Property systems are in general not completely self-enforcing. They depend for their definition upon a constellation of legal procedures, both civil … - Kenneth Arrow

Government economic policy, like almost any realistic decision problem, has two fundamental characteristics: it is sequential and it is uncertain.

If the markets for durable goods are peculiarly sensitive to price anticipations, while those for perishable goods are more sensitive to current prices, then there is a little more scope for explaining economic fluctuations.

If the state of information (the set of signals received) is given and constant, then optimal choice is a problem of decision making under a given uncertainty, a situation that has been the subject of considerable analysis in the last thirty years. The problems of the economics of information proper arise when the probability distribution of states of the world is a variable. In the language adopted here, the signals received can vary. The existence of signals creates two important possibilities for the improvement of decision making. The first is taking advantage of the existence of signals. If the individual knows that a signal will be received before the decision has to be made, his optimal choice should be a function of the signal. We can think, alternatively but equivalently, of making the decision after the receipt of the signal and basing it on the probability distributions of consequences conditional on the signal, or of making the decision in advance for all possible values of the signal.