I think that HN readers trend rationalist and see the problem as one of presenting evidence. I respectfully disagree and present a different perspective, one which premises that objectivity is futile and that information is social/tribal.
There is truth and then there is information. I think that people can know only information — projections of truth we think to be truthful. Information must be stored as memory and thereby is rendered organic and messy.
I argue that information is socially constructed. Given the overwhelming complexity of the world, individuals evaluate the trustworthiness of information by how much they trust its transmitter and how people in their network — who collectively form their realities — also receive that information. There is scarcely enough time or resources for individuals to independently evaluate information (in a non-social way for truthiness). Observe for ourselves: how much do we accept as information just because someone we and our friends/family/colleagues trust says it?
In short, (I think that) we believe what others believe. The cost of evaluating information is too high, and so too is the social cost of believing something that is contrary to the beliefs of those others who constitute our immediate realities (the ones we directly experience day to day).
The answer in a democratic society that aims to have a free press? I think that at an abstract level the answer will have something to do with shortening the diameter of our society-level social network and more densely connecting distant subgraphs — such that different social realities can be bridged and the Overton window can be narrowed around the mean.
One merge-tribes implementation: Institutions that socialise people at a national or state-level and cross social classes, like a year of mandatory national civil service around the country. As we go through life, we progress through a series of institutions that socialise us at increasingly wider levels: family, grade school (hyperlocal), maybe religious group, middle school (local), high school (local), then university for some (international or national but upper middle-class if prestigious; otherwise regional). The EU’s Erasmus Programme brings EU students to study in other EU countries: individual networks that otherwise would never connect, get connected — and at a collective level the Programme contributes toward a pan-European identity. But in the US and the EU there are lack of institutions that socialise the masses both at a national/union level and across class. I expect that people will balk at the idea of a compulsory program in a “free” society, but I think that it is more productive for people to think about what a healthy society should ask of each members so that it can sustain a healthy abundance of freedom.
Another idea: Facebook and other online social networks creating intimate channels — not mass channels that inevitably devolve into shouting and chanting — that foster more cross-societal interaction and awareness. Though I think this is a lot weaker than an “IRL” solution.
I find our modern epistemic crisis very interesting and welcome emails to discuss.