People adopt hard-to-verify beliefs more readily when those professing them visibly bear costs that would be irrational if the belief were insincere.
Henrich's 2009 account addresses a problem in cultural learning: a claim that cannot be checked is worth little from a speaker with nothing at stake. Acting on the belief at real cost is the evidence. It explains why fasting, tithing, martyrdom and personal risk transmit conviction far better than assertion does.
In practice
- A chief executive who takes the pay cut before announcing the freeze is believed; the one who announces it from the same salary is not.
- A parent who will not cross a picket line teaches more about solidarity than a decade of saying so.