Part of the problem is that we all live in echo chambers that tell us what we want to hear. If I believe that grass is blue, then I live in a neighbourhood of p

Part of the problem is that we all live in echo chambers that tell us what we want to hear. If I believe that grass is blue, then I live in a neighbourhood of people that believe grass is blue, and all my friends are thus people who believe grass is blue. I watch news that says grass is blue. My Facebook and Twitter feeds frequently show updates that prove grass is blue, and rarely show anything to the contrary other than to scorn it. All these reasonable people that I love and trust all agree that grass is blue. I'm a reasonable person. So if I meet someone who says grass is not blue, my immediate assumption is that they're a wacko, unreasonable, not to be trusted. It kind of makes total sense. If you don't do this, you start questioning everything, and it's really stressful. You start to become 'that guy', nobody wants to spend time with you because you're so disagreeable, and you prevaricate on every decision. So you simplify the world by limiting your inputs to those that agree with you. For example, "Should I get my child vaccinated? I've read 3 books for, 3 against, asked doctors and health advisors I found on Google, and talked about it on multiple forums. Opinion seems divided. " vs "I know I should get my child vaccinated, because everyone on Hacker News says so." At some point, the answer is to have trusted in-person relationships. As I said, I believe in vaccinations because I know our doctor quite well. I know he's not a quack, and he says vaccinations are a good thing, and so I believe him. Similarly, if I want to get some good beef, I go to our local butcher who knows my name. I trust him not to sell me horsemeat, in a way that I don't trust a big supermarket chain. There's no way for me to guarantee that either the doctor or the butcher are right, but it feels a more certain way than trusting /r/cleverusername on Reddit. How do you sort the wheat from the chaff in a society of billions? I often recollect Aristotle's comment that "it is difficult - perhaps impossible – for a city that is too populous to be well managed". At some point, large societies seem to eat themselves, and the result is a lack of trust in everything around you.