The internet is habitually invoked as the prime driver of today's political polarisation: the hermetic echo chambers of Twitter， Facebook and YouTube are increasing division and entrenchment of the sort seen in the Brexit and Trump campaigns.
Users subscribe to feeds， channels and pages offering news that most closely represents their worldview， the story goes， along with misinformation about those who disagree with them， sealing themselves off from an alternative discourse.
Even Barack Obama backed the theory. “The capacity to disseminate misinformation…to paint the opposition in a wildly negative light，” he stated ahead of last year's election， “has accelerated in ways that much more sharply polarise the electorate.”
But there's a problem with this idea. A working paper just published by the US National Bureau of Economic Research has thrown a spanner in the works. It found polarisation had increased most in the over-75s， those least likely to use the internet. So much for the reductive， knee-jerk hypothesis that life online is the key to rising partisanship.
The paper doesn't totally dismiss internet-related effects. It speculates that divisions fuelled online m