CHANCE, AND ITS ELIMINATION. 61 



be connected with some particular wind through 

 causation ; that is, although they cannot be always 

 effects of the same cause (for if so they would always 

 coexist), there may be some causes common to the 

 two, so that in so far as either is produced by those 

 common causes, they will, from the laws of the causes, 

 be found to coexist. How, then, shall we ascertain 

 this ? The obvious answer is, by observing whether 

 rain occurs with one wind more frequently than with 

 any other. That, however, is not enough ; for per- 

 haps that one wind blows more frequently than any 

 other ; so that its blowing more frequently in rainy 

 weather is no more than would happen, although it 

 had no connexion with the causes of rain, provided it 

 were not connected with causes adverse to rain. In 

 England, westerly winds blow during about twice as 

 great a portion of the year as easterly. If, therefore, 

 it rains only twice as often with a westerly, as with an 

 easterly wind, we have no reason to infer that any law 

 of nature is concerned in the coincidence. If it rains 

 more than twice as often, we may be sure that some 

 law is concerned; either there is some cause in 

 nature tending to produce both rain and a westerly 

 wind, or a westerly wind has itself some tendency to 

 produce rain. But if it rains less than twice as often, 

 we may draw a directly opposite inference ; the one, 

 instead of being a cause, or connected with causes of 

 the other, must be connected with causes adverse to 

 it, or with the absence of some cause which produces 

 it ; and although it may still rain much oftener with 

 a westerly wind than with an easterly, so far would 

 this be from proving any connexion between the phe- 

 nomena, that the connexion proved would be between 

 rain and an easterly wind, the wind to which, in mere 

 frequency of coincidence, it is least allied. 



