The need for ternary mechanism
The two-domain mechanisms of cybernetics, even though they are more sophisticated than the one-domain mechanisms of the mechanical sciences, still do not make provision for the purpose of the human manager, designer or user.
The necessity for such provision arises from the fact that cybernetics is about controlling, managing, governing, and designing—always about systems in which evaluation has to take place—and somewhere the system needs a third domain to contain the determination of what difference is to be regarded as error, and what is not. In even the simplest information system involved in any sort of control or organising, some agent has to define the goal, or determine that some one situation is preferable to another. There is a third domain, which needs to be included in our conception of mechanism, and this third domain is where the imparity in the system resides.
Until now, the imparity in systems has been regarded as a part of the information content, and no distinction of the sort described here has been made.
The two domanial relationships
There is an interesting parallel between the two domanial relationships—that between the first and second, and that between the second and third. It is well-known that the amount of energy involved in information engineering is very small compared to that used in power engineering. Indeed, they are sometimes called 'techniques of weak currents' and 'techniques of strong currents'. In a similar manner, the amount of information required to express imparity is very small. For example, the amount of information transmitted to a television set by its remote commander is very small compared with the amount which needs to be conveyed by the coaxial aerial lead—just as the amount of power carried by the coaxial lead is very small compared with the amount carried by the mains cable of the set.
Why has imparity been ignored?
The fact that the amount of information added to the system by the imparity is so comparatively small may be the main reason why no attention has previously been paid to the importance of the discontinuity between information and imparity. It has always been the case that cybernetic mechanisms have possessed the three components of energy, information, and imparity, but the fact has not been sufficiently appreciated, and our theoretical or practical procedures have not made the ternary structure explicit.
The imparity in a situation or a mechanism needs to be separated out and made a recognised part of the process of cybernetic analysis or design. In other words, cybernetics needs to be concerned with ternary analysis, rather than using theoretical structures which are only designed for dealing with binary analysis—involving information and energy.