A generation ago, autocrats could still hope to maintain control of information within their countries and to limit the ability of citizens to communicate with one another and the outside world. Today, people carry gadgetry that allows them to send ideas hurtling across borders, to connect with one another as never before.

Satellite television, mobile phones with cameras, Facebook, YouTube and Twitter have empowered the individual. Recent headlines remind us that the state is developing new tools of its own. But the decision by former US Central Intelligence Agency employee Edward Snowden to expose the National Security Agency’s data dragnets demonstrates that state-sponsored surveillance may prove as difficult a secret to keep as any other in an open society.

A battle has now been joined. China still uses its “great firewall”, a system designed to monitor and filter internet traffic, but even the hardest of hardliners knows that China’s online conversation is expanding much faster than Beijing’s ability to manage it. Russian, Saudi and Iranian officials try to censor but they cannot return to the day when most messages with political content were broadcast from a regime-run radio or TV tower.