As thousands of policemen prepare to confront a fourth night of rioting and looting in and around London, law enforcement officials and Londoners are scrambling to identify the hooded, masked young people who have been wreaking havoc following the fatal police shooting of a black man named Mark Duggan in Tottenham. The authorities are uploading images of rioters to Flickr as unofficial sites like Catch a Looter, Identify the London Rioters, and London Riots Facial Recognition spring up (there's even a debate about whether the perpetrators should be called "thugs" or "protesters"). Against that backdrop, British commentators and politicians are taking a step back from the minute-by-minute updates to ask three critical questions: Who are the protesters? What do they want? And what explains their behavior? Let's take a look at some of the most prominent theories to answer these questions (several analysts combine several of these points:

  • 'Opportunistic Criminality'  London's acting police commissioner Tim Godwin has characterized the rioting as "pure criminality" capitalizing on the Duggan incident--a sentiment echoed by Prime Minister David Cameron. Lindsay Johns at The Daily Mail argues that there is "no 'legitimate grievance' behind the mass thuggery, only feral mob rule which should have no place in a civilised society."
  • Austerity Measures  Over the weekend, Labour Party MP Chris Williamson suggested that the ruling Conservative Party's austerity measures--a mixture of spending cuts and tax hikes--could in part be to blame for the unrest. "Why is it theTories never take responsibility for the consequences of their party’s disastrous policies," he tweeted.
  • Simmering Problems Among Black Youth  Stafford Scott, who was one of the first to learn of Duggan's death, notes at The Guardian that this weekend, "instead of imploding and turning inward and violent among themselves, as they have been doing for the past decade, the youths exploded." While the "trigger may well have been the killing of Mark Duggan and the insensitive treatment of his family," he adds, the "warning signs" "have long been there for those of us who engage with black youths."
  • Simmering Problems Among All Youth  The Globe and Mail's Doug Saunders claims the events of the past few days aren't "race riots" or "political riots" but rather an explosion of violence from Britain's "futureless youth"--a "'lost generation' of young high-school dropouts" that is "far larger than most other Western countries." He points out that the rioters, who are almost all under 20, hail from mostly poor neighborhoods, "thick with public-housing towers and short on employment opportunities."
  • Hard Economic Times  After dismissing police failures, ethnic tensions, unemployment, and spending cuts as root causes, The Telegraph's Mary Riddell points an accusing finger at a "global economy poised for freefall." London's riots, she explains, "are the proof that a section of young Britain--the stabbers, shooters, looters, chancers and their frightened acolytes--has fallen off the cliff-edge of a crumbling nation."
  • Wealth Disparities  The "policies of the past year may have clarified the division between the entitled and the dispossessed in extreme terms," writes Nina Power at The Guardian, and poverty, high unemployment, and resentment toward the police are all factors. But the bigger pictures is that the riots are taking place in "a country in which the richest 10 percent are now 100 times better off than the poorest" and where, "according to the OECD, social mobility is worse than any other developed country."
  • No Silver-Bullet Explanation  "The media is showing us hour after hour of Outraged Upstanding Citizen all saying the same thing because Upstanding Citizens tend to hit journalists less," British-Egyptian journalist Sarah Carr writes. "There is an echoing void when it comes to the other side of the story, a void that is being filled with image after horrible image and calls for looters to be flogged in public squares and theorising about the legitimate social political grievances that drove them to commit inexcusable acts. Both camps are as bad as each other."