Defining the subject-matter
The phrase "purpose and directiveness", covers not only gubernation (which includes government, management, and control) but also designation (including design, adaptation, and evolution). This exactly covers the central concerns of cybernetics, as they were originally conceived by its founders (Rosenblueth et al, 1943).
To clarify precisely what subject-matter is covered by these terms, three points need to be made:
1. Governing and designing are the analogues of each other
All the cybernetically interesting things that can be said about governing can also be said about designing. So the fundamental processes are not only gubernation (which is more usually thought of as the main subject-matter of cybernetics) but also designation.
2. Governing and designing are the inverse of each other
A well-designed system needs little management, and the less well-designed it is, the more management it needs. The worse the design of the system, the more intervention will be required.
The amount of management that a system requires, is in inverse proportion to the success of its original design. This is the Reciprocal Law of Gubernation versus Designation.
The proportion of time occupied by intervention we call the intervention ratio. That is to say, a well-designed system has a low intervention ratio, and a badly-designed system needs a high intervention ratio.
3. Gubernation and designation can be externally imposed
Cybernetics covers, not only situations where systems exhibit some form of directiveness themselves, but also those where the gubernation or the designation is imposed on the systems from outside, by an external controller or designer, who has a purpose in doing so.
The subject-matter of cybernetics therefore covers, not only things which are governed by some purposive agent, but also those which are self-governing, or governoid. Similarly, a system can be designed by an external designer, or it can appear to be designed, but in fact have evolved itself, that is, be designoid.
The quadrants of cybernetics
Of the four quadrants so defined, people often think of cybernetics as covering only that of governoid systems. Cybernetics often suffers from being conceptually restricted in this way, but it should properly be thought of as covering all four quadrants of this diagram.