ROSS ASHBY - The Cybernetic Brain - page 128

head-on. And in this passage, he takes this discovery to what might be its logi-
cal conclusion. If, beyond a certain degree of complexity, the performance of
a machine could not be predicted from a knowledge of its elementary parts, as
proved to be the case with DAMS, then one would have to abandon the mod-
ern engineering paradigm of knowledge-based design in favor of evolutionary
tinkering—messing around with the configuration of DAMS and retaining
any steps in the desired direction. 32 The scientific detour away from and then
back to performance fails for systems like these.
The blueprint attitude evidently goes with the modern ontological stance
that presumes a knowable and cognitively disposable world, and Ashby's
thoughts here on going beyond design in a world of mechanisms evolving
quasi-organically once more make the point that ontology makes a difference,
now at the level of engineering method. We can come back to this point in
later chapters.
Ashby never reached the shores of Lake Chad, but one feature of DAMS's
performance did become important to his thinking: a behavior called “habitua-
tion.” In his only published discussion of DAMS, after a discussion of DAMS it-
self, Ashby turns to a theoretical argument, soon to appear in Design for a Brain ,
that he claims is generally applicable to any “self-switching network, cortex or
D. A. M. S. or other, . . . no matter in what random pattern the parts are joined
together and no matter in what state its 'memories' have been left by previous
activities.” This argument has two parts: first, that a system like DAMS will
naturally split itself up into subsystems that “ tend to be many and small rather
than few and large ”; and second, that such a system becomes habituated to a re-
peated stimulus, inamsuch as “it will tend to set its switches so that it is less, rather
than more, disturbed by it .” Then Ashby returns to his machines, noting first
that the latter effect had been demonstrated on the homeostat, where, indeed,
it is true almost by definition: the first application of any stimulus was liable
to provoke a large response—the tripping of the unselectors—while once the
homeostat had found an equilibrium configuration, its response to the same
stimulus would be small: a damped oscillation returning to the equilibrium
state. By 1951, Ashby could also remark that this property “is already showing
on the partly-constructed D. A. M. S.” (1951, 4, 5; Ashby's italics).
Ashby regarded habituation in his machines as support for his general ap-
proach to the brain. “In the cerebral cortex this phenomenon [of diminishing
response to a stimulus] has long been known as 'habituation.' It is in fact not
restricted to the cerebral cortex but can be observed in every tissue that is ca-