Shops looted, cars and buildings burnt out, young adults in hoods on the rampage.

London has woken up to street violence, and the usual narratives have emerged – punish those responsible for the violence because they are "opportunist criminals" and "disgusting thieves". The slightly more intellectually curious might blame the trouble on poor police relations or lack of policing.

My own view is that the police in this country do an impressive job and unjustly carry the consequences of a much wider social dysfunction. Before you take a breath of sarcasm thinking "here she goes, excusing the criminals with some sob story", I want to begin by stating two things. First, violence and looting can never be justified. Second, for those of us working at street level, we're not surprised by these events.

Twitter and Facebook have kept the perverse momentum going, transmitting invitations such as: "Bare shops are gonna get smashed up. So come, get some (free stuff!!!!) F... the feds we will send them back with OUR riot! Dead the ends and colour war for now. So If you see a brother... SALUTE! If you see a fed... SHOOT!"

If this is a war, the enemy, on the face of it, are the "lawless", the defenders are the law-abiding. An absence of morality can easily be found in the rioters and looters. How, we ask, could they attack their own community with such disregard? But the young people would reply "easily", because they feel they don't actually belong to the community. Community, they would say, has nothing to offer them. Instead, for years they have experienced themselves cut adrift from civil society's legitimate structures. Society relies on collaborative behaviour; individuals are held accountable because belonging brings personal benefit. Fear or shame of being alienated keeps most of us pro-social.

Working at street level in London, over a number of years, many of us have been concerned about large groups of young adults creating their own parallel antisocial communities with different rules. The individual is responsible for their own survival because the established community is perceived to provide nothing. Acquisition of goods through violence is justified in neighbourhoods where the notion of dog eat dog pervades and the top dog survives the best. The drug economy facilitates a parallel subculture with the drug dealer producing more fiscally efficient solutions than the social care agencies who are too under-resourced to compete.

The insidious flourishing of anti-establishment attitudes is paradoxically helped by the establishment. It grows when a child is dragged by their mother to social services screaming for help and security guards remove both; or in the shiny academies which, quietly, rid themselves of the most disturbed kids. Walk into the mental hospitals and there is nothing for the patients to do except peel the wallpaper. Go to the youth centre and you will find the staff have locked themselves up in the office because disturbed young men are dominating the space with their violent dogs. Walk on the estate stairwells with your baby in a buggy manoeuvring past the condoms, the needles, into the lift where the best outcome is that you will survive the urine stench and the worst is that you will be raped. The border police arrive at the neighbour's door to grab an "over-stayer" and his kids are screaming. British children with no legal papers have mothers surviving through prostitution and still there's not enough food on the table.

It's not one occasional attack on dignity, it's a repeated humiliation, being continuously dispossessed in a society rich with possession. Young, intelligent citizens of the ghetto seek an explanation for why they are at the receiving end of bleak Britain, condemned to a darkness where their humanity is not even valued enough to be helped. Savagery is a possibility within us all. Some of us have been lucky enough not to have to call upon it for survival; others, exhausted from failure, can justify resorting to it.

Our leaders still speak about how protecting the community is vital. The trouble is, the deal has gone sour. The community has selected who is worthy of help and who is not. In this false moral economy where the poor are described as dysfunctional, the community fails. One dimension of this failure is being acted out in the riots; the lawlessness is, suddenly, there for all to see. Less visible is the perverse insidious violence delivered through legitimate societal structures. Check out the price of failing to care.

I got a call yesterday morning. The kids gave me a run-down of what had happened in Brixton. A street party had been invaded by a group of young men out to grab. A few years ago, the kids who called me would have joined in, because they had nothing to lose. One had been permanently excluded from six schools. When he first arrived at Kids Company he cared so little that he would smash his head into a pane of glass and bite his own flesh off with rage. He'd think nothing of hurting others. After intensive social care and support he walked away when the riots began because he held more value in his membership of a community that has embraced him than a community that demanded his dark side.

It costs money to care. But it also costs money to clear up riots, savagery and antisocial behaviour. I leave it to you to do the financial and moral sums.