Whereas previous generations panicked about knife-wielding teddy boys, sexually lascivious rockers, drug-fogged hippies, heroin-injected inner-city youths and drunken town centre rabbles, now the concern is that the kids are not appropriately discreet in their data handling. I'd like to have heard The Who write a song about that.

Google boss Eric Schmidt warned this week that when they grow up, many young people are going to want to change their names, so desperate will they be to dissociate themselves from the trail of personal revelations they are casually leaving behind them on the web. It is ironic that the same digital culture that is accused of shortening attention spans is keeping our past selves alive and present for much longer than the analogue, biological world ever could. We are hurling thousands of digital boomerangs out into cyberspace, not realising that, it might take years, but they will return.

Some may hit us on the head much quicker. Facebook this week launched its Places app, which like the already popular Foursquare and Gowalla allows your friends, or what passes for them online, to know exactly where you are.

This willing surrender of privacy seems shocking to many. But what is so wrong with this data promiscuity? Many of the concerns are purely pragmatic. That stag night photo might make your interviewer think twice about giving you a job; all that personal information might allow a fraudster to thieve your identity; revealing your location in real time might make you vulnerable to attack or a burglary.

These are real concerns, if somewhat exaggerated. But there is a sense that in giving up so much privacy we are assaulting something of profound importance in our individuality. That something is not privacy in and of itself. For most of human history, people have lived in fairly small communities where everyone knew everyone else's business. You wouldn't need Facebook Places to tell you where John Smith was – everyone would know. The idea that your birthday or occupation might be things you didn't want to share would seem absurd. In that sense, the past 100 or so years have been an anomaly, and open web profiles are a reversion to the norm.

Why did this anomaly arise? There are two factors: a value and the social conditions for that value to thrive. That value is individual autonomy, the strict meaning of which being self-rule. Autonomy is arguably the fundamental value of the Enlightenment. Liberty is politically paramount because without it, we cannot exercise the autonomy which gives dignity to human life.

Ideals can't take hold, however, unless social conditions enable them to thrive. Autonomy has flourished only because democracy, the nation state, greater ease of travel, the weakening of ecclesiastical authority and increased wealth are all conducive to its doing so.

On the face of it, nothing about the growth of social networks threatens this autonomy. Indeed, every time concerns are raised about privacy implications of Google, Facebook or Twitter, the apparently decisive reply always comes back: the information is given out only if users agree. If the choice is always yours, how can your autonomy ever be under threat?

To answer that, we need a deeper understanding of what autonomy requires than simply the ability to make choices for ourselves. Autonomy is in essence a matter of sovereignty over the self. Your thoughts, your beliefs, your life are the business of others only in so far as you choose to make them so. This can easily sound platitudinous today, but in many, if not most, times and places, it is heretical. The orthodoxy has tended towards the opposite ideal, whereby an individual is first and foremost a member of community and enjoys only so much autonomy as that community grants. To decide your own religion, political allegiances or even spouse is outrageous, a hubristic usurping of an authority that lies outside the self, not in it.

In reality, of course, no individual is entirely autonomous, just as no society has denied all autonomy. Nevertheless, societies have sat at different ends of the spectrum, and towards the poles, the differences are real and important.

It has become apparent over recent decades, however, that there is a great deal of dissent about the wisdom of being as close to the autonomous end as Western societies have tended to be. Communitarian thinkers like Amitai Etzioni, Michael Sandel and Alasdair MacIntyre have questioned the stress we place on individualism and have championed the claims of culture and society to have more authority in the regulation of public and private life.

Looked at in that way, the willingness of so many people to give up so much personal information to social networks does not seem surprising. From the point of view of history, it is the desire to withhold so much from public space that is unusual, not to share it. The embrace of social networking could be seen to support the communitarian claim that people value belonging much more than the ideal of the autonomous liberal individual supposes.

For those who still believe in the value of autonomy this presents a real challenge. People remain attached to individual choice, but this is not the same as a deep commitment to autonomy in its full sense. The problem is that people aren't even aware of the difference, and that by making what seem to be free, autonomous choices to share information, we might unwittingly undermine our own autonomy.

How could this paradoxical situation arise? Think for a moment about what the cumulative effects of a highly open, networked life might be. Facebook lives are lived under the constant scrutiny of others. We even internalise this, by thinking about how we might tweet an experience even as it is happening. Just as the desire to capture holiday moments on camera can stop you looking properly at what is in front of you, so the desire to share online could stop you seeing things simply from your own perspective.

Being so connected so often could therefore foster a self-image which is defined by our place in the network. In that way, it undermines the ideal of autonomy by reviving the idea that we are first and foremost members of communities, and this risks breeding conformity. When the norm is to be connected we can lose sense of ourselves as independent individuals.

It's too soon to say just how well founded these worries are. But as Eric Schmidt said, "I don't believe society understands what happens when everything is available, knowable and recorded by everyone all the time." To acquire this understanding, however, we have to think about more than just pragmatic issues of security and confidentiality.

When we do, it should be clear that privacy is not a self-evident value, nor is it self-evident what should be private and what shouldn't. It is also clear that the ability to personalise and make choices is not the same as the capacity to make truly autonomous decisions. Furthermore, it is clear that the relative importance of the community and individual is up for debate. For these reasons, those who think that the autonomy of the individual is the greatest triumph of the Enlightenment need to think hard about how social networks might undermine it.

^Independent