I don't agree with Charles Green's account of trust in markets. It doesn't fit what businesses do, and it doesn't fit what economists write about. Trust is not about ethics; it's about relying on other people to deliver outcomes. And more than anything else, it's about distributing the social cost of delivering reliable outcomes.

One of the most common things in markets is that people will happily a higher price for a better quality product. Apple makes seriously high margins on iPhones, not because they have better ethics than their competitors (if only!) but because they have consistently high build quality and their products are a pleasure to use. When I say I trust Apple, I'm saying that I can rely on all the things people have said about their iPhones to be true about my iPhone.

Another very common occurrence is that businesses will extend credit to regular customers, but strangers pay cash up front. Customers seldom cry "sucker!" and refuse to pay, because a credit account is a valuable thing to have. Strangers pay cash because we trust the currency. No need to do a background check on everyone who buys from me, as long as I can recognise a fake twenty, and rely on my neighbours to spread the word if someone's in town speading fake twenties.

One of the great things about markets is they allow us to do deals with strangers, and be quits at the end of the transaction. As for the good karma, that's something we can pay forward; we don't have to pay it back.