non-conceptual, beneath the attention of conscious awareness. And pace Copson, not all of us are interested in reinforcing anything more than the bare minimum of social instincts; I, for one, could make no bones about a "spirituality" based upon an inhumanist perspective.
Speaking of species-wide commonalities, though, I suspect there's something fundamental to human psychology that makes us seek security by situating ourselves squarely in the middle of a group. W.H. Auden wrote the lines, "Any heaven we think it decent to enter/Must be Ptolemaic with ourselves at the center." George Carlin noted how, when driving, everyone who goes slower than you is an idiot, and everyone who goes faster than you is a maniac. And Dan Ariely suggested that we only know what we want when we see it in context; like an airplane pilot landing in the dark, we want to see runway lights on either side of us before touching our wheels down. Most of us can probably acknowledge how amazingly often we manage to frame a situation so that we're the only sane, reasonable people involved, beset on all sides by lunatics who fail to recognize our wisdom. Perhaps it's a lingering evolutionary instinct from our days avoiding predators on the African savanna: we intuitively feel it's terribly dangerous to hang out on the fringe.
Along those lines, I'll suggest that the widespread, amorphous concept of spirituality in our culture is an expression of that same quest for stable, safe middle ground. The purpose isn't philosophical truth-seeking so much as psychological comfort-seeking, defining oneself in relation to others rather than by a conceptual pole star.