CHANCE, AND ITS ELIMINATION. 55 



regard to the presence or absence of A, will exist in one 

 case out of those three. There will therefore be, of the 

 whole number of cases, two in which A exists without B ; 

 one case of B without A ; two in which neither B nor A 

 exists, and one case out of six in which they both exist. 

 If then, in point of fact, they are found to coexist oftener 

 than in one case out of six ; and, consequently, A does not 

 exist without B so often as twice in three times, nor B with- 

 out A so often as once in every twice ; there is some cause 

 in existence which tends to produce a conjunction between A 

 and B. 



Generalizing the result, we may say, that if A occurs in 

 a larger proportion of the cases where B is, than of the cases 

 where B is not ; then will B also occur in a larger proportion 

 of the cases where A is, than of the cases where A is not ; and 

 there is some connexion, through causation, between A and B. 

 If we could ascend to the causes of the two phenomena, we 

 should find, at some stage, either proximate or remote, some 

 cause or causes common to both ; and if we could ascertain 

 what these are, we could frame a generalization which would 

 be true without restriction of place or time : but until we can 

 do so, the fact of a connexion between the two phenomena 

 remains an empirical law. 



3. Having considered in what manner it may be deter- 

 mined whether any given conjunction of phenomena is casual, 

 or the result of some law ; to complete the theory of chance, 

 it is necessary that we should now consider those effects which 

 are partly the result of chance and partly of law, or, in other 

 words, in which the effects of casual conjunctions of causes 

 are habitually blended in one result with the effects of a 

 constant cause. 



This is a case of Composition of Causes ; and the pecu- 

 liarity of it is, that instead of two or more causes intermixing 

 their effects in a regular manner with those of one another, 

 we have now one constant cause, producing an effect which 

 is successively modified by a series of variable causes. Thus, 

 as summer advances, the approach of the sun to a vertical 



