I was sent a review copy of The Moral Foundation of Economic Behavior, by David C. Rose. Here is what I think is a key passage, which is italicized in the book, on p. 140:

the moral foundation of economic behavior is a norm of unconditional trustworthiness made possible by a preponderance of people possessing an ethic of duty-based moral restraint while not regarding moral advocacy as a moral duty.

I have not been able to follow the argument in the book. This podcast with Russ Roberts gets me closer. Here is what I think Rose is saying.

1. Trust is difficult as groups get large. You cannot completely rely on incentives, reputation, and the like.

2. The best way to obtain trust in a large group is for people in the group to be committed to following moral rules. They won’t cheat, even if they can get away with it, because they think that it is wrong to cheat.

3. People have two potential motives to break rules. One motive is to obtain personal gain. Another motive is to achieve some higher moral objective. Rose wants to say that either motive serves to undermine trust. Therefore, telling someone to focus on higher moral objectives (to “think globally, act locally”) is to encourage that person to break rules, which ultimately will lead to a breakdown in trust.

Again, I do not necessarily get the argument, so do not take my interpretation as gospel. In a way, I see this through the lens of the alleged distinction between act-utilitarianism and rule-utilitarianism. Act-utilitarianism says that you should choose each act in order to make people better off. Rule-utilitarianism says that you should follow rules that, if they were always followed, make people better off. I see Rose as saying that rule-utilitarianism is better, because act-utilitarians cannot be trusted. The act-utilitarian may break his promise for what he sees as perfectly defensible reasons. The rule-utilitarian keeps his promise, regardless. (There is a well-known philosophical problem with the distinction between act-utilitarianism and rule-utilitarianism. You can argue that the former reduces to the latter, or vice-versa. Try to ignore that philosophical problem here, since Rose himself does not rely on that distinction.)

4. Another way to put this is that there are two types of opportunism. There is selfish opportunism, which is breaking the rules to gain for yourself. And there is what I might call utilitarian opportunism, which is breaking the rules in order to achieve what you think is a higher good. About this utilitarian opportunism, Rose would say that:

a) our moral intuition, which is based on based on small-group society, is that utilitarian opportunism is fine. However, this is incorrect.
b) in fact, in a large-scale society, utilitarian opportunism does as much to undermine trust as selfish opportunism.
c) our current educational system and elite culture, rather than urging people to follow rules, urges them to behave morally. It encourages, in both individuals and politicians, utilitarian opportunism.
d) This trend in education and culture threatens to undermine trust.

Again, I am just trying to understand. Had I been the editor of this book, I would have gone back and forth with the author until I was satisfied that the points were made clearly.