Ill CRITICISMS OX " THE ORIGIN OF SPECIES " 83 



or organism (A) is precisely fitted to perform a 

 function or purpose (B) ; therefore it was specially 

 constructed to perform that function. In Paley's 

 famous illustration, the adaptation of all the parts 

 of the watch to the function, or purpose, of showing 

 the time, is held to be evidence that the watch 

 was specially contrived to that end ; on the ground, 

 that the only cause we know of, competent to 

 produce such an effect as a watch which shall keep 

 time, is a contriving intelligence adapting the 

 means directly to that end. 



Suppose, however, that any one had been able 

 to show that the watch had not been made directly 

 by any person, but that it was the result of the 

 modification of another watch which kept time but 

 poorly ; and that this again had proceeded from a 

 structure which could hardly be called a watch 

 at all seeing that it had no figures on the dial 

 and the hands were rudimentary ; and that going 

 back and back in time we came at last to a re- 

 volving barrel as the earliest traceable rudiment 

 of the whole fabric. And imagine that it had 

 been possible to show that all these changes 

 had resulted, first, from a tendency of the structure 

 to vary indefinitely ; and secondly, from something 

 in the surrounding world which helped all variations 

 in the direction of an accurate time-keeper, and 

 checked all those in other directions ; then it is 

 obvious that the force of Paley's argument would 

 be gone. For it would be demonstrated that an 



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