When a moral panic erupts and due process breaks down,we know it as ''mob rule'' or''mob justice''. But scurrility can take over the body politic without the mob-that is, ordinary people -having much to do with it.
While Joe McCarthy was hunting real or imagined reds in 1950s America, he was a senator. Among his tenacious helpers was Richard Nixon, a future president. Congressional committees and intelligence agencies were complicit. McCarthyism was an elite phenomenon before it was a popular one. The accused were failed by great institutions of state, not a rampant citizenry.
In recent years, Britain - sane, rigorous, legalistic Britain - has succumbed to a sexual McCarthyism, with paedophilia substituting for Soviet affiliation.
Like McCarthyism, it sprouted from warranted grievances: There really were unpunished incidents of child sexual abuse in British public life, just as there were traitorous communists in post-war United States. Like McCarthyism, healthy vigilance curdled into something dark and hysterical. And like McCarthyism, the carnival of defamation cannot be blamed on the lumpen masses.
Populist fevers are easy to disregard as nuisances of democratic life; they come and go every few years. Britain's problem is more troubling than that. Some of its most important institutions - the police, the media, elements within Parliament - have simply forgotten how to do their jobs. They have unlearnt some of the country's best habits - fairness and discretion.
This week, the Metropolitan Police admitted that it should not have described allegations of a paedophile ring in 1970s Westminster as "credible and true" before the force had even concluded an investigation into it.
Over the summer, Wiltshire police brought camera crews to the gates of Mr Ted (Edward) Heath's old home, where they invited victims (not "alleged" victims) to come forward with allegations against the deceased former prime minister.
Mr Heath joins Mr Leon Brittan and Mr Alistair McAlpine as eminent politicians of an earlier time whose names have been stained by over-publicised hearsay. None can defend himself from beyond the grave, though Mr McAlpine received damages from the BBC and irresponsible rumour-mongers in the last years of his life.
Mr Paul Gambaccini, a radio broadcaster, spent a year on police bail, unable to work, before being told there was no case to answer. His account of the ordeal and the authorities' behaviour blends Kafka with the low farce of the Naked Gun trilogy. Another celebrity, Cliff Richard, had a police raid on his house broadcast live by helicopters from the BBC, which had been tipped off by the local constabulary.
In 2012, Mr David Cameron was handed a list of alleged paedophiles to investigate by a simpering daytime TV host - the Prime Minister refused to play along. A few MPs have served as the parliamentary wing of this slapdash crusade. One is now deputy leader of the Labour party.
When the history of these years is written, "populism" and "mass hysteria" will feature among the culprits, because they always do.
This is too easy. There are no crowds outside Parliament and Scotland Yard egging the crusaders on. If voters are worried about conspiracies of high-powered pederasts, they do not mention it to pollsters who record the popular concerns of the day. MPs do not report mailbags straining at the seams with letters about the subject. It would be remarkable if one in 10 people in Britain even knows who Mr Brittan and Mr McAlpine were. Mr Harvey Proctor, a former MP, was no household name until he went public to defend himself.
This is an inquisition of powerful people by other powerful people. It is driven by supply, not demand. The public's only complicity is as the audience to which these grandstanders are performing and, even then, it is not obvious that we are actually watching. The elites are giving the mob a bad name, not the other way around. There is no vigilantism here.
The generous interpretation is that institutions which failed to act against real and heinous sexual abuses in the past are now trying too hard to atone. Every showboating press conference and lurid documentary is a sincere effort to show that they "get it". If they are destroying lives in the process, it is because they care too much.
So many British pillars have tottered or fallen in the past decade - the phone-hacking press, the expense-fiddling Parliament, the crash-causing banks - that our elites have become vigilant to the point of hysteria. Nobody wants to go down in the next scandal, and a few know that a grand reputation can be coined by uncovering it, whatever "it" turns out to be. In principle, this is a healthy thing for a country to have: an establishment that treads fearfully and turns on its own.
But there is another, less cheering interpretation. Some people in public life are second-rate or malign, or both, and cloak these flaws under the dignity of their office. And because of them, not the mob, Britain's civilisational glories - its rule of law, its respect for the individual - are more precarious than we think.
In Mr Gambaccini's account, there is praise for ordinary Britons who stopped him in the street for pep talks. And there is seething disdain for institutions that turned out to be less impressive than they sounded. He says of the Crown Prosecution Service: "It's time to stop respecting it just because it has the word 'Crown' in its name." The hounded victims of McCarthy might have said the same of the US Senate.
A good definition of an "institution" is something that transcends the individuals who work within it. But this is only true up to a point. Recent years have shown that it does not take many fools or knaves to debase the DNA of an august body. When they do, it is snobbery to start blaming ordinary people.
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