Zeynep Tufecki, in an excellent essay in the MIT Technology Review (which I recommend reading, especially "5. Lessons of the era"):
...Online, we’re connected with our communities, and we seek approval from our like-minded peers. We bond with our team by yelling at the fans of the other one. In sociology terms, we strengthen our feeling of “in-group” belonging by increasing our distance from and tension with the “out-group”—us versus them. Our cognitive universe isn’t an echo chamber, but our social one is...
...This is also how Russian operatives fueled polarization in the United States, posing simultaneously as immigrants and white supremacists, angry Trump supporters and “Bernie bros.” The content of the argument didn’t matter; they were looking to paralyze and polarize rather than convince. Without old-style gatekeepers in the way, their messages could reach anyone, and with digital analytics at their fingertips, they could hone those messages just like any advertiser or political campaign...
...
But we didn’t get where we are simply because of digital technologies. The Russian government may have used online platforms to remotely meddle in US elections, but Russia did not create the conditions of social distrust, weak institutions, and detached elites that made the US vulnerable to that kind of meddling.
...
Russia did not make the US (and its allies) initiate and then terribly mishandle a major war in the Middle East, the after-effects of which—among them the current refugee crisis—are still wreaking havoc, and for which practically nobody has been held responsible. Russia did not create the 2008 financial collapse: that happened through corrupt practices that greatly enriched financial institutions, after which all the culpable parties walked away unscathed, often even richer, while millions of Americans lost their jobs and were unable to replace them with equally good ones.
Russia did not instigate the moves that have reduced Americans’ trust in health authorities, environmental agencies, and other regulators. Russia did not create the revolving door between Congress and the lobbying firms that employ ex-politicians at handsome salaries. Russia did not defund higher education in the United States. Russia did not create the global network of tax havens in which big corporations and the rich can pile up enormous wealth while basic government services get cut.
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If digital connectivity provided the spark, it ignited because the kindling was already everywhere. The way forward is not to cultivate nostalgia for the old-world information gatekeepers or for the idealism of the Arab Spring. It’s to figure out how our institutions, our checks and balances, and our societal safeguards should function in the 21st century—not just for digital technologies but for politics and the economy in general. This responsibility isn’t on Russia, or solely on Facebook or Google or Twitter. It’s on us.