Decision theory, as it has grown up in recent years, is a formalization of the problems involved in making optimal choices. In a certain sense — a ve… - Kenneth Arrow

Trust is an important lubricant of a social system. It is extremely efficient; it saves a lot of trouble to have a fair degree of reliance on other people's word. Unfortunately this is not a commodity which can be bought very easily. If you have to buy it, you already have some doubts about what you have bought.

I want to stress that rationality is not a property of the individual alone, although it is usually presented that way. Rather, it gathers not only its force but also its very meaning from the social context in which it is embedded.

Once individuals are acting to carry out a norm and cannot be fully checked, their natural norm of self-interest will come into play. The rules actually acted upon will therefore move away from any norm that might be acceptable on the basis of general principles.