Violence is the symptom of the breakdown of a more civilised social discourse: a social dialogue that is premised on both the freedom to speak and a commitment to listen. A conversation that is the bedrock of a non-violent society, one that contains difference, politics and discord. Murder – like war –  disrupts that social contract. To ensure that this rupture is not irrevocable, we have to find a way to understand what happened and why in order to find a way to pick up the broken threads of meaning in the aftermath of violence in order to stitch together a shared social fabric.

These were the thoughts on South Africa that I presented at Cambridge University. Then on Wednesday, in the serenely ancient rooms that I was staying in at St John’s College, I watched a man being butchered on a drab Woolwich street. This unspeakable killing took place in full view of Londoners going about their afternoon business and the pictures spread – as such images do – like a malignant and infinitely replicable virus over the internet. You have all seen them by now: A man with blood-soaked hands, holding kitchen knives, a leering grimace on his face demanding that passersby take his picture.

When I first watched the clip – unedited, unexplained, unfiltered as news is on social media these days – it looked like the trailer for a particularly low-budget slasher movie. Or a videogame. Or a particularly gruesome piece of news coverage of a civil war in the far away ‘elsewhere’ that is television and is certainly not Britain. However, what made this killing – vicious, bloody and intimate as only a stabbing death can be – shocking is not the death, not the pictures, but the fact that it had happened in the heart of London. The men who hacked Drummer Lee Rigby to death told any phone-camera that was pointed at them – and there were many – that they had killed this serving soldier to avenge the deaths of Muslims in Afghanistan and Iraq. Very quickly what had looked like a particularly insane street murder was being described, packaged and cordoned off as a terrorist attack. The news reports sighed a collective breath of relief at having found so quick an explanation, so easy an enemy and opinion pieces were filled with talk of fundamentalism, Jihad and Islamic extremism. I was struck by the fact that, despite the naked brutality of the murder and the clarity of what the killers said in the aftermath, there seemed to be a refusal of any sense or context to this killing in political statements (promises of a crackdown) and in the news reports (the madness of terrorism, the insularity of a besieged and infiltrated island).

The fractures in British society seem to me to be deeper and more painful every time I visit, but this murder and the knee-jerk Islamophobia that followed in its wake, stirred up by the far right and the tabloids, meant that London was on edge when I returned from the muffled privilege of Cambridge. There was wariness in people’s eyes on the subway, that quick unsettling flick of the eyes for the woman in a hijab, another for the dark-skinned Muslim men who get on at Oxford circus and speak quietly to each other in south London accents. Those looks that reminds people they are not quite part of the body politic.

Alongside the enormous floral tribute that is customary at the sites of British murders, there was also an outpouring of shock, anger and sorrow at Lee Rigby’s murder. Many Muslim leaders, communities and the families of the killers publicly demonstrated and apologised against this gruesome killing. This is understandable – we are all sorry – but the people saying sorry were not the people who killed the soldier. And their apologies, their anguish, their anger, seemed to do little to undo the social disaffection that simmers in England and throughout Europe these days.

And then there was the vandalising of mosques and a number of assaults on Muslims in the streets. I wondered at the apparent conflation of all British Muslims with this particular crime. It indicates a deepening divide between Muslim and non-Muslim British people, a divide into which more young men like the two now charged with the murder will fall, lured by the radical preachers and their unbending certainties.

The British social commentator, Terry Eagleton, wrote in an astute piece in the Guardian that the murder of Drummer Lee Rigby must be understood within the context of ‘western foreign policy’ rather than dismissed as irrational. He argues that politicians and commentators who refuse to look at this murder in the context of the ongoing brutality in the far-flung countries where British and US troops are waging the viciously stalemated ‘War on Terror’, a war that is without boundaries and one in which a great number of innocent people have been killed, are in a dangerous form of denial.

This – western foreign policy – is the surface meaning, the obvious explanation and, on that conscious, political level, there is much truth in it. A truth that needs to be addressed urgently. The sustained but displaced violence of remote wars is making its presence felt more and more in Britain and the United States. These wars – part of the amorphous and often amoral ‘War on Terror’ seem to be circling closer.

However, this does not explain entirely why two young men from South London were willing to knife a man in full view on a crowded street.

What was it that made them embrace this cult of killing for a cause, what was the appeal of a rigid fundamentalism that demands such spectacular sacrifice in order to satisfy the brotherhood of which they must imagine themselves to be a part?

The killing in Woolwich was an orchestrated performance; it is not by chance that it looked like a movie, like a videogame, like the other brutal killings of innocent people that convulse the headlines with such grim regularity. There seems to be a profound and nihilistic lure for increasing numbers of disaffected young men in the violence and in its cinematic display.

There is religion of a sorts involved, of course, a viciously misogynistic, nihilistic and intolerant form of fundamentalist Islam, but I suspect that the origin of this violent and community-defying behaviour lies elsewhere. Somewhere in the heart, in the family, in anxious, overcrowded societies that have no idea how to contain and channel the energy and anger of their young men.

These two young Londoners with their kitchen knives bring to mind the murderous Boston brothers who set off the pressure cooker bombs at the Boston Marathon. Although ideologically they are not aligned, the desire for a Tarantino-esque spectacle of choreographed violence, they are akin to the young men who massacred children at Sandy Hook Primary, at Columbine and too many schools to count across the United States.

They reminded me, too, of the thousands of young men seduced into the rigid gangs that control and order so many poor South African streets. Attracted by the same chimera of a hyper-masculine brotherhood, of belonging, of order and status that a gang offers. These killers are young, male, enraged. The language they speak is violence. We must learn it fast if we want to hold open that reciprocal space of conversation where languages other than violence can be spoken. DM

This article first appeared in the Sunday Times 2 June 2013. Margie Orford’s latest book, Water Music, will be published by Jonathan Ball in July.