Justice, like liberty and coercion, is a concept which, for the sake of clarity, ought to be confined to the deliberate treatment of men by other men. - Friedrich Hayek

What the planning authority would have to know would not be the mere totals but the distinct, peculiar conditions prevailing in each enterprise which affect the information about values transmitted through market prices but would be completely lost in any statistical information about quantities that might reach the authority from time to time.

My whole concept of economics is based on the idea that we have to explain how prices operate as signals, telling people what they ought to do in particular circumstances. The approach to this problem has been blocked by a cost or labor theory of value, which assumes that prices are determined by the technical conditions of production only. The important question is to explain how the interaction of a great number of people, each possessing only limited knowledge, will bring about an order that could only be achieved by deliberate direction taken by somebody who has the combined knowledge of all these individuals. However, central planning cannot take direct account of particular circumstances of time and place. Additionally, every individual has important bits of information which cannot possibly be conveyed to a central authority in statistical form. In a system in which the knowledge of relevant data is dispersed among millions of agents, prices can act to coordinate the separate actions of different individuals.
Given this context, it is intellectually not satisfactory to attempt to establish causal relations between aggregates or averages in the manner in which the discipline of macroeconomics has attempted to do. Individuals do not make decisions on the basis of partial knowledge of magnitudes such as the total amount of production, or the total quantity of money. Aggregative theorizing leads nowhere.

I don't know what monetarism is. If monetarism just means a good old-fashioned quantity theory, of course it has not failed. If it means the particular version of Milton Friedman, I think it has because he imagines that he can achieve — ascertain — a clear quantity relationship between a measurable quantity of money and the price level. I don't think that is possible. In fact, just about 40 years ago in the opening sentences of my book, Prices and Production, I wrote that it would be a great misfortune if people ever cease to believe in the quantity theory of money. It would be even worse ever to believe it literally. And that's exactly what Milton Friedman does.