A recent example: evidence that puberty blockers are safe and effective was overestimated because institutions were circularly citing each other.

9. Post-journalism

The press lost its monopoly on news when the internet democratised info. To save its business model, it pivoted from journalism into tribalism. The new role of the press is not to inform its readers but to confirm what they already believe.

“The new role of the press is not to inform its readers but to confirm what they already believe.”

10. Roseto Effect

Many long-term studies, including the 50-year Roseto study and the 85-year Harvard Study of Adult Development, found that having close-knit relationships is as important for longevity as diet, sleep and exercise, yet it’s often neglected by fitness gurus. If you want to live, love.

11. Hitchens’s Razor

“What can be asserted without evidence can be dismissed without evidence.” ― Christopher Hitchens. If you make a claim, it’s up to you to prove it, not to me to disprove it.

12. The Liking Gap

Multiple studies have found that people consistently underestimate how much a conversation partner likes them and enjoys their company. So don’t be shy, you’re probably cooler than you think.

13. Boomerang Effect

Deny someone something, and they’ll want it even more, out of defiance. If you want your child to eat broccoli, tell them they’re not big enough to eat broccoli. This also helps to explain why censorship often backfires (the Streisand Effect).

14. Anchored-to-your-own-history bias

“Your personal experiences make up maybe 0.00000001% of what’s happened in the world but maybe 80% of how you think the world works.” — Morgan Housel. Boomers and Generation X had wildly different experiences of how the economy works, and this gave them different dispositions, world views, and political preferences.

15. Common Knowledge Effect

Groups are meant to be better decision-makers than individuals, because they combine many perspectives. But in practice, a group doesn’t base its decisions on the info specific to each member, but only on the info common to them all. This casts doubt on the idea that “two heads are better than one”, and helps explain why, despite popular wisdom, diversity generally does not make teams better.

16. Gibson’s Law

“For every PhD there is an equal and opposite PhD.” Both sides in a court case or policy debate will have support from experts, no matter how crazy the position, because education doesn’t make someone right, it often just makes them more skilled at being wrong.

17. Cached Thoughts

Most of your beliefs were formed earlier in your life, when you were more naive. You continue to believe them only because you’ve never reconsidered them. When you’re about to offer an opinion, consider when you formed it, and ask: is it really your belief, or that of your younger self?

And one final thing: as usual, don’t mistake these rules of thumb for laws of nature, as that would be a fallacy called Secundum Quid.