You should find this econtalk podcast helpful. They are talking about David Rose's book Moral Foundations of Economic Behavior and do a better job than most of defining what trust is and what it requires. And why it is important.
Thank you, though I wish there'd been more about what bright-line moral rules are a good enough deal for individuals that compliance makes sense, not to mention what can happen when a bright line system has good and bad parts, and people start to notice that.
As a result of going to that site, I listened to Nassim Taleb on anti-fragility (systems which become stronger when challenged)-- it's at least as interesting.
One of the more important types of decisions is deciding who to trust and about what, but I don't think I've seen any discussion here about rational methods in that area.
Any suggestions?