Or whether it should be scrapped. Sometimes the problem arose
Practically, as when a telephone engineer considered a compli-
Cated set of relations between tests applied and results observed,
In the middle of a mass of functioning machinery that was not to
Be dismantled for insufficient reason.
Though the problem arose in purely electrical form, its range of
Application is far wider. The clinician studying a patient with
Brain damage and aphasia may be trying, by means of tests given
And speech observed, to deduce something of the mechanisms that
Are involved. And the psychologist who is studying a rat in a maze
May act on the rat with various stimuli and may observe the rat’s
Various behaviours; and by putting the facts together he may try
To deduce something about the neuronic mechanism that he can-
Not observe. I need not give further examples as they are to be
Found everywhere (S.6/17).
Black Box theory is, however, even wider in application than
These professional studies. The child who tries to open a door has
To manipulate the handle (the input) so as to produce the desired
Movement at the latch (the output); and he has to learn how to
Control the one by the other without being able to see the internal
Mechanism that links them. In our daily lives we are confronted at
Every turn with systems whose internal mechanisms are not fully
Open to inspection, and which must be treated by the methods
Appropriate to the Black Box.
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The experimenter who is not interested in Black Box theory
Usually regards any casing as merely a nuisance, for it delays his
Answering the question “what is in this Box?” We, however, shall
Be considering such larger questions as
How should an experimenter proceed when faced with a Black
Box ?”
What properties of the Box’s contents are discoverable and
What are fundamentally not discoverable ?”
What methods should be used if the Box is to be investigated
Efficiently ?”
Proper attention can be given to these questions only by our
Accepting the existence, at least temporarily, of a casing, and pro-
Ceeding accordingly. Then, and only then, can we develop a sci-
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Entific epistemology.
To start with, let us make no assumptions at all about the
Nature of the Box and its contents, which might be something, say,
That has just fallen from a Flying Saucer. We assume, though, that
The experimenter has certain given resources for acting on it (e.g.
Prodding it, shining a light on it) and certain given resources for
Observing its behaviour (e.g. photographing it, recording its
Temperature). By thus acting on the Box, and by allowing the Box
To affect him and his recording apparatus, the experimenter is cou-
Pling himself to the Box, so that the two together form a system
With feedback:
Box ← Experimenter →
For the coupling to be made in some defined and reproducible
Way, the Box’s “input” must be specified, if only arbitrarily and
Provisionally. Every real system has an indefinitely large number
Of possible inputs— of possible means by which the experimenter
May exert some action on the Box. Equally, it has an indefinitely
Large number of possible outputs— of ways by which it may affect
The experimenter, perhaps through recording instruments. If the
Investigation is to be orderly, the set of inputs to be used and of
Outputs to be observed must be decided on, at least provisionally.
Let us assume, then, that this has been done.
The situation that we (author and reader) are considering can be
Made clearer by the introduction of two harmless conventions. Let
It be assumed that the inputs, whatever their real nature, are
Replaced by, or represented by, a set of levers or pointers— like the
Controls to a domestic cooking oven. We can then be quite clear
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A N I N T R O D UC T I O N T O C Y B E R NE T I C S
TH E BL AC K B O X
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