Is social media changing from a 'buy' to a 'sell'? I'm not talking about share prices - social media businesses no doubt have billions in profits to come - but rather about the market in ideas about what they do.
On the face of it, things could hardly get hotter. To take three random examples: the Queen is 'on Facebook' (sort of); Mark Zuckerberg has been immortalised on the big screen in The Social Network; and Twitter has appointed someone to teach members of Congress how to tweet.
More important, in the next three years the number of people online globally is expected to rise from 1.5 billion to 2.2 billion. That's a lot of extra Twitter and Facebook accounts - and a lot of new 'friends' and 'followers' for those already online to sign up.
But there has been so much enthusiasm among the twittering classes that there's an emerging market for social media sceptics. And some big names have been taking up the challenge - and earning themselves some good old-fashioned freelance fees from traditional media.
Most recently, British novelist-turned-US-academic Zadie Smith (below) delivered a powerful broadside in the New York Review of Books. Smith identifies herself as a fellow Harvard alumnus of Zuckerberg, and his reluctant customer:
"I quit Facebook about two months after I'd joined it. As with all seriously addictive things, giving up proved to be immeasurably harder than starting. I kept changing my mind: Facebook remains the greatest distraction from work I've ever had, and I loved it for that."
But it's not just the time-wasting: her objections are deeper and more existential than that. She feels Zuckerberg's creation reveals his view of human nature, which is altogether alien to her's:
"We have different ideas about what a person is, or should be. I often worry that my idea of personhood is nostalgic, irrational, inaccurate. Perhaps Generation Facebook have built their virtual mansions in good faith, in order to house the People 2.0 they genuinely are, and if I feel uncomfortable within them it is because I am stuck at Person 1.0. Then again, the more time I spend with the tail end of Generation Facebook (in the shape of my students) the more convinced I become that some of the software currently shaping their generation is unworthy of them. They are more interesting than it is. They deserve better."
Specifically, the world of Facebook is "falsely jolly, fake-friendly, self-promoting, slickly disingenuous". And "when a human being becomes a set of data on a website like Facebook, he or she is reduced. Everything shrinks. Individual character. Friendships. Language. Sensibility. In a way it's a transcendent experience: we lose our bodies, our messy feelings, our desires, our fears."
And, with her Harvard experience to draw on, her interpretation of what Zuckerberg has made goes back to his personality and circumstances:
"Everything in [Facebook] is reduced to the size of its founder. Blue, because it turns out Zuckerberg is red-green colour-blind. 'Blue is the richest colour for me - I can see all of blue.' Poking, because that's what shy boys do to girls they are scared to talk to. Preoccupied with personal trivia, because Mark Zuckerberg thinks the exchange of personal trivia is what 'friendship' is."
Smith's call to arms: get a real life. "Step back from your Facebook Wall for a moment: Doesn't it, suddenly, look a little ridiculous? Your life in this format?"
Her diatribe follows that of an even bigger fish in the world of opinions. Malcolm Gladwell is one of the smartest commentators on the contemporary scene. You don't want to find yourself on the opposite side of an argument with him about which way the wind is blowing.
In last month's New Yorker, Gladwell turned a sceptical eye on claims for the revolutionary impact of Twitter. He compared the disciplined activism of the civil rights movement in the US in the 1960s with the supposed role of Twitter in the student protests in Iran last year. English-language hashtags like #iranelections, so often cited in Western media, he points up, only tapped into outside, English-speaking observers.
It was only with high personal motivation, through real personal contacts, and a command-and-control hierarchy based on the church network, that the civil rights movement achieved many of its goals.
In contrast, social media are networks, binding people together with loose, consensual ties and not under the control of a central authority. As a result they "are effective at increasing participation - by lessening the level of motivation that participation requires".
So, imagining the impact social networks might have had on the ability of Martin Luther King to organise his supporters in Birmingham, Alabama, Gladwell, he is dismissive:
"The things that King needed in Birmingham - discipline and strategy - were things that online social media cannot provide ... and of what use would a digital communication tool be in a town where 98% of the black community could be reached every Sunday morning at church?"
He concludes: "The instruments of social media are well suited to making the existing social order more efficient. They are not a natural enemy of the status quo."
None of this questions the value of social media for journalists: finding out what people are communicating will always be useful. But it is a word of caution about expecting to eavesdrop on revolutions in the making.
As for the place of social media in our consciousness, well, it's easy to think that today's media attention will be a permanent fact of life. But we aren't preoccupied with eBay as we were in 1998, Google as we were in 2004, or MySpace as we were in 2005. They're all still here - just not quite as fascinating or all-powerful as they once seemed.
For a final bucket of cold water on social media hype, I refer you to a book Zadie Smith quotes with approval: You Are Not a Gadget: A Manifestoby the distinguished fifty-something technologist Jaron Lanier. Lanier's beef is with the lazy assumption that our online existence is simply life in a different medium. This, says Lanier, is:
"a philosophical mistake ... the belief that computers can presently represent human thought or human relationships. These are things computers cannot currently do."
Lanier warns us not to limit our idea of ourselves, or human potential, to the version presented to us by Twitter or Facebook.
Go on, 'share' that with your 'friends'.
