4/21 AN INTRODUCTION TO CYBERNETICS 



variable, and at the other end the totally-unjoined form, in which 

 every variable is independent of every other. Systems can thus 

 show more or less of "wholeness". Thus the degree may be specifi- 

 able statistically even though the system is far too large for the details 

 to be specified individually. 



Ex.: Can a disturbance at A (Fig. AjlOIV) affect B in the left-hand system? In 

 the other two? 



4/21. Local properties. Large systems with much repetition in the 

 parts, few immediate effects, and slight couplings, can commonly 

 show some property in a localised form, so that it occurs in only a 

 few variables, and so that its occurrence (or not) in the few variables 

 does not determine whether or not the same property can occur in 

 other sets of a few variables. Such localisable properties are usually 

 of great importance in such systems, and the remainder of this 

 chapter will be given to their consideration. Here are some 

 examples. 



In simple chemistry — the reaction of silver nitrate in solution with 

 sodium chloride for instance — the component parts number about 

 1022, ti^us constituting a very large system. The parts (atoms, ions, 

 etc.) are largely repetitive, for they consist of only a dozen or so 

 types. In addition, each part has an immediate effect on only a 

 minute fraction of the totaUty of parts. So the coupling (or not) 

 of one silver ion to a chloride ion has no effect on the great majority 

 of other pairs of ions. As a result, the property "coupled to form 

 AgCl" can exist over and over again in recognisable form throughout 

 the system. Contrast this possibility of repetition with what happens 

 in a well coupled system, in a thermostat for instance. In the 

 thermostat, such a localised property can hardly exist, and can 

 certainly not be repeated independently elsewhere in the system ; for 

 the existence of any property at one point is decisive in determining 

 what shall happen at the other points. 



The change from the chemistry of the solution in a test tube to 

 that of protoplasm is probably of the same type, the protoplasm, as 

 a chemically dynamic system, being too richly interconnected in its 

 parts to allow much local independence in the occurrence of some 

 property. 



Another example is given by the biological world itself, regarded 

 as a system of many parts. This system, composed ultimately of 

 the atoms of the earth's surface, is made of parts that are largely 

 repetitive, both at a low level in that all carbon atoms are chemically 

 alike, and at a high level in that all members of a species are more or 



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