ROSS ASHBY - The Cybernetic Brain - page 159

ity. In Design for a Brain , Ashby gets his third estimate by thinking about the
situation in which any rotor that comes up A is left alone and the other rotors
are spun again, and so on until there are no Bs left. Alexander, in contrast,
considers the situation in which the one hundred lights fall into subsystems of
ten lights each. These subsystems are assumed to be largely independent of
one another but densely connected internally. In this case, the time to dark-
ness of the whole system will be of the order of the time for any one subsystem
to go dark, namely 2 10 seconds, or about a quarter of an hour—quite a reason-
able number.
We recognize this line of thought from Design , but the advantage of putting
it this way is that it sets up Alexander's own solution to the problem of design.
Our contemporary problems in architecture stem from the fact that the vari-
ables we tinker with are not sufficiently independent of one another, so that
tinkering with any one of them sets up problems elsewhere, like the lit light-
bulbs turning on the others. And what we should do, therefore, is to “diagonal-
ize” (my word) the variables—we should find some new design variables such
that design problems only bear upon subsets of them that are loosely coupled
to others, like the subsystems of ten lights in the example. That way, we can
get to grips with our problems in a finite time and our buildings will reach an
adapted state: just as in unselfconscious buildings, the internal components
will fit together in all sorts of ways, and whole buildings will mesh with their
environments and inhabitants. And this is indeed the path that Alexander fol-
lows in the later chapters of Notes on the Synthesis of Form , where he proposes
empirical methods and mathematical techniques for finding appropriate sets
of design variables. One can also, though I will not go into this, see this reason-
ing as the key to his later work on pattern languages: the enduring patterns
that Alexander came to focus on there refer to recurring design problems and
solutions that can be considered in relative isolation from others and thus sug-
gest a realistically piecemeal approach to designing adapted buildings, neigh-
borhoods, cities, conurbations, or whatever (Alexander et al. 1977).
What can we take from this discussion? First, evidently, it is a nice example
of the consequentiality of Ashby's work beyond the immediate community of
cyberneticians. Second, it is another example of the undisciplined quality
of the transmission of cybernetics through semipopular topics like Design
for a Brain . I know of no evidence of contact between Alexander and Ashby
or other cyberneticians; it is reasonable to assume that Alexander simply
read Design and saw what he could do with it, in much the same way as both
Rodney Brooks and William Burroughs read Grey Walter. Along with this, we
have another illustration of the protean quality of cybernetics. Ashby thought