7/6 AN INTRODUCTION TO CYBERNETICS 



he intuitively attempts to stop the communication by enforcing a 

 reduction of the possibiHties to one — always sweetened, never a 

 spoon, coffee only, and so on. As soon as the possibilities shrink 

 to one, so soon is communication blocked, and the beverage robbed 

 of its power of transmitting information. The transmission (and 

 storage) of information is thus essentially related to the existence of a 

 set of possibilities. The example may make this statement plausible ; 

 in fact it is also supported by all the work in the modern theory of 

 communication, which has shown abundantly how essential, and 

 how fruitful, is the concept of the set of possibilities. 



Communication thus necessarily demands a set of messages. Not 

 only is this so, but the information carried by a particular message 

 depends on the set it comes from. The information conveyed is not 

 an intrinsic property of the individual message. That this is so can 

 be seen by considering the following example. Two soldiers are 

 taken prisoner by two enemy countries A and B, one by each; and 

 their two wives later each receive the brief message "I am well". It 

 is known, however, that country A allows the prisoner a choice from 



I am well, 



I am slightly ill, 



I am seriously ill, 



while country B allows only the message 



/ am well 



meaning 'T am alive'\ (Also in the set is the possibility of " no 

 message".) The two wives will certainly be aware that though 

 each has received the same phrase, the informations that they have 

 received are by no means identical. 



From these considerations it follows that, in this book, we must 

 give up thinking, as we do as individuals, about "this message". 

 We must become scientists, detach ourselves, and think about 

 "people receiving messages". And this means that we must turn 

 our attention from any individual message to the set of all the 

 possibilities. 



VARIETY 



7/6. Throughout this Part we shall be much concerned with the 

 question, given a set, of how many distinguishable elements it 

 contains. Thus, if the order of occurrence is ignored, the set 



'c, b, c, a, c, c, a, b, c, b, b, a 

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