About “regulation”, and turn simply to certain questions related to
The design and construction of a machine, any machine.
251
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
RE GU LA TI N G TH E V ER Y LA R GE SY STE M
Our treatment of it, while losing nothing in precision, must be
Very broad— that is to say, abstract— for, as biologists, we want to
Consider machines of far wider type than those of steel and brass.
Within the formula
Entity Ω designs machine M
We want to include such cases as
L) The genes determining the formation of the heart.
A mechanic making a bicycle.
One part of the brain determining the internal connexions in
A nerve-net.
A works-manager laying out a factory to get production go-
Ing along certain lines.
A mathematician programming an automatic computer to
Behave in a certain way.
What we shall be concerned with, if we hold to the cybernetic
Point of view, is not the more obvious processes of shaping or
Assembling pieces of matter, but with the less obvious questions of
What determines the final model, of how it comes to be selected.
We are interested in tracing long chains of cause and effect, so that
We can relate a set of possible initial causes to a set of final
Machines issuing as consequence; as a telephone mechanic, with a
Cable of a hundred wires, relates each one going in at one end to
Some one coming out at the other. By treating the matter in this
Way we shall find that certain quantitative relations must hold; on
Them we can base the ideas of the last chapter. Throughout, we
Shall be exemplifying the thesis of D. M. MacKay: that quantity of
Information, as measured here, always corresponds to some quan-
Tity, i.e. intensity, of selection, either actual or imaginable.
The concepts of selecting, designing, constructing, building
(briefly, in any way being responsible for the eventual appearance
Of) an actual machine share a common property, when one identi-
Fies and measures the varieties concerned in the process. What
Might turn up as M has variety— an embryo might produce any one
Of many forms of muscular blood-pump. In fact, the gene-pattern in
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Lumbricus leads to the production of an earthworm’s heart, the
Gene-pattern in Rana leads to the production of a frog’s heart, and
That in Homo to a man’s heart. Control, by the gene-pattern over the
Heart, is clearly involved. So too is regulation, for in whatever state
The molecules in Lumbricus happen to be initially (there being vari-
Ety in the possibilities), under the action of the gene-pattern the
Variety disappears, and a heart of standard worm’s form appears.
252
It will be noticed that the concepts of design or construction are
Essentially applicable to sets, in spite of the common linguistic use
Of the singular. (Compare S.7/3.) Thus “the gene-pattern deter-
Mines the form of the heart” is a shorthand way of saying that ele-
Ments in the set of gene-patterns among different species can be
Put into correspondence with those in the set of possible hearts in
The various species, like the wires at the two ends of a telephone
Cable. Thus the act of “designing” or “making” a machine is
Essentially an act of communication from Maker to Made, and the
Principles of communication theory apply to it. In particular the
Measures that were developed for treating the case in which vari-
Ous possible messages are reduced to one message can now be
Applied to the case when various possible machines are reduced to
One machine.
A useful conceptual device for forcing this aspect into promi-
Nence is to imagine that the act of designing has to take place
Through the telephone, or by some other specific channel. The
Quantities of variety can then readily be identified by identifica-
Tion of the actual quantity of information that will have to be trans-
Mitted.
When a designer selects the final form of the machine,
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What does “selecting” the machine mean in terms of the general
Concepts of this book? Consider the following sequence of exam-
Ples, in which the final machine is a radio receiver.
The first is the case of the buyer who has three machines before
Him, and he selects one. The second case, equivalent to the first
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