Design for a Brain
Ashby described adaptation as a search for a stable state and built the homeostat, a machine that blindly seeks equilibrium after a disturbance.
Why it matters
Adaptiveness here is not programmed in advance but emerges from search, a different mechanism from reinforcing a correct answer.
When a magnet of the homeostat swung too far from the centre, a relay set a stepping switch moving from position to position, each position giving the connections new values; Ashby had taken those values from a table of random numbers. The switching went on until the system came back within its limits. Ashby refused teleological explanation, yet called the behaviour of any stable system goal-seeking: the goal was not built in but followed from stability. This line stayed a minority position next to learning from error, but returned in later work on self-organisation.