NATURE OF STATISTICAL KNOWLEDGE 93 



question in statistical probability the appropriate 

 way, of course, to go about solving it is to turn up 

 the registration reports for the city of Baltimore 

 covering a period of years, and find out what is the 

 proportion of white to colored births in that city. 

 Then, by the simplest theorem in the calculus of 

 chance, the probability that the next birth will be 

 of a white child will be given by a fraction of 

 which the numerator is the number of white 

 children born in Baltimore and the denominator 

 is the total number of children born in Baltimore, 

 both figures including the same period of time. 

 The difference between the fraction so obtained 

 and 1 will be the probability that the next birth 

 will be of a child not white ; that is, colored. When 

 we have obtained such a fraction we have a definite 

 piece of statistical knowledge, but of just what use 

 is it so far as concerns the individual case? It 

 implies no biological knowledge of any kind ; 

 no knowledge of the laws of heredity. It really 

 adds essentially, it seems to me, to the sum total 

 of the world's knowledge only one thing. That 

 thing is the proper betting odds on what the 

 color of the next child born in the city will be. 

 This knowledge would really be useful, in a 

 pragmatic sense, only provided some one wishes 

 to gamble upon that event. 



Of course the statistical count, on which the 

 probability is based, in itself furnishes definite 

 and precise information about the population of 



