Studies of intelligent systems, natural or artificial, tend to focus on dynamic models or symbolic models, rarely both, finding it difficult to integrate the two. But here we are asking the synthetic question — How does a cybernetic system come to develop semiotic systems, mediated both internally and externally, capable of bearing the information it needs to survive and achieve its other objectives?
With that in mind, let’s return to Ashby’s text, picking up the argument where he underscores his thesis up to this point and continuing from there.
Regulation In Biological Systems
10/6.[concl.] In general, then, an essential feature of the good regulator is that it blocks the flow of variety from disturbances to essential variables.
10/7. The blocking may take place in a variety of ways, which prove, however, on closer examination to be fundamentally the same. Two extreme forms will illustrate the range.
One way of blocking the flow (from the source of disturbance to the essential variable is to interpose something that acts as a simple passive block to the disturbances. Such is the tortoise’s shell, which reduces a variety of impacts, blows, bites, etc. to a negligible disturbance of the sensitive tissues within. In the same class are the tree’s bark, the seal’s coat of blubber, and the human skull.
At the other extreme from this static defence is the defence by skilled counter-action — the defence that gets information about the disturbance to come, prepares for its arrival, and then meets the disturbance, which may be complex and mobile, with a defence that is equally complex and mobile. This is the defence of the fencer, in some deadly duel, who wears no armour and who trusts to his skill in parrying. This is the defence used mostly by the higher organisms, who have developed a nervous system precisely for the carrying out of this method.
- Ashby, W.R. (1956), An Introduction to Cybernetics, Chapman and Hall, London, UK. Republished by Methuen and Company, London, UK, 1964. Online.