"Postmodernism" started it all. That "liberating" doctrine initiated the quest for the exaltation of the self. I'm entitled to my own opinion. I will not be a conformist. Look how passionate I am! Doing things out of anger (er, I mean, out of "passion") started being more important than accepting objective reality, because no one wanted to be the dull robot who followed the rules. Individualism --uniqueness-- was cool.
There used to be a time when we accepted that we couldn't assimilate all the information available around us (because, logically, we couldn't experience it all for ourselves), so we outsourced that knowledge to a credible source. We took it from them, at face value. We trusted.
But oh, no. Postmodernist gave us agency. We now know better. Our guts tell us so.
With time and the inflated prominence of one's (and most importantly, one's opinions) worth came the disdain for the unwitnessed fact, and the privileging of the individual's point of view over the point of view of the better-informed, better-equipped professional fact-deliverer. Only what's experienced can be believed. Never mind that there's no way our experiences can objectively inform us of reality.
The consequence was a detachment from the authorities that were supposed to know better than us. A rebellion of belief (of sorts); the untethering of monolithic collective discourse. That social contract broke down. Why should we trust a questioned, sold-out institution with veritable pernicious hidden interests that does not necessarily has my interest in mind?
Welcome to the disruption of truth.
The internet (for better and worse) democratized the voice of anyone willing to type a point of view (yes, yours truly included), destroying the barriers of entry that erstwhile well-recognized institutions enjoyed. Algorithmic-driven social media simply amplified the intensity of what we had to say. The seeds of distrust were planted, and now they've blossomed --with good reason-- into the obliteration of the reputation of the much derided "mainstream media." What is CNN after all, if not the US version of RT.com?
We don't trust anymore.
The societal glue that kept us from buying a gun because we trusted that dystopian marauders wouldn't kill us at their whim came unstuck. We don't trust that the government will spend our money wisely, or that they won't spy on us. We don't trust that your currently crappy public school will get better only if you send your middle class kids there. We don't trust that your cragslist-sourced plumber won't show up with a chainsaw to decapitate you.
And as this social disengagement (social distrust) touches alarming levels, a counter cyclical trend arises: the hyper-engagement in the tribe. After all, we're genetically in need of connection. Loneliness kills. Allegiances are being withdrawn from the Nation and re-pledged towards a more narrowly defined niche --and in some instances, to a Nation that ceased to exist a long time ago.
Social capital is depleted at the National level, but it continues to build up among tribes, and that is a very dangerous place to be.