FILE - This Feb. 1, 2012 photo shows the Facebook logo on a computer screen in Berlin. A published report says Facebook is seeking a valuation of $85 billion to $95 billion when it goes public in a few weeks. The Wall Street Journal, citing unnamed people familiar with the matter, said Thursday May 3, 2012 that the company plans to set the per-share price of its stock in the high $20s to mid $30s. This is a narrower range than the previously expected $75 billion to $100 billion. Facebook's initial public offering will be by far the largest Internet IPO ever, dwarfing even Google Inc.'s in 2004. (AP Photo/dapd, Timur Emek)

For all that we may enjoy self-disclosure, sometimes a dose of introspection can do us good. Photo: AP

I DON'T remember exactly when I signed up to Facebook but it was some time in 2005, when I was a graduate student in England. Facebook was just over a year old, and used exclusively by students in universities in North America and Britain. If you had told me that in seven years' time I'd be writing a newspaper column about its global impact, I wouldn't have believed you. But here I am.

Last Friday, Facebook had its long-awaited initial public offering in the US. What began as a project in founder Mark Zuckerberg's Harvard dorm room is now a public company valued - some say overvalued - at more than $US100 billion.

Facebook joins the ranks of the top 25 listed companies in the US, with a market value that surpasses that of companies such as McDonald's and Ford. About one in seven people on the planet is an active user of the website, including close to half the Australian population. By any measure, it is a remarkable commercial story.

Far more profound is Facebook's social and cultural significance. The conventional wisdom states that Facebook and its social media cousin Twitter are transforming politics as we know it. Many point to the Arab Spring as a sign of how Twitter revolutions and Facebook activism will spread democracy around the world. Technological innovation is supposedly leading us to civic progress.

Whether you subscribe to so-called cyber-utopianism or not, there is one reality that is beyond dispute. Something has happened to the way many of us live and interact as a result of Facebook and social media.

It isn't just that we are constantly ''connected'' to friends and acquaintances. Our embrace of Facebook has involved a radical redrawing of the lines that divide our public and private lives. Things that were once regarded as belonging to the province of one's private life are now regularly broadcast to those outside our intimate circle.

Personal identities have always been defined by a sense of recognition, to be sure; it has always mattered that others recognise us for who we are. But never have our personal identities been so dependent on their public expression. The creeping influence of social media impels us, however insidiously, to believe that nothing is validated as reality until it is either put into a status update or a tweet.

I suspect we're yet to grasp how dramatic this change may be. Those of us who know of a world without Facebook or Twitter may recall a less therapeutic society, in which one's opinion didn't always need to be stated aloud. But will generations that grow up with social media consider privacy and self-containment as quaint notions from an alien past? Will they ever pause to disconnect from the noise and chatter of an online world?

There are reasons for concern. British scientist Susan Greenfield warns that Facebook risks infantilising the 21st-century mind by fostering among its users ''short attention spans, sensationalism, an inability to empathise and a shaky sense of identity''. Some recent research suggests a correlation between using Facebook and suffering from depression.

At the very least, the internet has exposed or magnified our human frailties - particularly of the narcissistic kind.

Neuroscientists in the US have found, for example, that talking about ourselves triggers the same sensation of pleasure in the brain as the reward of food, money or sex. Social media may be liberating our true natures, just not in ways that are always positive.

Indeed, there is something deeply disruptive about the way social media is changing our identities. Individuality was once something that was to be discovered from within. Today, it seems to be all about something to be shown off to others. Authenticity has become inauthentic. Private is becoming public.

There is something we can do.

I think of the American philosopher Henry David Thoreau in the mid-19th century. Confronted with an industrialising society, transformed by the railroad and the telegraph, Thoreau famously retreated to the woods of Walden Pond in Massachusetts, building himself a small house to enjoy a life of rustic simplicity for two years. As Thoreau explained in Walden, a book that documented his experiment in living: ''I never found the companion that was so companionable as solitude.''

My point here isn't to suggest that we substitute some kind of Luddite existence for our permanent connectedness. Short of the woods, it is enough for us to retreat some of the time to a sanctuary somewhere, away from the multitudes and from the world online. Whatever we may think about the value of social networks, we shouldn't forget the value of solitude. And for all that we may enjoy self-disclosure, sometimes a dose of introspection can do us good.

Maybe, instead of logging in to Facebook, we should try finding a quiet corner at home and opening our journals. I think I just might.

Tim Soutphommasane is a political philosopher at Monash University.

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