40 Information Storage and Neural Control 



experience is by definition private. The Principle is seen to be an 

 elastic phrase which can be distorted to fit whatever data are 

 presented. Zipf has committed an error whicli psychologists have 

 been attempting to eliminate for fifty years. This is why I have 

 used the term "mentalistic" to describe Zipfs theory. 



But let us take one quick look at how the principle is applied 

 to the word-frequency results. Zipf argues on teleological grounds. 

 From the viewpoint of the speaker's purpose, communication 

 would require least effort if one word could be used to convey 

 every meaning, for then no decision would be necessary. From 

 the auditor's viewpoint, every meaning should have a separate 

 code, for then his effort would be least. Thus, we have the Foice of 

 Unification in opposition to the Force of Diversification, tending to 

 create a vocabulary balance. I wish to quote the following passage 

 from Zipfs book as an example of the application of the Principle: 



"We obviously do not yet know that there is in fact such a 

 thing as vocabulary balance between our hypothetical Forces of 

 Unification and Diversification, since we do not yet know that 

 man invariably economizes with the expenditure of his effort; for 

 that, after all, is what we are trying to prove. Nevertheless — and 

 we shall enumerate for the sake of clarity — if 1) we assume ex- 

 plicitly that man does invariably economize with his effort, and 

 if 2) the logic of our preceding analysis of a vocabulary balance 

 between the two Forces is sound, then 3) we can test the validity 

 of our explicit assumption of an economy of effort by appealing 

 directly to the objective facts of samples of actual speech that 

 have served satisfactorily in communication. Insofar as 4) we may 

 find therein evidence of a vocabulary balance of some sort in 

 respect of our two Forces, then 5) we shall find ipso facto a con- 

 firmation of our assumption of 1) an economy of effort." (9). 



The argument which has been presented is scientifically sound: 

 deduce something from theoretical assumptions; if the deduction 

 is empirically verified, the theory has found support. Our only 

 quarrel is with the weakness of the prediction. All that has been 

 predicted is that passages of actual speech or writing will not be 

 repetitions of the same single word, nor will all words be different. 

 The absence of detailed specification of the constructs of the theory 

 leads only to predictions which are trivial, and yet the superficial 



