LECTURE XII 



THE MECHANISM OF NATURE 



In this lecture I shall review the evidence that has convinced 

 many thoughtful men that natural knowledge is no more than 

 knowledge of order. My reason for asking you to go with me 

 over ground which is already familiar is this : I wish you to ask 

 yourselves, as we make our review, if it is not obvious that the 

 discovery that nature is orderly can throw no light on the origin 

 of anything in nature. Order is not an explanation of anything ; 

 but something that itself calls for explanation. 



It must not be supposed that no "philosopher" has attempted 

 to account for order in nature; for many hold this a simple mat- 

 ter, easy to understand, although their reasoning may turn out, 

 when examined, to be no more than an assertion that nature is 

 orderly because there is order in nature. 



Some tell us, for example, that the order we discover in nature 

 is a necessary result of the conservation of energy. Like causes 

 must be followed by like effects, they tell us, unless force has 

 in the meantime come into existence or gone out of existence; 

 and this cannot be the case if force is persistent. As proof that 

 force is persistent we are told that like effects do follow like 

 causes, or, in other words, that nature is orderly. 



Some students of zoology go one step deeper into the heart 

 of the matter, and tell us that our minds are unable to conceive 

 the production or the destruction of energy, because the whole 

 history of life has been a history of response to causation, and 

 because all living things that did not thus respond have been 

 exterminated in the struggle for existence, and because, for this 

 reason, our confidence in the order of nature is no more than 

 our history would lead one to expect; although it seems plain 



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