“BUILDING SOCIAL capital will not be easy, but it is the key to making democracy work,” wrote Robert Putnam, an American political scientist, in 1993. He found that places where people trust and collaborate with others beyond their immediate social circles fared unusually well on a wide range of political and economic measures. His argument has gained traction as satisfaction with democracy has sunk to record lows globally. But Mr Putnam might strike a more optimistic note in his lecture at the Royal Society of Arts on March 24th. He is introducing research by Meta, the social-media giant that operates Facebook, showing that Britons are more “economically connected” than Americans—a measure of social capital.