It is commonly believed that the advent of the Internet has been a boon for free speech. No longer do the mainstream media act as the exclusive gate-keepers of public opinion. Anyone with a point of view can set up a website and start publishing. Online news and analysis sites like Crikey, New Matilda and On Line Opinion have proliferated.

Dozens of well-read blogs provide an outlet for a plethora of views that would rarely have found their way into newspapers or onto the airwaves. Mainstream news organisations have been forced to establish their own online opinion and comment sites open to the public. Everyone with something to say can go online to say it and be sure that someone will be reading.

The Internet should represent a great flourishing of democratic participation. But it doesn’t.

An ugly culture of dogmatic and belligerent interventions now dominates social and political debate on the Internet. Comment sections on Internet forums are blighted by a kind of cyber-rage that drowns out debate with table-thumping assertion and a style of personal engagement that owes more to Gordon Ramsay than Socrates.

A new vocabulary has developed to describe the variety of offenses, with neologisms such as “flames”, “trolls”, “snarks” and “sock puppets”. Moderators of blog and comment sites do their best to control the rage by setting rules against racism, sexism, coarse language and ad hominem attacks.

John Quiggin’s blog, one of the best, bans those who flout the simple rules of courtesy. An indication of what he is up against is suggested by his seventh rule:

In the event of a ban, do not attempt unauthorised posting of comments, or harassment through email, phone contact or other methods. Be aware that any such action will lead to an immediate and permanent ban from this site and exposes you to a range of civil and criminal sanctions.

You can be sure these rules were developed after a long and painful period of failed attempts to maintain civility through appeals to self-control. While a few defamation suits may have been avoided, the rules have had little impact on the ugly culture of the net.

Many have entered into a public debate on a website only to find themselves the target of a torrent of abuse from the regular army of anonymous users who have no respect for any higher principle of free speech. Their attitude is: “if you don’t like the heat then get out of the kitchen”.

The truth is that large numbers of people who would like to participate in Internet forums are driven out because they find the experience unpleasant and upsetting.

Even a public commentator as thick-skinned as Peter Faris declined a request from Crikey to join its blog, citing the unpleasant attention opinion writers invite: “Crikey will find that some contributors will not want to expose themselves to this sort of hate and abuse …”. Crikey is by no means unique on this score.

The brutality of public debate on the internet is due to one fact above all — the option of anonymity. The belligerence would not be tolerated if the perpetrators’ identities were known because they would be rebuffed and criticised by those who know them. Free speech without accountability breeds dogmatism and confrontation.

Moderate opinion tends to be based on a more nuanced and thoughtful view of the world and is more inclined to consider alternative views. Yet these are precisely the contributions excluded from discussion by the bullying culture of online forums. There is little scope for the back-and-forward of debate when the normal social rules of respect and reciprocity do not apply.

To be sure, there are corners of the World Wide Web where communities with common interests engage in civilised discussion, where opinions are formed and changed. Yet there is always a danger that these polite exchanges will be gate-crashed by an opinionated cyber thug roaming the net.

If free speech means no more than the absence of restrictions on people using public forums to say whatever they want, and however they want, then the Internet is the promised boon. But if free speech means encouraging a free-flowing dialogue that draws the public into an exploration of alternative ideas and enriches civic culture, then the Internet is its enemy.

Clive Hamilton is professor of public ethics at the Centre for Applied Philosophy and Public Ethics.