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I want just to sketch out his approach to these topics. I begin with what I take
to be right about his epistemology and then turn to critique.
How can we characterize Ashby's vision of knowledge? First, it was a defla-
tionary and pragmatic one. Ashby insisted that “knowledge is finite” (Ashby
1963, 56). It never exceeds the amount of information on which it rests,
which is itself finite, the product of a finite amount of work. It is therefore a
mistake to imagine that our knowledge ever attains the status of a truth that
transcends its origins—that it achieves an unshakeable correspondence to
its object, as I would put it. According to Ashby, this observation ruled out
of court most of the contemporary philosophical discourse on topics like
induction that has come down to us from the Greeks. And, having discarded
truth as the key topic for epistemological reflection, he came to focus on
“the practical usefulness of models” (Ashby 1970, 95) in helping us get on
with mundane, worldly projects.
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The great thing about a model, according
to Ashby, is that it enables us to
lose
information, and to arrive at something
more tractable, handle-able, manipulable, than the object itself in its infinite
complexity. As he put it, “No electronic model of a cat's brain can possibly
be as true as that provided by the brain of another cat, yet of what
use
is the
latter as a model?” (1970, 96). Models are thus our best hope of evading
Bremermann's limit in getting to grips with the awful diversity of the world
(1970, 98-100).
For Ashby, then, knowledge was to be thought of as engaged in practical
projects and worldly performances, and one late essay, written with his stu-
dent Roger Conant, can serve to bring this home. “Every Good Regulator of a
System Must Be a Model of That System” (Conant and Ashby 1970) concerned
the optimal method of feedback control. The authors discussed two different
feedback arrangements: error- and cause-controlled. The former is typified by
a household thermostat and is intrinsically imperfect. The thermostat has to
wait until the environment drives the living-room temperature away from its
desired setting before it can go to work to correct the deviation. Error control
thus never quite gets it right: some errors always remain—deviations from
the optimum—even though they might be much reduced by the feedback
mechanism. A cause-controlled regulator, in contrast, does not need to wait
for something to go wrong before it acts. A cause-controlled thermostat, for
example, would monitor the conditions outside a building, predict what those
conditions would do to the interior temperature, and take steps in advance to
counter that—turning down the heating as soon as the sun came out or what-
ever. Unlike error control, cause control might approach perfection: all traces
of environmental fluctuations might be blocked from affecting the controlled
