192 THE SCIENCE OF LOGIC 



expenditure of natural resources, with which these metals can be obtained, and 

 will therefore diminish (i.e. money prices will rise) according as mines become 

 numerous and fertile &quot;. 



In the sciences of observation, especially in the social, politi 

 cal, and economic sciences, the immediate data to which the present 

 method is most fruitfully applied are not merely isolated facts as 

 they come, more or less haphazard, under our notice. What is 

 true of all the methods (240) is true of the present one : the raw 

 materials of ordinary experience have to be prepared for its ap 

 plication. And here the preparation will consist in the careful 

 compilation of statistics. 



We are said to compile statistics when we count or compute 

 the number of instances of the occurrence of a phenomenon and 

 if possible, also, the measure or degree in which it occurs in each 

 instance within any selected limits of time and space. Thus, if 

 we measure the rainfall of each of the counties of Ireland for each 

 month, or for each season, during a period of, say, five years, we 

 are preparing, arranging, tabulating, the results of our observations 

 in such a way as to enable us to suspect causal connexions, 

 which might otherwise have remained undetected, between rain 

 fall and other phenomena such as the succession of the seasons, 

 the distribution of land and water in the country, the prevalent 

 direction of the winds, the proximity of the ocean, the existence 

 of mountain ranges, etc. It is mainly by bringing to light the 

 existence of concomitant variations between phenomena, that 

 statistics thus suggest causal connexions, or help us to test con 

 nexions whose existence may have been already suspected. 

 Observations tabulated in this way enable us to compare the relative 

 frequency with which different phenomena occur, and often to 

 measure the relative amounts of these phenomena, within a given 

 range of time or space. Uniform concomitant variations, brought 

 to light in this way, suggest the existence of some law of causal 

 connexion between the phenomena so varying and may even 

 convince us that the variations are not mere casual coincidences : 

 may, in other words, prove the existence of some causal law without 

 at the same time enabling us to determine what is the total 

 cause of the variation, or what are the partial causes, or any of 

 them, in virtue of which the observed phenomena occur and vary 

 concomitantly as they do. 



Suppose, for instance, that intemperance among the poorer 

 classes in a city is observed to vary concomitantly with the squalor 



