Philip Hensher: I've given up Twitter. Should you follow my example?

This week, I left Twitter. It was not a big deal – I'd been on it for three months, mostly to see how it went, and only had a few hundred followers. And then I didn't really like it. I quite enjoyed seeing big news stories unfold in hundreds of comments; I quite enjoyed engaging flippantly with people I actually know. But in other ways, it didn't suit me. I didn't like the way people you didn't know and who evidently didn't wish you well were given personal access to you and your friends. And I couldn't work out what one was doing, really. Was it a conversation? Or was it a sort of newspaper? Was one publishing one's thoughts, or just talking loudly? When it was bad, as it quite often was, it felt very much like shouting like a mad person in a crowded street. Well, anyway, I prefer to save my conversation for friends, so I turned the thing off.

This fundamental dilemma about social media was surely at the bottom of the wavering discussion about whether the government should have the right to turn off the social media during periods of disorder. During the riots, Twitter and Facebook were widely used to comment on the extent of violence. Most of it was "OMG look at the riots on telly". But some of it was very positive, and more accurate and swifter than the mainstream media could manage. I was in Devon without a television or radio, and found Twitter very helpful. For instance, when much of the media were reporting that "Clapham High Street" was in flames, Twitter, with more knowledge on the ground, correctly said it was the shopping centre at Clapham Junction that was affected.

On the other hand, the social media were also being used for not very constructive purposes. A Jordan Blackshaw set up an "event" on Facebook called "Smash Down in Northwich Town". A Perry Sutcliffe-Keenan set up a page called "The Warrington Riots". Neither actually started a riot – in fact, when the idiot Blackshaw turned up to the suggested meeting point, the only people there were policemen waiting to arrest him. Both were sent to prison for four years for incitement to riot.

These stiff sentences must have startled many users of Facebook and Twitter. The law is quite clear about inciting violence and looting, however. When a Johnny Melfah, 16, wrote on Facebook "anyone wanna riot in Droitwich and Worcester... Anyone down for Brum tomorrow, free iPads available [smiley face]", he was clearly encouraging the sort of behaviour that destroys communities for a very long time. How the law deals with someone foolish enough to publish his criminal intentions is not really under debate. But from both sides – the sometimes criminal users of social media, and the authorities trying to deal with these new means of discussion – an understanding of the nature of social media is still in flux. They are both asking the same question that I found myself asking of Twitter. Is this a newspaper, or is it a conversation in a public, or semi-public place?

There is no principle of free speech that applies here. Free speech, in the classic definition, does not allow somebody to shout "Fire" in a crowded theatre. Similarly, no law of free speech would defend someone from publishing the time and date of a proposed looting session. If it were printed in a pamphlet and handed out in a shopping centre, then there would be no hesitation about confiscating it and preventing further distribution. A person addressing a crowd to the same purpose would soon attract the attention of the police.

And a proposed crime may override any right to privacy in a conversation, if it seemed likely to wreak major catastrophe. If we overheard two people talking quietly about a plot to bomb a train, then I don't think we would respect their privacy. Short of that, some notion of privacy might kick in – I doubt any policeman would arrest two teenagers overheard planning a shoplifting expedition, rather than wait until a crime was actually committed. But, even in the most serious cases, if would-be terrorists were plotting over the telephone, would we take away their telephones? If we knew that such conversations were taking place, or likely to be taking place, would we close down the whole telephone network? Why blame and punish the medium of communication?

L ast week, politicians were suggesting that social media should be shut down in extreme circumstances. The government was quick to point out that it did not have such powers, and would not be seeking them. And yet the question hangs in the air. If major criminal activity is being planned on Twitter or Facebook, what is to be done? Is our model here a publication inciting mass violence, which should probably have an order placed on it? Or is it merely a conversation in a public place, where, in the interests of privacy, the forces of law and order should wait to see whether it is just loose talk? There is a difference between a Jordan Blackshaw, and the poor gentleman prosecuted for saying on Twitter, in frustration, that he was going to blow up Robin Hood airport if the airline kept messing him about. But the law does not understand what that difference may be, and I think neither do the users of the social media.

The users of Facebook and Twitter were absolutely clear in their mind that they were conducting a private conversation among their friends and peers. Those who maintain public order were equally pretty clear that what they were dealing with was the online equivalent of an anarchist pamphlet calling for mass violence. Neither is quite correct. W H Auden, years ago, said something to the effect that the trouble with modern life is that people had forgotten the difference between perfect strangers and their dearest friends. It is hard to think, nowadays, what exactly he could have been talking about. So abundantly have the social media fulfilled his prophecy that life before their creation seems, retrospectively, to have been a paradise of separation, of private and public faces kept sharply apart.

The scenario before us – a frightening or inspiring one, probably depending on your age – is that these social media are not a conversation. Nor are they a publication. Still more alarmingly, they may not even be something in between the two states. They may very well be something entirely new. It is for all of us to work out what that may be – psychically, personally, communally. As the hapless teens of Northwich and our confused lawmakers are discovering, we are also going to have to discover what that "something new" means in terms of law. In the meantime, we can always remember that you don't have to be on Twitter, you know.