LAW OF REQUISITE VARIETY: the amount of appropriate selection that can be performed is limited by the amount of information available. (2) for appropriate regulation the variety in the regulator must be equal to or greater than the variety in the system being regulated. Or, the greater the variety within a system, the greater its ability to reduce variety in its environment through regulation. Only variety (in the regulator) can destroy variety (in the system being regulated). The law was formulated by Ross Ashby.