ZOOLOGY, AND THE PHILOSOPHY OF EVOLUTION 131 



plete, from beginning to end, we should expect to find that our 

 confidence in its stability had been reasonable, and judicious, and 

 wise throughout, and that any other expectation would have been 

 folly and suicide, bodily as well as mental; and that it is only in 

 this sense that we could assert that it all lay potentially in the 

 cosmic vapor. 



It is not because I dread or fear the philosophy of evolution, 

 that I refuse to accept it ; but because it is not yet proved. When 

 it is proved I shall accept it with cheerfulness ; for I most as- 

 suredly hold no belief which is inconsistent with it ; although I 

 fail to see how the reduction of all nature to mechanical princi- 

 ples could show that nature is determinate ; for if exhaustive 

 knowledge of "primitive nebulosity" should sometime show that 

 there is nothing in nature which might not have been expected, 

 I cannot see how this could show why the things we expect 

 should be the things which come about. 



They who assert that complete knowledge would be fore- 

 knowledge, forget that, for minds like ours, the only source of 

 knowledge, either complete or incomplete, is evidence ; for evi- 

 dence can tell us only what has happened, and it can never as- 

 sure us that the future must be like the past. Even if we knew 

 all that has happened, from the beginning down to the present 

 moment, we should have to regard the unknown remainder as 

 equal, in all probability, to the known past. To my mind, Jevons's 

 demonstration that, if certainty be represented by unity, the utmost 

 confidence we can ever reach by complete knowledge can never 

 exceed a value of one-half, seems conclusive; but even if it be 

 increased until it differ from certainty by less than any assignable 

 quantity, it must still remain nothing but reasonable confidence. 



There may be some unknown reason why the stone which I 

 set free from my hand must fall, and it may be that, as my mind 

 has been shaped by natural selection, I am unable to expect any- 

 thing else than that it shall fall; but science affords no evidence 

 that its fall is necessary or predetermined; for most thoughtful 

 students assure us that the inductive study of nature tells us 

 nothing about it, except that, so far as we know, all stones, so 

 placed, have fallen according to Newton's laws, and that we have 

 not the smallest reason to expect that any stone, so placed, will 



