I would also trust a mutual friend over a complete stranger. But that's not the point of the observation: the observation is that "trust" isn't a boolean, but an umbrella term for a wide range of policies that we apply to different principals.

Or in other words: transitive trust is a thing, but it's of a different color than "trust." Attempts to gloss over this in web-of-trust designs have historically not gone well.

So you can trust friend of a friend only after awaiting him (with apologies to https://journal.stuffwithstuff.com/2015/02/01/what-color-is-...)?

100% agree about the difference in meaning between the two uses of “trust”. To be frank I responded after only skimming over your comment, and should have read a bit more closely. FWIW, I think there’s a way to unify those two realms: if you model boolean trust in terms of a random variable and sum over the transitive web à la binomial distribution.