Trust (confident dependence upon the fulfillment of promises) and honor (the quality of being trustworthy) form the difference between barbarism and civilization. Without them, humans inevitably devolve into backstabbing.
If I say that I’m going to do something, it’s important than I then follow through with my promise. Your level of trust in me is how confident you are that I’m going to deliver when I give you my word. The more trustworthy I seem, the more likely you are to trust me—to depend on me following through, acting as if it’s all but certain to happen.
So trust is Bayesian, built up with experience: the more I have previously done what I said, the more likely you are to trust me with higher stakes. And vice versa! If I’m consistently flaky, you’ll be skeptical of taking risk by believing my word.
If two people have trusted each other for years and over dozens of interactions, without issue, they can depend on each other without hesitation: proven trust is the foundation of strong relationships. The same goes for organizations: I’ve received my package every time I ordered something on Amazon, so I don’t worry at all about clicking “order,” as I might for a one-off order from some random other website.
The value of longstanding trust is made most clear when it’s lacking. Whenever I ask a stranger to do something for me, I’m wary—who knows if they’ll follow through? What if this new website just takes my money the first time and runs, never sending the thing I bought? When I don’t have a prior relationship with someone, there is uncertainty and risk involved in dealing with them, so it’s extra costly! I have to spend extra time and energy planning for the case where they don’t follow through, double-checking that they’re proceeding on their task, just worrying in the background in general.
Communities are valuable because they enable trust formation: their members have a reputation with each other, a shared sense of their trustworthiness. If you screw over a member of your tight-knit church, everyone else will hear about it, so you stand to lose many of your other relationships! Because betrayal has such a high cost within communities, members can trust each other more than strangers, even without a prior relationship. Are you really going to risk losing the trust of our entire community to get one up on me in a random transaction?
Many million- and billion-dollar deals in the tight-knit worlds of finance and business are made with a handshake, and only formalized later; this is why. Sure, if conditions change, someone who regrets their decision could back out: but word of this dishonorable act would spread to everyone they deal with regularly, nobody would trust them anymore, and their career would be over. It’s hardly ever worth sacrificing your entire livelihood to make a single quick buck.
Nevertheless, some people are untrustworthy, and some people do betray each other at will. But as they do this, they inevitably drive away any trusting people around them, and are left in a cesspool of other reprobates. Such people cannot trust each other—and they know it. So their days and efforts are spent plotting to backstab others, and trying to avoid being taken for a ride themselves; this arms race of guilery ensures that anyone who focuses on anything but such cunning is swiftly ruined. With their entire focus on these zero-sum games, there is no room for productivity, for improvement, for development; rather, what dregs of value exist ceaselessly change hands until they are consumed or destroyed.
When promises are kept, minds are freed from endless scheming, and can move on to greater things: to learning, to relaxation, to mastery, to wisdom. It is trusting minds that have discovered and made abundant the fruits that humanity enjoys.