NATURE OP STATISTICAL KNOWLEDGE 87 



of the combined action of a great number of 

 causes, each of which alone produced but a small 

 part of the final total effect. There is clearly so 

 much truth in this point of view as is included in 

 the fact that individual events or phenomena do, 

 in some degree or other, vary, and further these 

 variations in general distribute themselves more^ 

 or less in accord with the well-known laws of errors.' 

 But the assertion that events are individually 

 the outcome of the action of great numbers of 

 causes, each of which had a small part and a 

 part significantly equal to that played by every 

 other one of the causes concerned in the final 

 result, is only true if the "universe of discourse" 

 is indefinitely extended in time. But practically 

 science works in a definitely and rather narrowly 

 limited universe of discourse so far as concerns 

 time. One of the causes for the writing of these 

 lines is that a certain worthy was not shipwrecked 

 in voyaging to this country nearly 300 years ago, 

 since if he had been shipwrecked presumably I 

 should not exist and therefore could not write 

 these words. But practically this cause had very 

 little to do with determining that I, being here in 

 existence, should write this book rather than do 

 various other things which I might have done 

 instead. It undoubtedly is true that a vast 

 number of small causes do play a part in the 

 determination of any particular event. But, in 

 many of the events, at least, in which science is 



