The practical problem is to bring production potential into alignment with a pattern of social need revealed by a combination of democratic political decisions (as in the case of, say, the appropriate level of public health service provision) and aggregate consumer purchases. Given a reasonable data-collection system reporting on the rates at which consumer goods are selling, and assuming a pricing system based on labour values (Cockshott and Cottrell, 1993), deriving a target net-output vector demands no special telepathic powers on the part of the planning system. It is perhaps harder to gather the information about production possibilities. It is in this practical context that Hayek's discussion of centralised versus decentralised control systems must be placed.