Act of shuffling— which has selected the distribution of the cards.
(Compare Fig. 12/22/1.) The Rules of Bridge ensure, in fact, that a
Definite part of the whole determination shall be assigned to chance,
I.e. to shuffling carried out in a prescribed way. Such an appeal to
Chance was frequently used in the past as a method for supplement-
Ing selection. The Roman general, for instance, after having made
Many decisions, would often leave the remainder to be determined
By some other factor such as the flight of the next flock of birds, or
The configurations shown in the entrails of a freshly-killed sheep.
(Supplementation was used earlier in this book in S.4/19 and 12/15.)
In scientific work the first deliberate use of wholly uncorrelated
Selectors to provide “random” determination to complete the
Selection imposed by the experimenter, was made apparently by
Sir Ronald Fisher; for he first appreciated its fundamental impor-
Tance and usefulness.
By saying a factor is random, I do not refer to what the factor
Is in itself, but to the relation it has with the main system. Thus the
successive digits of π are as determinate as any numbers can be,
Yet a block of a thousand of them might serve quite well as ran-
Dom numbers for agricultural experiments, not because they are
Random but because they are probably uncorrelated with the
Peculiarities of a particular set of plots. Supplementation by
“chance” thus means (apart from minor, special requirements)
Supplementation by taking effects (or variety) from a system
Whose behaviour is uncorrelated with that of the main system. An
Example was given in S.12/15. Thus if a chance variable were
Required, yesterday’s price of a gold-share might be suitable if the
Main system under study was a rat in a maze, but it would not be
Suitable if the main system were a portion of the financial-eco-
Nomic system.)
S ELE CT I ON AND M ACHI NER Y
Selection by machine. In the preceding sections we have
Considered the questions of communication involved when a
Machine is to be selected. Whatever does the selecting is, how-
Ever, on general cybernetic principles, also to be considered as a
Mechanism. Thus, having considered the system
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L → M
When L acts so as to design or select the machine M, we must now
Consider L as a machine, in some way acting as designer or selec-
259
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
Tor. How can a machine select? The answer must, of course, be
Given in terms compatible with those already used in this Part.
Perhaps the simplest process of selection occurs when a machine
Goes along a particular trajectory, so that after state i (say) it goes to
State j (say) and not to any other of its states. This is the ordinary
Selection that a machine makes when its “message” (the protocol
From it) says that the machine has this transformation and no other.
Another process of selection shown by a machine is that noticed
In S.7/24: every determinate machine shows selection as it
Reduces the variety in its possible states from the maximum ini-
Tially to the number of its basins finally.
Another process of selection was treated in S.5/13, when one part
Of a whole can select from states of equilibrium in the other part by
“vetoing” some of them. This is perhaps the most obvious form of
Selection, for, as the two are watched, the imaginative observer can
almost hear the vetoing part say “… no good, still no good, I won’t
have it, still no good, Hold It!— yes, we’ll keep that permanently.”
If a machine is to be built as a selector (perhaps to carry out the pro-
Gramme hinted at in the final section) it will, so far as I can see, have
To be built to act in this way. It is the way of the second-order feed-
Back in Fig. 5/14/1 (supplemented in S.12/15).
There are doubtless other methods, but these will suffice for
Illustration, and they are sufficient to give definiteness to the idea
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Of a machine “selecting”; (though special consideration is hardly
Necessary, for in Shannon’s theory every act of communication is
Also one of selection— that by which the particular message is
Caused to appear).
Duration of selection. At this point a word should be said
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