Until now, the anarchic and unruly realm of the blogger has been seen as a somewhat surreal world remote from real life. It has at last impinged on mainstream British politics in no uncertain fashion. The malicious blogging ambitions of a couple of Labour Party zealots, one inside 10 Downing Street where the other used to work, have embarrassed the already beleaguered Prime Minister and given his political enemies fresh ammunition to hurl at him. One of the zealots, Damian McBride, was employed as a special political adviser to the Prime Minister, a post created to keep civil servants from having to dirty their hands with party politics. He passed the time dishonourably inventing scurrilous rumours about the leaders of the Tory Party, with a view to his equally dishonourable co-conspirator, Derek Draper, posting them on a pro-Labour political blog to be called Red Rag.

News of this dastardly plot reached an established Tory blogger, known by the pseudonym Guido Fawkes, who sent the material to a newspaper - proving ironically that in the internet age the print media still has a purpose. Mr McBride had to resign in disgrace, and Mr Brown, in his usual cack-handed way, has half-apologised and half-disowned it. All hell was thus let loose on the political battlefield, with Downing Street being described as a "cesspit" and the blame laid firmly, not without reason, at the door of a culture of scurrility cultivated by Mr Brown himself. More than one ex-minister has complained that the distressing experience of being "briefed against" - off-the-record denigration in the press, planted unattributedly by those who have the Prime Minister's ear - has happened to them too. Given the instant hit-and-run anonymity that those who post items on blogs (as distinct from most of those who run them) can enjoy, blogging must have seemed the natural place to expand these nefarious activities. It fits well with the tabloid-driven tendency to reduce all politics to personalities rather than policies.

Blogs - a corruption of web-log - were invented in America, where they still thrive, particularly among the political and religious right wing. What feeds the blogosphere's paranoia is a sense of resentment that "they" - those in charge - are engaged in a conspiracy against "us" ordinary folk. The main media is regarded as part of that conspiracy, which is why the internet - cheap, unregulated and with unlimited capacity - has drawn the bloggers to itself. In Britain, too, there are Catholic bloggers, again often right-wing, polemical and vituperative. The targets in this case often seem to include The Tablet, in some sort of fantastical conspiracy with the bishops. Generally, blogs are far from an idealised forum for an exchange of intelligent ideas that would be constructive. More often they indulge in straight poison-pen character assassination without reference to any requirements of accuracy or balance.

Suing a blogger for libel can be a frustrating business, and Messrs McBride and Draper must have presumed that the Tory leaders would have had no stomach for it. But eventually the laws of privacy and defamation will have to catch up with this Wild West world, not least by stripping the anonymity which encourages an almost insane recklessness. There is a good subject here not just for libel lawyers but also for psychiatrists and moral theologians. What is it about a computer connection to the web that can turn a Dr Jekyll into a Mr Hyde?