Perry Anderson in The New Left Review:

The odious cast of the regimes in place [in North Africa and the Middle East] has persisted unaltered for decades, without triggering mass revolts against them. The timing of the uprisings is not to be explained by their aims. Nor can it plausibly be attributed just to novel channels of communication: the reach of Al-Jazeera, the arrival of Facebook or Twitter have facilitated but could not have founded a new spirit of insurgency. The single spark that started the prairie fire suggests the answer. Everything began with the death in despair of a pauperized vegetable vendor, in a small provincial town in the hinterland of Tunisia. Beneath the commotion now shaking the Arab world have been volcanic social pressures: polarization of incomes, rising food prices, lack of dwellings, massive unemployment of educated—and uneducated—youth, amid a demographic pyramid without parallel in the world. In few other regions is the underlying crisis of society so acute, nor the lack of any credible model of development, capable of integrating new generations, so plain.