An Introduction to a Biology 



mind is suddenly confronted with an apparition, a 

 theory, which fits a phenomenon so closely, down to 

 the smallest crevice, that the theory showed none 

 of the features of the human mind at all but only a 

 cast of those of the phenomenon, the apparition 

 would mean nothing to the mind at all (unless the 

 phenomenon to be explained was a product of the 

 human mind). <But if the mind were confronted with 

 an apparition which was sufficiently like a mind to 

 show that it was the offspring of a mind, but also 

 showed, by the indentations on it, what phenomenon 

 that mind had been pressing its face against, then 

 the mind would be confronted with an apparition, a 

 theory (as, for instance, Natural Selection, a theory 

 involving such essentially human ideas as utility and 

 competition) which it could at once understand. 

 In other words, a perfectly fitting theory would be 

 utterly unintelligible to the mind. A condition of 

 the intelligibility of a theory, it seems to me, is that 

 it must not contain too much of the phenomenon 

 (unless that phenomenon happens to be a product 

 of the human mind) or it will be unintelligible. It 

 must, of course, be, or have been, in contact with 

 the phenomenon at one or two points, just to show 

 which phenomenon it is supposed to be explaining. 

 We have, therefore, an argument for the view that the 

 acceptability of a theory is evidence not of the accu- 

 racy with which that theory fits the phenomenon, but 

 of its remoteness from it. In other words, an accept- 

 able theory is more likely to be one which resembles 

 the mind, than one which resembles the phenomenon 

 (provided that that phenomenon is not also a product 

 of a mind, such as a murder or a machine). 



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