Social theories are also social facts. Whatever explanatory value the “Marxist” or “conservative” models may have, they surely cannot be regarded as … - Kenneth Arrow

The problem of measuring utility has frequently been compared with the problem of measuring temperature. This comparison is very apt. Operationally, the temperature of a body is the volume of a unit mass of a perfect gas placed in contact with it (provided the mass of the gas is small compared with the mass of the body). Why, it might be asked, was not the logarithm of the volume or perhaps the cube root of the volume of the gas used instead? The reason is simply that the general gas equation assumes a particularly simple form when temperature is defined in the way indicated. But there is no deeper significance.

The need for coordination has two basic causes: the various members (e.g., production units) are competing for a common pool of resources, financial and material; and different decisions complement or substitute for each other. For both reasons, the effectiveness of decisions made by one participant is influenced by the decisions of another. With limitations on the flow of information, the decisions themselves cannot be coordinated. That would require transferring all the information available, precisely what is to be avoided. It has been emphasized earlier that when information will be available, the individual should choose a decision function, a policy or strategy that determines what his actual decision should be for each possible signal he receives. Hence, ideally, in an organization there should be prior agreement on decision functions or strategies for all participants.

Despite the favorable properties of the price system, I am no unrestrained admirer of it. Some of its limits in the urban context will be stressed below. It is not possible, however, to understand the city as an economic problem without first understanding the virtues of the free market system in performing its role of allocating resources.