THE INHERITANCE OF MENTAL TRAITS 433 



cannot, I think, be controverted. 1 As far as I am able to judge, I 

 have drawn no illegitimate inferences. Pearson's reasoning, in the 

 very cases which he instances, appears to me demonstrably wrong. 

 His main inference is that, since offspring resemble one another in 

 the same degree in, for example, probity and eye-colour, therefore 

 these characters are both ' innate.' But, if his reasoning is valid 

 as regards the mental and physical characters named by him, it 

 should be valid also as regards other characters not named. Now 

 English school children resemble one another absolutely in that 

 they all possess heads, lungs, livers, and so forth. Here the degree of 

 resemblance is ' unity.' They reproduce these characters with much 

 greater certainty than eye and hair-colour and variations in fore- 

 arm and span. They also resemble one another absolutely in that, 

 when they have reached a certain age, they can all read, write, and 

 speak the English language, and in that they have English notions 

 of modesty with respect to clothes. Here, again, the degree of 

 resemblance is roughly ' unity.' At any rate they reproduce these 

 characters with much greater certainty than they do eye-colour and 

 the like. Moreover, in the case of the boys, there is a mental tendency, 

 almost as universal as their sex, to wear trousers ; in the case of 

 the girls, to wear frocks. The children would be infinitely reluctant 

 to appear at school without these garments. Must we suppose, 

 then, that this sameness involves a like heritage, a similarity of the 

 germ-plasm, and that English children ' inherit ' these characters, 

 which are universally regarded as acquirements and would probably 

 be admitted as such by Pearson, with a degree of certainty which 

 is almost as great as that with which they inherit heads, livers, and 

 sexual organs ? I do not mean in the least to be offensive in the 

 examples I have drawn. I have selected them merely in order to 

 indicate as strongly and vividly as possible the reasons that have 

 led me to think that Pearson's thinking, founded as it is solely on 

 biometric data, though much more massive and conclusive evidence 

 is available, and quite untested as it is by any appeal to reality, is 

 totally mistaken and illegitimate. Biometry is capable of demon- 

 strating the degrees in which given characters tend on the average to 

 be reproduced by offspring under given conditions. But, if we wish 

 to ascertain the category to which any of these characters belongs 

 whether it is * inborn ' or * acquired ' we must draw an inference 

 which biometry, a mode of observing not of thinking, cannot help 

 us to draw ; and which, therefore, must be tested as carefully as 

 when our facts have been otherwise gathered. 



1 See also chapter xxv. 

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