The toughest lesson to draw from the Whitehaven tragedy is that there might be no lesson at all. We cannot stop people having rows at home or work, taking leave of their senses, finding a gun and going berserk. Such things rarely happen. But even the most authoritarian state must allow some personal liberty, and everyone accepts the resulting risk. No free community can be wholly safe without losing its freedom.

There is now a widespread belief that the bonds of private responsibility that should tie together neighbourhoods and nations alike have eroded. This is put down to everything from the nanny state to benefit dependency, risk aversion, disrespectful youth, too much money and obsessive security. When the bossy Labour minister Ed Balls banned pictures of children in schools and vetted parents for sex crimes, the bounds of public sanity were strained. Yet no one stopped him. People muttered, "Well, you can't be too safe."

On every First Great Western train, an announcement is made after each stop telling passengers to look about for suspicious people or parcels and report them immediately to the police. It makes for a miserable journey. If you enter a government building, you are told that the current alert status means an imminent terrorist attack is "highly likely". This serves no purpose but to frighten people into conceding the Home Office ever more power.

I would be surprised if former ministers David Blunkett and Charles Clarke were not penning articles claiming that Whitehaven "proves" the need for identity cards and wider criminal checks. Goaded by the media, officials will be drafting papers requiring all guns to be banned, all taxi drivers tested for mental instability and all disputatious families reported by their solicitors to the police. That way we can dump all our cares and woes on the state and claim they are no responsibility of ours.

The most quietly sensible decision taken by David Cameron since reaching Downing Street was to face down the most insidious lobby in government: the police and security services. He refused the motorbike outriders beloved of Tony Blair and Gordon Brown to get them screaming through the London traffic. He also said it was absurd not to walk the 200 yards from his office to parliament. There might be an infinitesimally greater risk in doing so – gleefully dramatised by every newspaper – but he decided to take it. If his protection team found the risk too great, they could always go back on the beat.

What was significant was not Cameron's sanity but the reaction to it. He was not praised for reducing security costs, saving petrol or taking exercise, let alone for bravery. The entire political community, guided by the police, castigated him.

The Times opened its report with: "As the prime minister enters the lobby of the House of Commons, a man emerges from a knot of people, produces a gun and shoots him in the chest. Far-fetched? No, it happened, albeit two centuries ago." Nobody mentions that since then parliament has been turned into a parody of Fort Knox. The reporter pitied bodyguards whose job is now "tougher and more stressful than it ought to be".

Meanwhile, a photograph of the prime minister walking down the street was captioned deploring his "worrying demeanour", which was that he was "deep in conversation and oblivious to any threat or danger". This alarmism was repeated in every newspaper. Each repeated the old saw that the terrorist "only has to be lucky once – we have to be lucky always".

Even Cameron was unable to prevent the police from stationing two guards toting submachine guns outside his suburban home, before he moved to Downing Street. The spectacle in a friendly London street was obscene. Such weapons are unusable in such a constricted space but they associate those who brandish them with personal machismo – as may have played a part in Whitehaven. It takes nerves of steel to refuse this protection, as Lord Baker commendably did when home secretary under John Major. Many ministers (and ex-ministers) retain their armed guards as a sign of status.

Since Cameron came to power, Scotland Yard has been touring Fleet Street briefing against him. Last week Dai Davies, former head of the elite royalty and diplomatic protection branch, said the police were "tearing out their hair because he [Cameron] is being totally cavalier about security". It was "almost an invitation for someone to attack him". Davies's attack is like BA cabin stewards saying their boss, Willie Walsh, wants planes to crash rather than give them more money.

Last week "well-placed police officials" were quoted as preparing a security review of each of the 650 MPs "in the light of intelligence that lone Muslim self-radicalisers may be targeting politicians". This was linked to the unrelated stabbing of the MP Stephen Timms, and to "terrorist chatter" about inadequate security for Britain's world cup football team.

Events such as the G8, the Olympics and the World Cup offer massive paydays for the security industry. Charles Hill, formerly of Scotland Yard's art and antiquities squad, was this week quoted complaining that "virtually nothing" was being spent on security for Britain's museums "during the Olympics", leaving the door wide open to criminals. This is despite the police budget for just two weeks of games having risen to £800m, reputedly dwarfing what even Beijing spent in 2008. The new security minister, Lady Neville-Jones, is said to be "conducting a review" of Olympic security. Might she reduce it?

There appears to be no attempt to assess value for money from an industry that has vastly expanded since 9/11. If an incident occurs, it is a reason for spending more on security. If no incident occurs, it justifies what is already being spent. Britain has little by way of a libertarian tradition to resist the onward creep of the risk-aversion agencies dealing with safety, surveillance and security, all manifestations of a rising public paranoia. Britons instinctively respect central government, allowing it to intrude on their privacy to a degree that would cause riots in more democratic states.

The Guardian today demanded a "full inquiry and published report" into the Whitehaven tragedy, followed by "new laws" to plug any loopholes. Lawyers may rub their hands but it might be better to conclude right away that even in close communities people can go awry and sad things happen. We cannot have public inquiries into every crime.

The public should be invited to reject the politics of fear, that sees life as a perpetual terror of what might happen and a perpetual investigation of what has. It should not be asked to regard every child as a victim and every adult a paedophile, a terrorist or a mass murderer. The government should stop spending stupid amounts of money on a security lobby now running amok through the public sector.

There is no such thing as safe. There is only safer, and safer can require the greater watchfulness that comes with taking risks, witness new theories of road safety. Removing risk lowers the protective instinct of individuals and communities, and paradoxically leaves them in greater danger. But there is no government agency charged with averting that danger. There is no money in it.