A decade ago, Cass Sunstein, an American legal scholar, co-authored a book, Nudge, with the economist Richard Thaler. In it, they argued that subtle social cues — nudges — can shape the behaviour of populations. The idea proved so persuasive that it influenced White House policy, and Sunstein and Thaler rose to prominence. 

Now Sunstein has published another book, #Republic, which describes how social media shapes politics and journalism. So far, it has not received as much attention as Nudge. This is a pity: the ideas in #Republic are arguably more important — and more pressing.

These days, many voters seem furious with both journalists and social media. In this column last week, for example, I wrote about the tribalisation of the media. This has sparked more online reader comments than almost anything else I have written — and most of them are angry.