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 i… - Kenneth Arrow

Unfortunately, the word 'learning' is a very general word. It isn't a very specific theory and we can have a lot of learning models, and it's unlikely that any one is going to track. When you talk about learning, you talk about the human mind adapting to conditions, and we haven't nailed that down very well. This is always an objection to the whole idea of bounded rationality. Not that it's wrong, but if it's right, it doesn't actually tell you what to do. Rationality is unique. That isn't really quite true, but at least under many circumstances it is. To say that we're not at the top of a hill gives you a lot of variety as to where you might be. So the problem with bounded rationality is not that it's wrong. On the contrary, I think it's very apt to be correct. It's just that its predictions are a lot more vague than those implied by rationality. At the moment, I don't know what to do about that.

To conclude, I argue that the government should not display risk aversion in its behavior. Hence, the proper procedure is to compute the expected values of benefits and costs, and discount them at a riskless rate, contrary to the view of Hirshleifer (1964, p. 85).
Suppose the future to be unknown; it is known that one of a set of states will prevail, and their probabilities are known (or believed in). A given state means a complete description of all production possibilities, so that all uncertainties are resolved when the state is known. To summarize some earlier discussions (Arrow, 1964b; Deberu, 1959, chap 7; Hrishleifer, 1964, pp. 80-85), we can achieve an optimal allocation if we imagine markets in all possible commodity-options, a commodity-option being an obligation to deliver a fixed amount of a given commodity if, and only if, a given state prevails.

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.