Very concrete examples of persistent nonrational social norms can be found in consumer science.
For years, we received medical advice on fats and salt that had little scientific backing. Yesterday, an article appeared showing Medical benefits of dental floss unproven.
I had had my suspicions about the fat and salt though I did lean toward reducing intake, but the lack of evidence for dental floss surprised me.
Imagine tens of thousands of hygienists and dentists repeating the advice to floss over all those years. Dental floss is a multi-billion dollar industry.
I don’t blame hygienists or dentists. They were faithfully doing what they were taught—transmitting a social norm that seemed to be science-based (but was not).
That’s how societies hold together. Common beliefs and norms are typically transmitted by authority figures at the top. After the authority figures, come parents, news media, teachers, etc. in a long chain of transmission. Each in turn repeats what they have learned.
Could be about dental floss or it could be about keeping the sun in the sky by cutting out people’s hearts.
You can see something similar at an individual level. Much of human psychology is based on habits transmitted internally from one day to the next in long chains that sometimes can be traced back to infancy.
Much of what we think and feel is nothing more than habit transmitted faithfully from one moment to the next.
Psychological habits, like social conformity, work according to rules that we can understand in terms of reason but that often are not themselves reasonable.