For the Arab Spring it was Twitter; for the summer riots in London it was BlackBerry Messenger. This column explores how the latest technology is helping to accelerate ‘information cascades’, where people make decisions based on what they see other people doing – and getting away with.

The mass movement for democracy that has led to the exile of Ben Ali in Tunisia paved the way to a new awakening and raised many hopes in North Africa and the Middle East. This column reports on recent research on the historical experiences of countries that democratised during the “third wave”, to shed some light on the prospects for the future of the Arab region.

Stalin’s mass killings are often viewed as the acts of a deranged dictator. This column suggests that such violence may have been the Soviet leader’s rational attempt to avoid losing power in a revolution.