With the exception of giving young children an allowance as a way to help them begin to understand how to manage money, the money nexus has little or no place within a healthy family unit. A household run like a business would crush rather than nurture those familial bonds and personal sentiments that are so deeply important to us as human beings. In a world run only by arms-length contracting, market competition, money prices, and the formal “thou-shalt-not” rules that we follow when dealing with strangers, intimate relationships, loving families, and close friendships would not exist. Such a world would be worse than cold; it would be inhuman.

Everyone understands the value of personal relationships governed by love and sentiment. Not only are such relationships part of everyone’s daily lives, we as a species are also evolved to treasure such relationships and to know how to engage in them. Again, parents naturally care for their children; they do not have to be instructed to do so or about how to do so. Likewise, because we humans spent most of our evolutionary history living in small bands of individuals who were known face-to-face to each other—and interacting only relatively rarely with strangers—nearly all of our successful personal connections continue to be with the individuals in our small groups.

The sentiments and emotions that bound members of small groups together and best enabled them to survive and to reproduce became encoded in our genes. These sentiments and emotions, therefore, are inextricably part of who we are. They are part of what it means to be human. And although human society in modern times has grown in size far larger than the small groups in which most of our ancestors lived, these small-group sentiments and emotions remain important “guides” to us in our dealings with our loved ones and friends.

As valuable and agreeable as these small-group sentiments and emotions are, however, they are poorly suited to guide us in our connections with the larger society. We cannot possibly know enough about strangers to be able to interact in their lives as intimately as we interact in the lives of people whom we know personally. Also, we cannot possibly care as deeply about the well- being of strangers as we care about the well-being of our family and friends.

And yet, to flourish in modern society requires our almost-constant interaction with countless strangers. To be productive for everyone involved, these interactions must be based on mutual consent and governed by an ethic of kept promises. But these interactions need not be based on feelings of love, caring, and concern. This fact is fortunate because, as just noted, no one is capable of knowing about and caring about more than a tiny number of the individuals with whom he or she interacts daily.

Being guided in our interactions with millions of strangers by impersonal rules and market forces, our capacity for love and concern for others isn’t over-taxed. Nor are we called upon to learn the details of the lives of these strangers. When you want to buy, say, a new car, you need to know only some information about the quality of the car and its price in comparison with other cars. The only personal information you need to know when deciding whether or not to buy the car is information about yourself. What are your tastes and preferences in automobiles? What is your price range? What financial arrangements to pay for a car work best for you? You do not have to know—and you cannot possibly know—any such personal information about the millions of individuals whose efforts contributed to the production of the car.

The rules for interacting with strangers overlap with, but are much “thinner” than, the rules for interacting with people whom we know personally. Treat strangers with respect and do not presume that you are a better judge than they are of what is best for them; do not steal from strangers; do not cheat them; initiate no violence against them; keep your promises to them; respect their property rights. To follow these rules requires no personal knowledge of strangers. When people follow these impersonal rules when dealing with strangers in the economy, “arms-length” exchange and contracting occur. These exchanges and contracts give rise to market prices. These prices, in turn, guide each of us to interact productively—as both consumers and as producers—with the increasingly large numbers of strangers who make our modern lives possible.

The success and sustainability of modern society, therefore, requires that each of us be guided by our small-group norms when interacting with people we know personally, yet also to put those norms aside when interacting with strangers.

Switching back and forth between these two sets of very different norms is difficult, especially because we are genetically hard-wired to follow small-group norms. When we see on television or in Internet clips the faces of strangers who are suffering job losses or some other economic misfortune, our small-group norms trigger within us sympathies for these strangers (especially if they share our political nationality). So when government officials promise