On Saturday, my teenage niece described how she had seen a boy bleeding to death from stab wounds as she drove home from a party recently. While the adults present talked earnestly about the number of “young people” who have been murdered in London in the past few months, she calmly recited all their names.

On Sunday, I walked into my sitting room and saw a man trying to break into the house through the front window. It was about 8.30am.

It is the biggest cliché in politics that “it's the economy, stupid” that determines the result of elections. It's also the biggest fallacy. Of course voters are cross about the rising price of food and fuel, but it is the sense of chaos in the world around them that really eats into their souls. People know that the economy is like the weather, something that is, at least to some extent, beyond the Government's control. What they really want from politicians is a sense of optimism about creating a different, more orderly, society. During the recent London mayoral elections the word used most frequently by focus group members was “grim”. This covered everything from parking tickets to graffiti, but it was the violence and disorder on the streets that worried them most. It is not just in the capital that people fear for themselves and - more intensely - for their children.

Across the country, there has been a 19 per cent increase in the number of stabbings in the past five years. One in five people between 19 and 24 knows someone who has been threatened by a gun or knife. The party that promises to create a safer, and more civilised, country will win when Britain next goes to the polls.

There has been a strange political reversal in recent years. It used to be the Conservatives who argued that economic stability was the most important thing, while Labour made the case that there was such a thing as society too.

Now, just as David Cameron has overtaken Gordon Brown as the leader most trusted to run the economy, the Tories have started pushing social issues instead. Yesterday, while the Prime Minister was telling us to eat up our mouldy cheddar, the Conservative leader promised to make the “broken society” his main theme between now and the general election. Policies on education, welfare and the family - as well as knife crime - will all be pegged on to the “broken society” washing line. But the real message will be that legislation is less important than a change of culture.

In his speech, Mr Cameron said that people had to take personal responsibility for things such as obesity, drug addiction and alcohol abuse - rather than blaming external forces such as poverty or the state. “We have seen a decades-long erosion of responsibility, of social virtue, of self-discipline, respect for others,” he said. “Refusing to use these words - right and wrong - means a denial of personal responsibility and the concept of moral choice.”

The latest must-read book at Conservative HQ is Nudge, which argues that peer pressure is a more effective way to change behaviour than state directives. Last week Steve Hilton, the Tories' chief strategist, met one of its authors, Richard Thaler, to discuss how his approach could be applied to social problems such as drugs and knife crime. At the moment, the argument goes, people are being “nudged” in the wrong direction, with rap music that glorifies violence, soap operas that popularise antisocial behaviour and gang culture that creates a sense of family for people who have none.

The question is how to turn the nudges around. A rap song that highlighted the danger of carrying a weapon could be more deterrent than endless knife summits at No10. A health visitor who persuaded working-class mothers to read to their children might have as great an impact on education as a change in the qualifications system. In short, Mr Cameron does not just want to hug a hoody, he wants the hoodies to be persuaded to hug each other. He wants to create a smaller state by reducing demand rather than supply.

This philosophy of “libertarian paternalism” is difficult to get across. It is potentially dangerous for politicians to admit that government is powerless to implement the required changes. Some Shadow Cabinet ministers, notably George Osborne, are worried that the strategy will not resonate if the country is entering economic decline. Others fear the party looking soft - particularly now that Mr Cameron's right-wing cover David Davis is off the front bench. There will need to be some concrete proposals, too. But it may be more honest to admit that there are limitations to the ability of politics to deal with the underlying causes of social problems.

What is extraordinary is that Labour has surrendered the fight against the “broken society” to the Conservatives. When James Bulger was murdered, Tony Blair described the killing as a “hammer blow against the sleeping conscience of society”. It was Mr Brown who devised new Labour's slogan “tough on crime, tough on the causes of crime”. Tackling the underclass should be natural territory for the Left. But ministers seem in denial about the problem - “I don't have any time myself for this talk about... the breakdown of society,” Ed Balls, the Prime Minister's right-hand man, has said. “In most parts of our country there isn't a problem with gun or knife crime.”

It was no coincidence that Mr Cameron chose to make his speech from the Gallowgate estate in Glasgow. Not only is this the area that brought about Iain Duncan Smith's Damascene conversion to social justice; it is also is in the constituency where Gordon Brown might soon have his Garden of Gethsemane moment, kissed on the cheek by hitherto loyal Labour voters. The Tories will not win the Glasgow East by-election, but if they seize the “broken society” territory from Labour they may triumph in the end.

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