It is almost 12 years to the day that a new Conservative party leader proclaimed that a break in Tory tradition and attitudes was needed, and that the country, justice system and political class should understand young hoodie wearers rather than condemn them. David Cameron’s argument, though mocked as “hug a hoodie”, was sound: repeated crackdowns on low-level crime were more harmful than helpful. Criminalising and imprisoning people for minor offences invariably leads not to people being scared straight, but to entrapment in a cycle of crime, with people stigmatised; in greater poverty with fewer job prospects; and exposed to drugs and people who exacerbate the situation.

The past is a different country: back then Tony Blair was still prime minister and the financial crash wasn’t even a speck on the horizon. Similarly, Cameron’s argument that crime should be treated as a problem that involves health and education sectors working together to get to the root of social issues, is out of the window. And on the weekend, Victoria Atkins, a Home Office minister, announced that gang members should expect their families to be evicted if they live in council homes.

Preventing crime and antisocial behaviour involves fixing the society we all live in

The scheme has already been tested in north London, the Home Office says, and will be rolled out nationally. But pursuing these evictions rests on the incorrect assumption that most gang members live in social housing and creates a two-tier system: the poorest have their families made homeless, while the slightly more affluent offenders simply receive a conviction.

Will it work? Unlikely. Preventing people from joining gangs in the first place is a far better bet, as is treating crime as a public health problem. Glasgow used to be the knife crime capital of Britain, but the authorities there stopped treating it as simply a criminal issue and there were no deaths of young people by stabbing in all of Scotland last year.

The Times reported on Monday that 30,000 children might be involved in gangs, and Dame Louise Casey, former director of Cameron’s troubled families programme, claims gangs often recruit damaged and vulnerable children, who are victims themselves, and then force them into criminal behaviour.

If the new policy is rolled out, it will increase the financial, social and psychological damage suffered by all those evicted. Families targeted will lose their child first to the gang and then to prison, and then lose their homes. In which case, either they will be accepted as homeless by the very local authority that has just evicted them and housed in temporary (and expensive) rented accommodation or, more likely, they will be out on their ear. Children will be uprooted from their communities and schools because of the actions of an older brother, losing both a sibling and a home. Finding somewhere new to live is expensive. Many landlords will not let to people on benefits, especially those who have been evicted.

The move just compounds the suffering of innocent family members. Those who simply shrug and blame the parents for failing to control their children need to consider how many well-off parents really know everything about their kids. Children rebel and keep secrets, and if trained professionals with expertise in gangs acknowledge the difficulties in extricating members once they have been tightly and deliberately drawn in, parents have little hope.

But the Tories’ new policy isn’t about ending gang violence, it is simply posturing, a hallmark of the party’s rule since 2010: announce a pointless policy that will cost a lot and provide none of the promised benefits, purely to appear tough. The bedroom tax was similar – it was cruel, cost more to implement than it saved and forced many of the people affected to make expensive disability adjustments to their homes. Many benefit cuts hit single parents hardest and punish children by forcing their families into destitution.

Good policymaking is evidence-based, and preventing crime and antisocial behaviour involves fixing the society we all live in, identifying risk factors and demographic characteristics that make some people more likely to become involved in certain crime, and then preventing those offences taking place as often as possible.

That’s what people who care about stopping crime and protecting victims do. But it seems the Conservatives are more interested in their image and in looking tough to their voters. So instead, the government creates extra victims and sacrifices the life chances of many more people.

• Dawn Foster is a Guardian columnist