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 may radiate out to older people who don't use social media， or indirectly cause polarisation offline， through the selection of political candidates for example or by disrupting traditional media.
There are， of course， other possible explanations. Chief among them is that the politics of nostalgia are increasingly on the march. The Trump campaign was predicated on a rose-tinted view of the past. Now in office， his administration assuages the anxieties of those most wary of progress: the old.
In the UK， where a surprise June general election was announced two days ago， we saw the Brexit campaign capitalise on the same dangerous reverence for how things used to be. A breakdown of the polls confirmed support for Brexit among the over-65s was 60 per cent – the highest of any demographic group. Likewise for Trump: a majority of voters aged 65 and over backed him.
If progress feels alienating and hostile， the fetishised past becomes a cosy place to reside. Its familiarity can be potent. The familiarity principle denotes a psychological and evolutionary phenomenon in which people prefer things they know well. If this manifests in media consumption and voting choice， the digging in of heels becomes more pronounced and the bubble remains sealed，no Facebook required.