The social elevator is broken. This notion, recently popularised by French writer Aziz Senni, comes as close as any rational analysis can to explaining the thinking of the rioters who have turned France's outer suburbs into scenes of anarchy over the past week.

What France has seen is, in part at least, a revolt of a marginalised section of society - heavily, but not exclusively Muslim - cut off from economic opportunity by the policies and attitudes of the establishment. Any strategy for bringing social peace must include demolishing the barriers that have kept these latter-day sans culottes at the margins of the French economy.