CHAPTER XI 



Mendel's explanation op his results 



In this chapter we pass from the description of facts 

 as to which men with unimpaired sense of sight 

 are all agreed, to the consideration of hypotheses 

 about which men whose judgment estimated by the 

 usual standards is sound are widely at variance. 

 At this point, therefore, we bid farewell to the broad 

 daylight of observation, and enter the dark and 

 treacherous alleys of inference. Before we take 

 this step, it is well to reflect on the nature of the 

 errand on which we are engaged. 



A theory commonly held as to the nature of the 

 explanation of a sequence of events is that explana- 

 tion consists in the discovery of the principles under- 

 lying and determining this sequence. The essence 

 of this theory is that explanation consists in seeing 

 below what is observed, and finding out how it is 

 worked ; and this probing downwards is regarded 

 as one step of a grand downward journey of explora- 

 tion, the goal of which is the discovery of the causes 

 of all phenomena. Those who hold this theory of 

 the nature of explanation believe that each downward 

 step is one stage nearer to the truth below — a day's 

 march nearer home. 



Now, if this view of the matter were the true 



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