Walt Whitman was delighted to read a rave review of his book Leaves of Grass in The United States Review of 1855. “An American bard at last,” declared the anonymous reviewer. Whitman's pleasure at this encomium was apparently undimmed by the fact that he had written it himself.

Anonymity has a long tradition in English letters. It can be a blessing and a curse, a vital form of protection and an opportunity for corruption, flattery and revenge.

Anonymity is also one of the defining features of public discourse in the internet age: of the millions of people posting comments on blogs, discussion boards and in other forums, most choose not to identify themselves, but prefer to opinionate under a pseudonym. The cloak of privacy is what gives much internet discussion its raw energy, with a great cacophony of unidentifiable voices competing on equal terms. But unnamed writing is also responsible for some of the worst internet vices: intemperate “flaming” of opponents, bullying, dishonesty and a general coarsening of language and incivility. Not to mention self-congratulation and score-settling.

People behave badly when they think they are invisible. Masked balls were an opportunity for licentious behaviour in a buttoned-down society because (supposedly) no one knew who was who. People who would not dream of being rude in day-to-day transactions feel no such constraints behind the wheel, because the four walls of the car offer the illusion of anonymity; in my experience, drivers with tinted windows are far more aggressive than those without.

In one sense, the fluid notion of identity on the web marks a return to an earlier age. For much of human history, most writing was published without a genuine signature. Anonymity was a defence for authors fearing economic or political reprisal; a male pseudonym allowed the women writers George Eliot and Georges Sand to circumvent the sexism of their day.

In repressive societies anonymity remains a vital shield. Outspoken bloggers in Iran would not dare to operate under their own names, and even with a pseudonym they risk being traced and silenced. The whistleblower, too, finds the necessary courage in namelessness.

But these are the exceptions. For many, the anonymity of the internet is an opportunity to voice opinions, sometimes of the most vitriolic or self-serving sort, without accountability. Last year, a commentator calling himself “Sprezzatura” on the discussion board of The New Republic lavished suspicious praise on the magazine's culture critic, Lee Seigel. “Seigel is brave, brilliant...Seigel is my hero,” wrote Sprezzatura who turned out, inevitably, to be Seigel. But for every Sprezzatura exposed, there are countless others, secretly pushing an agenda from behind a mask.

The self-puffery of writers may be forgivable (Sir Walter Scott and Anthony Burgess reviewed their own books, and even James Joyce collaborated on a review of Finnegans Wake.) But in addition to undermining the credibility of internet discussion in general, the abuse of anonymity can have serious consequences in the offline world: company directors using the cover of an internet “handle” to attack rivals and promote their own companies and financial interests, targeted attacks on named individuals by unnamed opponents, and anonymous harassment. According to a new survey by the University of Maryland, female participants in chat rooms receive 25 times as many sexually explicit, malicious or threatening messages as men, most of them anonymous.

This year, two celebrities in South Korea reportedly committed suicide after a spate of cyber-bullying, prompting the Government to pass laws requiring individuals posting comments through big internet portals to provide their real names. That is excessive. Insisting that every participant in online debate be identifiable is neither desirable nor possible. What is required is a cultural, not a legislative, change, and balanced monitoring: many websites, including Times Online, already moderate all comments, rejecting those which are illegal or abusive.

Most sites accord equal prominence to anonymous postings and those whose authors have identified themselves. Yet the writer who puts his or her name to an opinion is performing a qualitatively different function from the anonymous contributor lobbing incendiary devices from behind an electronic parapet.

We should be far more aware of that distinction. As in society, freedom is balanced with responsibility. If all websites created separate rooms for named and anonymous commentators, it would not be hard to guess where the more elevated debate would take place. Anonymous commentary should be treated in much the same way one might regard, say, an unsigned letter in The Times (an impossibility), or someone who takes part in a community discussion group wearing a wig and dark glasses.

T. S.Eliot favoured anonymity in reviewing, but conceded that “some things are permissible when they appear over one's name which become tasteless eccentricity and unseemly violence when unsigned.” That eccentricity and freedom are what attract some to the blogosphere, but just as many people, I suspect, are deterred from joining in by the unseemly violence that too often accompanies anonymity.

The information superhighway is still a place of thrilling high-speed argument-chases with little policing, but one way to cut down on road rage and establish some sort of highway code is to encourage named drivers while sceptically steering clear of anonymous road hogs who drive with one hand on the horn.

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